LABORATORY MANUAL

FOR
NETWORKING LAB
4TH Semester
Diploma in Computer Science & Engineering

C. V. Raman Polytechnic
Bidya Nagar, Mahura, Janla, Bhubaneswar
S/N LIST OF PRACTICALS PAGE
NO NO
1 Recognize the physical topology and cabling (coaxial, OFC, 1-7

UTP, STP) of a Network

2 Recognition and use of various types of connectors RJ-45, 8-11

RJ-11, BNC and SCST.

3 Making of cross cable and straight cable. 12-14

4 Install and configure a network interface card in 15-17

workstation.

5 Identify the IP address of a workstation and the class of the 18-24

address and configure the IP Address on a workstation.

6 Managing user accounts in windows and LINUX 25-26

7 Sharing of Hardware resources in the network. 27-28
8 Use of Netstat and its options 29
9 Connectivity troubleshooting using PING, IPCONFIG 30
10 Installation of Network Operating System (NOS). 31-33
11 Create a network of at least 6 computers 34-35
12 Study of Layers of Network and Configuring 36-42

Network Operating System

13 Study of Routing and Switching, configuring of Switch 43-53

and Routers, Troubleshooting of Networks.

14 Study of Scaling of Networks, 54-56

Design verities of LAN and forward of traffic

15 Study WAN concepts and Configure and forward 57-58

Traffic in WAN
16 Configure IPv4 and IPv6 and learn Quality, 59-74

security and other services

17 Learn Network programming 75-78

18 Troubles shoot Networks 79-152
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 Practical 11
Aim: Create a network of at least 6 computers

Requirements:

6 computers (laptops or desktops)

Ethernet cables or a switch/router with enough ports
Operating systems installed on each computer (e.g., Windows, Linux, macOS)

first of all In order to connect a computer to an Ethernet cable, the computer must have an
interface. In a desktop this is usually a Network Interface Card (NIC) or USB adapter.
In a laptop, it is usually a PC card, a module that plugs into the laptop. The Ethernet jack
may also be built into the laptop itself.

Procedure
1.Take the computer for which you are making server, insert the second LAN in that
computer.
2.Connect your internet connection into the first LAN (inbuilt) on that computer.
3.Enter the IP address which you got from your ISP and check whether you can able to use
internet on that system.

4.Now make sure that the second LAN is detected and is showing Unplugged.

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 5.Open properties of the first LAN (inbuilt LAN) and then go to "Advanced" option which is
available on the top, then check both the boxes and say ok. and close everything.
6.Now take an Internet cable which is crimped on both the sides with same colors of wires.
7.Connect one end to the second LAN and the other end to the switch.
8.Now open your second LAN properties and go to the TCP/IP properties and there enter IP
address as (192.168.0.1) or anything you wish 9.Subnet Mask (255.255.255.0) and the
gateway as (192.168.0.1).
10.Now open click on the switch and you will get a notification on your server saying that
"Local Area Connection 2" is connected.
11.Now take an another Internet cable and one end of that cable should be in any one port
of the Switch and the other should be in the second computer.
12.Now you will get a notification that you are connected to internet, open the LAN
properties and enter the IP address as (192.168.0.2) subnet mask and gateway should be
same as server. say ok
13.You will now be able to browse Internet on that particular system now.
14.Do the same with the rest of the systems.
And one more thing should be kept in mind that is you wont be able to browse internet
Unless or Until your Server Pc is turned ON.

Set up appropriate security measures such as firewalls, antivirus software, and user
authentication to protect the network from unauthorized access
.
Remember, this is a basic setup. For more complex networks or specific requirements
like connecting different types of devices or configuring advanced settings, you might
need more equipment or specific expertise.

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 Practical 12
AIM: Study of Layers of Network and Configuring Network Operating System

studying the layers of a network and configuring a Network Operating System (NOS)
involves understanding the OSI (Open Systems Interconnection) model and practically
configuring a NOS like Windows Server or Linux for networking purposes.

Understanding the OSI Model:

The OSI model consists of seven layers, each responsible for specific functions in network
communication:

Physical Layer: Deals with the physical connection between devices, including cables,
hubs, and switches.
Data Link Layer: Manages data frames, error detection, and MAC (Media Access Control)
addressing.
Network Layer: Focuses on logical addressing (IP addresses), routing, and packet
forwarding.
Transport Layer: Manages end-to-end communication, ensures data integrity, and controls
data flow.
Session Layer: Establishes, maintains, and synchronizes communication between devices.
Presentation Layer: Handles data translation, encryption, and decryption.
Application Layer: Provides network services to applications and end-users.

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 Configuring a Network Operating System (NOS):
Network Operating Systems:
UNIX, Linux, Microsoft Windows Server 2008, Microsoft Windows Server 2003, Novell
NetWare, Banyan's VINES, Artisoft's LANtastic, Mac OS X, and BSD

Let's consider configuring a Windows Server as a simple example.

Steps:

1.Installation: Install the Windows Server OS on a computer that will act as the server.
Follow the installation prompts, set passwords, and configure basic settings.

2.Setting IP Addresses: Access network settings to assign a static IP address to the server.
Use an address within the same subnet as other devices if you have an existing network.

3.Role Configuration: In Windows Server, roles and features determine what the server will
do. You can configure it as a domain controller, file server, DHCP server, DNS server, etc.
Use Server Manager to add roles and features based on your network requirements.

4.Configuration of Services:

 DHCP Configuration: If you're setting up a DHCP server, configure the scope (range
of IP addresses to assign), lease durations, and other settings for dynamic
addressing.
 DNS Configuration: Configure the DNS settings, create forward and reverse lookup
zones, add DNS records for your network devices.
 File Sharing: Set up shared folders and assign permissions to users/groups.
Firewall and Security Settings: Adjust the firewall settings to allow necessary network
traffic and ensure security measures are in place. Configure user accounts with
appropriate access permissions.

In other way A network operating system enables device hardware to function and provides
an interface for users to interact. In the CCNA course of study, students learn to configure
both devices that connect to the network (end devices such as PCs) and devices that connect
networks together (intermediary devices like routers and switches). Learning to configure the
Cisco Internetwork Operating System (Cisco IOS) on Cisco routers and switches is a large
part of the Cisco CCNA program of study.

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 1. Shell – the user interface that allows users to request specific tasks from
2. the computer.
3. These.requests can be made either through the CLI or GUI
interfaces
Kernel – communicates between the hardware and software of a computer and
manages how hardware resources are used to meet software requirements.
Hardware – the physical part of a computer including underlying electronics.

Access Methods
There are several ways to access the CLI environment and configure the device.
The most common methods are:

 Console – A physical port of a cisco device that provides access to the device via a
dedicated management channel, also known as out-of-band access
 SSH – A protocol to establish a remote secure CLI connection over the network.
 Telnet – An insecure method of remotely establishing a CLI session through a virtual
interface, over a network.

Primary Command Modes

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 As a security feature, the Cisco IOS software separates management access into the
following two command modes:

 User EXEC Mode – This mode has limited capa capabilities

bilities but is useful for basic
operations. It allows only a limited number of basic monitoring commands but does
not allow the execution of any commands that might change the configuration of the
device. The user EXEC mode is identified by the CLI prompt that ends with the >
symbol.
 Privileged EXEC Mode – To execute configuration commands, a network
administrator must access privileged EXEC mode. Higher configuration modes, like
global configuration mode, can only be reached from privileged EXEC mode. The
privileged EXEC mode can be identified by the prompt ending with the # symbol.
Configuration Command Modes

Two common sub-configuration

configuration modes include:

 Line Configuration Mode – Used to configure console, SSH, Telnet, or AUX access.
 Interface Configuration Mode – Used to configure a switch port or router network
interface.
Basic IOS Command Structure

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 Keyword– a specific parameter defined in the operating system (in the figure, ip
protocols)
 Argument – not predefined; a value or variable defined by the user (in the
figure, 192.168.10.5)
Device Names
Hostnames that appear in CLI pro
prompts
mpts can be used in various authentication
processes between devices, and should be used on topology diagrams. Identify network
devices, hostnames should:

 Start with a letter

 Contain no spaces
 End with a letter or digit
Use only letters, digits, and dashes
 Be less than 64 characters in length
Configure Hostnames

As shown in Figure, from the privileged EXEC mode, access the global configuration
mode by entering the configure terminal command. Notice the change in the
command prompt.

From global configuration mode, enter the command hostname followed by the
name of the switch and press Enter. Notice the change in the command prompt
name.

Note: To remove the configured hostname and return the switch to the default
prompt, use the no hostname global config command.
Secure Device Access
The use of weak or easily guessed passwords continues to be a security issue in
many facets of the business world. Network devices, including home wireless routers,
should always have passwords
swords configured to limit administrative access.

Cisco IOS can be configured to use hierarchical mode passwords to allow

different access privileges to a network device.

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Configure Passwords
The most important password to configure is access to the privileged EXEC
mode, as shown in Figure 1. To secure privileged EXEC access, use the enable
secret password global config command.

To secure the user EXEC access, the console port must be configured, as shown in
Figure 2. Enter line console configuration mode using the line console 0 global
configuration command. The zero is used to represent the first (and in most cases the
only) console interface. Next, specify the user EXEC mode password using
the password password command. Finally, enable user EXEC access using
the login command. Console access will now require a password before gaining
access to the user EXEC mode.

Virtual terminal (VTY) lines enable remote access to the device. To secure VTY lines
used for SSH and Telnet, enter line VTY mode using the line vty 0 15 global config
command, as shown in Figure 3. Many Cisco switches support up to 16 VTY lines
that are numbered 0 to 15. Next, specify the VTY password using
the password password command. Lastly, enable VTY access using
the login command.

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 Encrypt Password

The startup-config and running-config files display most passwords in plaintext. This
is a security threat since anyone can see the passwords used if they have access to
these files.

To encrypt passwords, use the service password-encryption global config

command. The command applies weak encryption to all unencrypted passwords. This
encryption applies only to passwords in the configuration file, not to passwords as they
are sent over the network.

Use the show running-config command to verify that passwords are now encrypted.

Banner Messages
To create a banner message of the day on a network device, use the banner motd
# the message of the day # global config command. The “#” in the command syntax is
called the delimiting character. It is entered before and after the message. The delimiting
character can be any character as long as it does not occur in the message. For this
reason, symbols such as the “#” are often used. After the command is executed, the
banner will be displayed on all subsequent attempts to access the device until the banner
is removed.

Save the Running Configuration File

There are two system files that store the device configuration:

 startup-config – The file stored in Non-volatile Random Access Memory (NVRAM) that
contains all of the commands that will be used by the device upon startup or reboot.
NVRAM does not lose its contents when the device is powered off.
running-config – The file stored in Random Access Memory (RAM) that reflects the
current configuration. Modifying a running configuration affects the operation of a Cisco
device. RAM is volatile memory. It loses all of its content when the device is powered off
or restarted.

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 Practical 13
AIM: Study of Routing and Switching, configuring of Switch and Routers,
Troubleshooting of Networks.

Network Switching
A switch is a dedicated piece of computer hardware that facilitates the process of
switching i.e., incoming data packets and transferring them to their destination. A
switch works at the Data Link layer of the OSI Model. A switch primarily hand the
incoming data packets from a source computer or network and decides the
appropriate port through which the data packets will reach their target computer or
network.

A switch decides the port through which a data packet shall pass with the help of its
destination MAC(Media Access Control) Address. A switch does this effectively by
maintaining a switching table, (also known as forwarding table).

Network Switch Works:

When the source wants to send the data packet to the destination, the packet first enters
the switch and the switch reads its header and finds the MAC address of the destination
to identify the device then it sends the packet out through the appropriate ports that lead
to the destination devices.

Switch establishes a temporary connection between the source and destination for
communication and terminates the connection once the conversation is done. Also, it
offers full bandwidth to network traffic going to and from a device simultaneously to
reduce collision.

A network switch is more efficient than a network Hub or repeater because it maintains a
switching table, which simplifies its task and reduces congestion on a network, which
effectively improves the performance of the network.

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Process of Switching
The switching process involves the following steps:

Frame Reception: The switch receives a data frame or packet from a computer
connected to its ports.

MAC Address Extraction: The switch reads the header of the data frame and collects
the destination MAC Address from it.
MAC Address Table Lookup: Once the switch has retrieved the MAC Address, it
performs a lookup in its Switching table to find a port that leads to the MAC Address
of the data frame.
Forwarding Decision and Switching Table Update: If the switch matches the
destination MAC Address of the frame to the MAC address in its switching table, it
forwards the data frame to the respective port. However, if the destination MAC
Address does not exist in its forwarding table, it follows the flooding process, in which
it sends the data frame to all its ports except the one it came from and records all the
MAC Addresses to which the frame was delivered. This way, the switch finds the new
MAC Address and updates its forwarding table.
Frame Transition: Once the destination port is found, the switch sends the data frame
to that port and forwards it to its target computer/network.

switching methods:

Message Switching
Circuit Switching
Packet Switching
Datagram Packet Switching
Virtual Circuit Packet Switching

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Message Switching: This is an older switchin
switchingg technique that has become obsolete.
In message switching technique, the entire data block/message is forwarded across
the entire network thus, making it highly inefficient.

Circuit Switching: In this type of switching, a connection is established between

betwee the
source and destination beforehand. This connection receives the complete bandwidth
of the network until the data is transferred completely.
This approach is better than message switching as it does not involve sending data to
the entire network, instead
ead of its destination only.

Packet Switching: This technique requires the data to be broken down into smaller
components, data frames, or packets. These data frames are then transferred to their
destinations according to the available resources in the ne
network
twork at a particular time.
This switching type is used in modern computers and even the Internet. Here, each
data frame contains additional information about the destination and other
information required for proper transfer through network components .
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Datagram Packet Switching: In Datagram Packet switching, each data frame is taken
as an individual entity and thus, they are processed separately. Here, no connection
is established before data transmi
transmission
ssion occurs. Although this approach provides
flexibility in data transfer, it may cause a loss of data frames or late delivery of the
data frames.

Virtual-Circuit
Circuit Packet Switching: In Virtual
Virtual-Circuit
Circuit Packet switching, a logical
connection between the sou
source
rce and destination is made before transmitting any data.
These logical connections are called virtual circuits. Each data frame follows these
logical paths and provides a reliable way of transmitting data with less chance of data
loss.

Routing :
Routing refers to the process of directing a data packet from one node to another. It is
an autonomous process handled by the network devices to direct a data packet to its
intended destination. Note that, the node here refers to a network device called –
‘Router‘.. Routing is a crucial mechanism that transmits data from one location to
another across a network (Network type could be any like LAN, WAN, or MAN). The
process of routing involves making various routing decisions to ensure reliable &
efficient delivery off the data packet by finding the shortest path using various routing
metrics which we will be discussing in this article.

Routing of a data packet is done by analyzing the destination IP Address of the

packet. Look at the below image:

Source Node (Sender) sends the data packet on the network, embedding the IP in the
header of data packet.
The nearest router receives the data packet, and based on some metrics, further
routes the data packet to other routers.
Step-2 occurs recursively
ively till the data packet reaches its intended destination.

Routing
Routing is typically of 3 types, each serving their own purpose and offering different
functionalities.

Types-of-Routing
Types of Routing

1. Static Routing
Static routing is also called as “non-adaptive routing”. In this, routing configuration is
done manually by the network administrator. Let’s say for example, we have 5
different routes to transmit data from one node to another, so the network
administrator will have to manually enter the routing information by assessing all the
routes.

Network administrator has full control over the network, routing the data packets to
their concerned destinations
Routers will route packets to the destination configured manually the network
administrator.
Although this type of routing gives a fine-grained control over the routes, it may not be
suitable for large scale enterprise networks.
2. Dynamic Routing
Dynamic Routing is another type of routing in which routing is an autonomous
procedure without any human intervention. Packets are transmitted over a network
using various shortest path algorithms and pre-determined metrics. This type of
routing is majorly preferred in modern networks as it offers more flexibility and
versatile functionality.
It is also known as adaptive routing.
In this, the router adds a new routes to the routing table based on any changes made
in the topology of the network.
The autonomous procedure of routing helps in automating every routing operation
from adding to removing a route upon updates or any changes made to the network.
3. Default Routing
Default Routing is a routing technique in which a router is configured to transmit
packets to a default route that is, a gateway or next hop device if no specific path is
defined or found. It is commonly used when the network has single exit point. The IP
Router has the following address as the default route : 0.0.0.0/0.

Working Principle of Routing

Routing works by finding a shortest path from the source node to the destination node
across a network. Here’s step-by-step working of routing:
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Step1: Communication initiation
The first step that typically happens is, one node (client or server) initiates a
communication across a network using HTTP protocols.

Step2: Data Packets

The source device now breaks a big chunk of information into small data packets for
reliable and efficient transmission. This process is called is called de-assembling and
encapsulating the data payload. And then each data packet is labelled with the
destination node’s IP address.

Step3: Routing Table

Routing table is a logical data structure used to store the IP addresses and relevant
information regarding the nearest routers. The source node then looks up for the IP
addresses of all the nodes that can transmit the packet to its destination and selects
the shortest path using the shortest path algorithm and then routes accordingly.

Routing Table is stored in a router, a network device that determines the shortest path
and routes the data packet.

Step4: Hopping procedure

In the procedure or routing, the data packet will undergo many hops across various
different nodes in a network till it reaches its final destination node. Hop-count is
defined as the number of nodes required to traverse through to finally reach the
intended destination node. This hopping procedure has a certain criteria defined for
every data packet, there’s a limited number of hops a packet can take if the packet
exceeds that, then its considered to be lost and it is retransmitted.

Step5: Reaching the destination node

Once all the data packets reach their intended destination node, they re-assemble
and transform into complete information that was sent by the sender (source node).
The receiver will perform various error checking mechanism to verify the authenticity
of the data packets.

Overall, the data packet will be transmitted over least hop-count path as well as the
path on which there is less traffic to prevent packet loss.

Routing-Working
Working of Routing

In the above image, we have 3 major components

Sender 47
Receiver
Routers
The shortest path is highlighted in red, the path with least hop-count. As we can see,
there are multiple paths from source to node but if all the appropriate metrics are
satisfied, the data packets will be transmitted through the shortest path (highlighted in
red).

Routing Metrics and Protocols

The purpose of routing protocols is to learn about all the available paths to route data
packets, build routing table and take routing decisions based on some specified
metrics. There are two primary types of routing protocols rest of them ideate from
these two only.

1. Distance Vector Routing

In this type of routing protocol, all the nodes that are a part of the network advertise
their routing table to their adjacent nodes (nodes that are directly connected to each
other) at regular intervals. With each router getting updated at regular intervals, it

may take time for all the nodes to have the same accurate network view.

Uses fixed length sub-net, not suitable for scaling.

Algorithm used: Bellman Ford Algorithm to find the shortest path.
2. Link State Routing
Link State Routing is another type of dynamic routing protocol in which routes
advertise their updated routing tables only when some new updates are added. This
results in effective use of bandwidth. All the routers keep exchanging the information
dynamically regarding different links such as cost and hop count to find the best
possible path.

Uses variable length sub-net mask, which is scalable and uses addressing more
effectively.
Algorithm used: Djikstra’s Algorithm to find the shortest path.
Let’s look at the metrics used to measure the cost to travel one node to another :-

1. Hop Count: Hop count refers to the number of nodes a data packet has to traverse
to reach its intended destination. Transmitting from one node to another node counts
as 1 – hop count. The goal is to minimize the hop count and find the shortest path.

2. Bandwidth Consumption: Bandwidth is the ability of a network to transmit data

typically measured in (Kilobits per second)kbps, mbps(Megabits per second) or Gbps
(Gigabits per second). The bandwidth depends on a number of factors such as – the
volume of data, traffic on a network, network speed etc. Routing decision is made in
a way to ensure efficient bandwidth consumption.
3. Delay: Delay is the time it takes for a data packet to travel from source node to its
destination node. There are different types of delay such as – propagation delay,
transmission delay, queing delay.

4. Load: Load refers to the network traffic on a certain path in the context of routing. A
data packet will be routed to the path with lesser load so that it reaches its destination
in the specified time.

4. Reliability: Reliability refers to the assured delivery of the data packet to its
intended destination although there are certain other factors, the data
packet is routed in such a way so that it reaches its destination. The
stability and availability of the link in the network is looked over before
routing the data packet from a specific path.

Network Troubleshooting is a way to maintain your computer network, ensuring

optimal performance, and addressing issues that may disrupt connectivity. when any
problems arise, network administrators and IT professionals use tools such as Ping,
Traceroute, and PathPing to identify and solve a problem.
Network Troubleshooting Tools
In addition to user reports and firsthand experience on the network, there are a
number of tools available for you to use when it comes to diagnosing and treating
network issues. These tools may exist in the computer’s operating system itself, as
standalone software applications or as hardware tools that you can use to
troubleshoot a network.

Learn more about these topics in the Official CompTIA Network+ Study Guide.

Command-Line Tools
On Windows PCs, the command prompt can be accessed by searching for it in the
start menu or by typing “cmd” into the Run window. On a Linux system, you can press
Ctrl + Alt + T to open the command line.

The following commands can be entered into the command prompt one at a time to
reveal specific information about the network status:

ping — A TCP/IP utility that transmits a datagram to another host, specified in the
command. If the network is functioning properly, the receiving host returns the
datagram.

tracert/traceroute —A TCP/IP utility that determines the route data takes to get to a
particular destination. This tool can help you to determine where you are losing
packets in the network, helping to identify problems.
nslookup — A DNS utility that displays the IP address of a hostname or vice versa.
This tool is useful for identifying problems involving DNS name resolution.
ipconfig — A Windows TCP/IP utility that verifies network settings and connections. It
can tell you a host’s IP address, subnet mask and default gateway, alongside other
important network information.
ifconfig — A Linux or UNIX TCP/IP utility that displays the current network interface
configuration and enables you to assign an IP address to a network interface. Like
ipconfig on Windows, this command will tell you vital information about the network
and its status.
iptables — A Linux firewall program that protects a network. You can use this tool if
you suspect that your firewall may be too restrictive or too lenient.
netstat — A utility that shows the status of each active network connection. This tool
is useful for finding out what services are running on a particular system.
tcpdump — A utility that is used to obtain packet information from a query string sent
to the network interface. It’s available for free on Linux but can be downloaded as a
command for Windows.
pathping — A TCP/IP command that provides information about latency and packet
loss on a network. It can help you troubleshoot issues related to network packet loss.
nmap — A utility that can scan the entire network for various ports and the services
that are running on them. You can use it to monitor remote network connections and
get specific information about the network.
route — A command that enables manual updating of the routing table. It can be used
to troubleshoot static routing problems in a network.
arp — A utility that supports the Address Resolution Protocol (ARP) service of the
TCP/IP protocol suite. It lets the network admin view the ARP cache and add or

delete cache entries. It can be used to address problems having to do with specific
connections between a workstation and a host.
dig — A Linux or UNIX command-line tool that will display name server information. It
can be used to troubleshoot problems in DNS name resolution.
Ping is a command that sends a small packet of data to any network device and waits
for its response. Traceroute traces the route from source to destination and it helps
identify any delay or bottleneck. PathPing combines the functionality of both Ping and
Traceroute commands to troubleshoot the network. In this article, we will learn about
Ping, Traceroute, and PathPing tools, and how to use them to troubleshoot the
network.

Ping
A Ping stands for Packet Internet Groper. It is a widely used command for identifying
connectivity between two network connections. It uses Internet Control Message
Protocol (ICMP) to send a request to the target host and wait for a response. It
measures the round-trip time for data packets to travel from the source to the
destination and back
Explanation

It shows that we have sent 4 request (packet) and received acknowledgment of all the
requests and there is Zero loss. and It shows a minimum, maximum and average
round trip time in milliseconds.

Traceroute
Traceroute is also called as a tracert. It traces the route from source to the
destination. It is achieved by using ICMP to send a request. It revels the all routers
between source and destination by displaying their IP Address to detect where the
packet loss or latency occurs.

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Explanation

Each lines shows a route with round

round-trip
trip time. the first line shows a router has
216.58.196.206 address a and round-trip
trip time is 1ms. and the second line has a
timeout. This means that the router at hop 3 did not response to the ICMP request
within the time limit

PathPing
PathPing command is a combination of ping and tracert command. It sends request to
each routers
outers that comes between source and destination and compute result based
on response from each router. It provide continues monitoring of the network path
which allow network administrator to observe changes in performance.

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 Explanation
It shows Hop 0, Hop 1 , Hop 2 is a source with no packet loss, with round-time

Network Troubleshooting Applications

In addition to command-line tools, there are also a number of standalone applications
that can be used to determine the status of a network and to troubleshoot issues.
Some of these applications may be included in the system that you are working with,
while others may need to be installed separately.
• Packet Sniffer — Provides a comprehensive view of a given
network. You can use this application to analyze traffic on the network, figure out
which ports are open and identify network vulnerabilities.
• Port Scanner — Looks for open ports on the target device and
gathers information, including whether the port is open or closed, what services are
running on a given port and information about the operating system on that machine.
This application can be used to figure out which ports are in use and identify points in
a network that could be vulnerable to outside attacks.
• Protocol Analyzer — Integrates diagnostic and reporting
capabilities to provide a comprehensive view of an organization's network. You can
use analyzers to troubleshoot network problems and detect intrusions into your
network.
• Wi-Fi Analyzer — Detects devices and points of interference
in a Wi-Fi signal. This tool can help you to troubleshoot issues in network connectivity
over a wireless network.
• Bandwidth Speed Tester — Tests the bandwidth and latency
of a user’s internet connection. This application is typically accessed through a third-
party website and can be used to confirm user reports about slow connections or
download speeds
 Experirment-14
AIM :Study of scaling of networks ,design verities of LAN and forward of traffic
Apparatus (Software): Command Prompt And Packet Tracer.

Topology Diagram

Objectives

 Determine the cable types to use to connect all devices to the switch.
 Add appropriate modules to switches and routers.
 Connect the devices to the switch using the appropriate cable types.

Background / Preparation
The results of a site survey for an ISP customer indicate that the customer needs to
upgrade the LAN to include
a new standalone switch. The network has an existing router (Router0) and a Linksys
300N router. It is
necessary to determine which interfaces are needed on the new switch to provide
connectivity to the router, the
Linksys device, and the customer PCs. The customer wants to use copper cabling.
Note: Links created with the switch may take a minute to change from amber to
green. Switch between
Simulation mode and Realtime mode to speed up this process.

Step 1: Determine the required connectivity options.

a. Click Router0. Using the information in the Physical Device View window on the
Physical tab,
determine what type of interface is available on the router to connect to the new
switch.
Hint: Place the mouse pointer on the interface to display the interface type. Click on
the interface type
to display a description of the interface.
Which interface is available on the router to connect to the new switch? What type of
cable is required?
-------------------------------------------------------------------------------------------
Click the Linksys 300N. Using the picture on the Physical tab, determine what type of
cable is necessary to connect
to the new switch.
Which interface is available on the Linksys 300N to connect to the new switch? What
type of cable is required?

Step 2: Configure the new switch with the required options.

a. Click Switch0.
On the Physical tab, explore each switch module available under the Modules option.
Choose the appropriate interfaces to connect to Router0 and the Linksys 300N router.
Choose the appropriate interfaces to connect to the existing PCs.
Power down the switch using the power button in the Physical Device View window
on the Physical tab.
Choose the appropriate modules for the switch. Add the four necessary interfaces to
the switch.
Power up the switch using the power button shown in the Physical Device View
window on the Physical tab.
Click the Config tab. Select each interface and ensure that the On box is checked.
Step 3: Connect the router to the switch.

a. Using the appropriate cable, connect the router port to the first available switch
port. Click the Config
tab on the router. Select the interface and ensure that the On box is checked.
b. Verify connectivity. A green light appears on each end of the link if the cabling is
correct.
Step 4: Connect the Linksys 300N to the switch.

a. Using the appropriate cable, connect the Linksys 300N to the second available port
on the newswitch.
Verify connectivity. A green light appears on each end of the link if the cabling is
correct.
Step 5: Connect the PCs to the switch.

a. Using the appropriate cable, connect the existing PCs to the new switch.
b. Verify connectivity. A green light appears on each end of the links if the cabling is
correct.
c. Click the Check Results button at the bottom of this instruction window to check
your work

56
 Practical 15
Aim of experiment: Study WAN concepts and Configure and forward
Traffic in WAN
Apparatus (Software): Command Prompt And Packet Tracer.

Objective

The show commands are very powerful commands for troubleshooting and
monitoring networks. They

give a static image of the network at a given time. The use of a variety of show
commands will give a

clear picture of how the networking is communicating and transferring data.

Background / Preparation

The physical topology of the network has been designed using Frame Relay. To test
the network

connectivity, use a variety of show commands.

57
Required file: Examining WAN Connections.pka

Step 1: Examine the configuration of Branch1 and Branch2.

a. Click on Branch1 and use various show commands to view the connectivity to the
network.

b. Use the show running-configuration command to view the router configuration.

c. Use the show ip interface brief command to view the status of the interfaces.

d. Use the various show frame-relay map, show frame-relay pvc, and show frame-
relay lmi

commands to see the status of the Frame-relay circuit.

e. Click on Branch 2 and use various show commands to view the connectivity to the
network.

f. Use the show running-configuration command to view the router configuration.

g. Use the show ip interface brief command to view the status of the interfaces.

h. Use the various show frame-relay map, show frame-relay pvc, and show frame-
relay lmi

commands to see the status of the Frame-relay circuit.

Step 2: Examine the configuration of Main.

a. Click on Main and use a variety of show commands to view the connectivity to the
network.

b. Use the show running-configuration command to view the router configuration.

c. Use the show ip interface brief command to view the status of the interfaces.

d. To view the status of the frame-relay configurations use the show frame-relay lmi,
show framerelay map, and show frame-relay pvc commands

58
 Practical 16

AIM: Configure IPv4 and IPv6 and learn Quality, security and other
services
Configure IPv4 and IPv6 (win 10& 11)
First, open the Settings app: a quick way to do that is to push the Settings
Settin
button from the Start Menu or to press Windows + I on your keyboard
simultaneously. In the Settings app, open the Network & Internet category.

On the left sidebar, select your network type. If you’re using a wireless card, click or
tap on Wi-Fi. If you’re using a wired connection, go to Ethernet. On the right side of
the window, click or tap on the name of your network connection.

59
Scroll down on your network connection details page until you find the section called
IP settings. Then, click or tap on Edit, under IP assignment.

60
The Settings app now shows the “Edit IP settings” dialog. This is where you can change the
IP address of your computer or device. If you want the IP address of your Windows 10 PC
to be assigned
signed automatically by your router, select Automatic (DHCP). This is also called a
dynamic IP address.

61
If you want to set your own static IP address, select Manual and then enable the IPv4
and/or IPv6 switches, depending on what internet protocols you want to use. Note that each
of them has its own distinct IP address, so you must enter the required details for both IPv4
and IPv6 if you choose to enable both.

62
 To change your IP address to a static one, regardless of whwhether
ether you set it for
your IPv4 or IPv6 protocols, you have to enter the following details:
 IP address:: Type the static IP address that you want to use. For example, I
want to change the IP address (IPv4) of my Windows 10 PC to 192.168.50.10.
192.1
 Subnet prefix length:: Type the prefix length that determines the size of the subnet.
For example, I configured my router to use a subnet mask of 255.255.255.0, which means
that I have to enter a “Subnet prefix length” of 24 (the numberr of 1 bits in the netmask). If I
had a subnet mask of 255.255.0.0, the prefix length would have been 16, and so on.
 Gateway:: Type the IP address of your router. In my case, that’s 192.168.50.1.

63
The Preferred DNS and Alternate DNS settin
settings
gs are not mandatory - if you leave
them blank, they are automatically assigned by your router. However, if you
want to change them too, you can do so. TIP: Here are more ways to change
DNS settings in Windows.

Once you’ve entered all the details, click o

orr tap on Save, and Windows 10
changes your IP address.

64
MPORTANT: If you choose to use a static IP address, ensure all the details you
enter are correct; otherwise, your Windows 10 PC lloses
oses internet connectivity. If
that happens, change your IP address back to Automatic (DHCP) so that your
router can change it to something that works.

Win 11:

Open the Settings app: a quick way to do that is to use its Pinned shortcut from
the Start Menu
nu or press Windows + I on your keyboard. Once you’ve opened it,
select Network & internet on the left sidebar.

65
The Network & internet settings in Windows 11

On the right,
ght, click or tap on the type of network you’re currently using. If you
connect to the internet (or local area network) using a wireless card, select Wi-Wi
Fi. If you’re accessing the internet (or LAN) using a wired connection, click or
tap on Ethernet.

66
Wi-Fi
Fi or Ethernet network connection
Next, click or tap on the properties entry of your network connection.

67
The network's properties
This opens a page filled with details about the selec
selected
ted network connection. On
it, scroll down and click or tap the Edit button next to IP assignment.

The Edit button next to IP assignment

As a result, the Settings app loads a dialog called “Edit network IP settings,”
where you can set the IP address of yyour
our Windows 11 PC. If you want to use a
dynamic IP address assigned automatically by the router, choose Automatic
(DHCP).

68
Let Windows 11 get an IP address automatically via DHCP
If you want to set a static IP address for your Windows 11 computer,
c select
Manual. Then, turn on the IPv4 and/or IPv6 switches, depending on the internet
protocols you intend to use. Keep in mind that each one needs a distinct IP
address, so you’ll have to specify details for both IPv4 and IPv6 if you decide to
enable both.

69
Edit IP settings to change the IPv4 address in Windows 11

In order to set a static IP address for either IPv4 or IPv6, you have to provide
the next details:

IP address:: Enter the static IP address you want to use. For instance,
inst I’m
changing the IP address (IPv4) of my Windows 11 computer to 192.168.50.10.
Subnet mask:: Type the subnet mask used by your network. For example, I’ve
configured my mesh Wi Wi-Fi
Fi to use a 255.255.255.0 subnet mask, which means
that this is the number sequence I need to enter.
Gateway:: Specify the IP address of your router or mesh Wi-Fi.
Wi In my case,
that’s 192.168.50.1.

70
Setting a static IP address in Windows 11
These are all the settings you need to configure in order to change your IP
address in Windows 11. However, there are two more options in the “Edit
network IP settings” dialog: Preferred DNS and Alternate DNS. While not
necessarily required (if they’re blank, your router automatically assigns
assig them),
you can change them, too, if you want. Here are more details about DNS: What
is DNS? How is it useful?.

Once you’ve finished editing your network IP settings, click or tap the Save
button, and your IP address is immediately changed in Windows 11. 11

71
How to set a static IP address in Windows 11
IMPORTANT: If you’ve changed your IP address and your Windows 11 PC lost
internet connectivity, you’ve probably entered an incorrect IP address. In that
case, switch back to using Automatic (DHCP
(DHCP)) to let your router assign a new
one for your computer, one that works.

IMPORTANT: If you’ve changed your IP address and your Windows 11 PC lost

internet connectivity, you’ve probably entered an incorrect IP address. In that
case, switch back to using Au
Automatic
tomatic (DHCP) to let your router assign a new
one for your computer, one that works.

To set up IPv6 in Windows, you can follow these steps

Steps of configure ip6 :

Click Start, click Control Panel, and then double

double-click
click Network Connections.
Right-click any local area connection, and then click Properties.
Click Install.
Click Protocol, and then click Add.
Click Microsoft TCP/IP version 6, and then click OK.
Click Close to save changes to your network connection.
Alternatively, you can enable IPv6 by going to Settings > Network & Internet >
Properties > Edit > Manual > Enable IPv6 > Populate your settings54.

These steps assign ip6 using picture:-

1 Open the Control Panel (icons view), and click/tap on the Network and
Sharing Center icon.

2 Click/tap on the Change adapter settings link on the left side, and close the
Network and Sharing Center if you like. (see screenshot below)

3 Right click or press and hold on the network adapter (ex: "Wi-Fi") you want,
and click/tap on Properties. (see screenshot below)

4 Check (enable) or uncheck (disable) the Internet Protocol Version 6

(TCP/IPv6) box for what you want to do, and click/tap on OK. (see screenshot
below)

73
5 When finished, you can close Network Connections if you like.

2. Quality of Service (QoS):

Traffic Prioritization: Configure QoS to prioritize certain types of traffic (voice,
video, critical applications) over others for better performance.
Bandwidth Allocation: Use QoS mechanisms like traffic shaping and policing to
allocate and manage bandwidth effectivel
3. Network Security Services:
IPv4 and IPv6 Security Measures:
Firewalls: Configure firewalls on routers or dedicated devices to filter traffic

based on security policies.

Access Control Lists (ACLs): Set up ACLs to control traffic flow and restrict
access to specific IP addresses or protocols.
4. Other Network Services:
IPv4 and IPv6 Service Implementations:
DNS: Configure DNS servers for both IPv4 and IPv6 to resolve domain names.
DHCPv6: Implement DHCPv6 for dynamic IPv6 address assignment.
NAT (Network Address Translation): Configure NAT for IPv4 to map private IP
addresses to a public IP address.

74
 Practical 17
AIM: Learn Network programming

network programming concerning Python. But for this, the programmer must
have basic knowledge of:

 Low-Level Programming using sockets

 Data encoding
 HTTP and web-programming
 High-Level client modules
 Basic networking terms and their concepts etc.

PYTHON NETWORK SERVICES:

There are two levels of network service access in Python. These are:

 Low-Level Access
 High-Level Access
In the first case, programmers can use and access the basic socket support for
the operating system using Python's libraries, and programmers can implement
both connection-less and connection-oriented protocols for programming.

Application-level network protocols can also be accessed using high-level

access provided by Python libraries. These protocols are HTTP, FTP, etc.

socket :

A socket is the end-point in a flow of communication between two programs or

communication channels operating over a network. They are created using a
set of programming requests called socket API (Application Programming
Interface). Python's socket library offers classes for handling common transports
as a generic interface.

Sockets use protocols for determining the connection type for port-to-port
communication between client and server machines. The protocols are used for:

Domain Name Servers (DNS)

IP addressing
E-mail
FTP (File Transfer Protocol) etc...
Python has a socket method that let programmers' set-up different types o
 socket virtually. The syntax for the socket method is:

Python has a socket method that let programmers' set-up different types of
socket virtually. The syntax for the socket method is:

SYNTAX:
g = socket.socket (socket_family, type_of_socket, protocol=value)

For example, if we want to establish a TCP socket, we can write the following
code snippet:

Here's another example to establish a UDP socket. The code is:

After you defined the socket, you can use several methods to manage the
connections. Some of the important server socket methods are:

listen(): is used to establish and start TCP listener.

bind(): is used to bind-address (host-name, port number) to the socket.

accept(): is used to TCP client connection until the connection arrives.

connect(): is used to initiate TCP server connection.

send(): is used to send TCP messages.

76
 recv(): is used to receive TCP messages.

sendto(): is used to send UDP messages

close(): is used to close a socket.

Network program using python:

Save the file with filename - tcpserver.py

It will open a web server at port 60. In the above program, everything you write in the
client goes to the server.

Now a simple Python client script:

77
Sending messages back and forth using different basic protocols is simple and
straightforward. It shows that programming takes a significant role n client-server
architecture where the client makes data request to a server, and the server replies to
those machines.

78
 Practical 18
AIM: Troubles shoot Networks

Network Troubleshooting Scenarios for Intermittent Network Problems

Intermittent network problems can be frustrating and challenging to troubleshoot

because they occur sporadically and may not be immediately apparent. Here are
some network troubleshooting scenarios to consider when dealing with intermittent
network problems:

 Loose or Damaged Cables: Physical issues with network cables, such as loose
connections or damaged cables, can lead to intermittent connectivity problems.
Inspect cables and connectors for any visible damage or loose connections.
 Wireless Interference: In a wireless network, interference from other wireless
devices, neighboring networks, or electronic devices can cause intermittent
connectivity issues. Conduct a wireless site survey and identify potential
sources of interference.
 DHCP Issues: Problems with the DHCP (Dynamic Host Configuration Protocol)
server can result in intermittent IP address assignment, leading to connectivity
problems. Check DHCP logs and ensure the DHCP server is properly
configured and responsive.
 DNS Problems: DNS (Domain Name System) issues can cause intermittent
access to websites and services. Verify DNS settings and check for any DNS-
related errors in the logs.
 Misconfigured Firewall or Security Software: Overly aggressive firewall rules or
misconfigured security software can block legitimate traffic and cause
 intermittent connectivity problems. Review firewall and security software
settings for potential issues.
 Bandwidth Saturation: Periodic spikes in network traffic can saturate the
available bandwidth and cause intermittent connectivity problems. Monitor
network traffic patterns to identify potential bandwidth saturation points.
 Network Device Overheating: Overheating of network devices, such as routers
or switches, can lead to intermittent network outages or services outages (ex.
 Microsoft Teams outages). Ensure that network equipment is properly ventilated
and not subjected to excessive heat.
 Firmware or Software Bugs: Firmware or software bugs in network devices can
cause intermittent problems. Check for firmware updates and apply the latest
patches from the manufacturer.
 Duplicate IP Addresses: Duplicate IP addresses on the network can result in
intermittent connectivity issues. Use network scanning tools to check for
duplicate IP addresses.

 Routing Issues: Incorrect or unstable routing configurations can lead to

intermittent connectivity problems. Review routing tables and ensure they are
correctly configured.
 Power Fluctuations: Power fluctuations or intermittent power supply issues can
cause network devices to reboot or lose connectivity. Use uninterrupted power
supply (UPS) units to provide stable power to critical network equipment.
 Network Congestion: During periods of high network usage, congestion can
cause intermittent performance issues. Monitor network traffic during peak
hours and consider implementing Quality of Service (QoS) policies.
 Malware or Security Breaches: Malware infections or security breaches can
cause intermittent network disruptions. Regularly scan for malware and
implement robust security measures.

Network Problem #2. High Bandwidth Usage

Bandwidth is the maximum amount of data transmitted over an Internet connection in

a given amount of time.

It refers to a network’s capacity to transfer data between devices or the Internet within
a given span of time. Bandwidth is often mistaken for Internet speed when it's actually
the volume of information that can be sent over a connection in a measured amount
of time – calculated in megabits per second (Mbps).

Higher bandwidth allows data to be transferred across your network at a faster rate
and can sustain a larger number of connected devices all at once - but it can
significantly impact network performance and user experienc.
It occurs when a considerable amount of data is being transmitted over the network,
leading to increased congestion and potential bottlenecks. When someone or
something, like a large application, on your network is monopolizing your bandwidth
by downloading gigabytes worth of data, it creates a congestion in your network.

This excessive data transfer can result from various factors, both legitimate and non-
legitimate, and it's essential to identify and address the root cause to maintain a
smoothly functioning network.

high bandwidth usage - Common Network Problems

I. The Consequences of High Bandwidth Usage:

80
 Network Congestion: Network congestion caused by high bandwidth usage,
also runs the risk of leaving insufficient amounts of bandwidth for other parts of
your network that need it. When this happens, you may start experiencing
problems like slow download speed over the Internet.
 Slow Network Performance: High bandwidth consumption can lead to slower
network speeds, causing delays in accessing resources and data.
 Latency and Packet Loss: As network resources become saturated, latency
(delay) and packet loss may increase, affecting real-time applications like VoIP
or video conferencing.
 Reduced Productivity: Sluggish network performance can hamper productivity,
as users may experience delays in performing critical tasks.
 Increased Costs: Excessive bandwidth usage can lead to overage charges from
internet service providers (ISPs) if they exceed the Internet SLA, or the need to
upgrade to higher-tier plans, resulting in higher operational costs. Network
Downtime: In extreme cases, high bandwidth usage can lead to network
outages if the infrastructure is not equipped to handle the traffic load.

II. The Causes of High Bandwidth

 Large Downloads: Downloads consisting of large files that are being placed on
your computer's harddrive from the Internet, like file transfers or backups, can
drastically increase bandwidth usage. The more bytes the file contains, the
higher your bandwidth usage.
 Latency: Latency refers to the time it takes for a data packet to reach its
destination in a network, can. Consistent delays or odd spikes in delay time are
signs of major performance issues and can affect bandwidth time.
 Packet Loss: Packet Loss occurs when a data packet is dropped during its
journey across a network and never makes it to its final destination and back. It
can cause a great deal of problems depending on how much of the packet does
not go through and how often it occurs.
 Video Streaming: Streaming videos from the Internet is a more common cause
of high bandwidth usage. Streaming video in 7k can take up to 200 times more
bandwidth than audio streaming.
 Large Applications: Different applications have different requirements.
Applications that require Internet connection, like programs for web
development, email, computer games, etc. require a lot of bandwidth to function
and can therefore increase your bandwidth usage.
 File Sharing: There are programs that allow users to share files from computer-
to-computer connection over the Internet. These programs can result in high
 bandwidth usage as they require you to download and transfer large files, with
large amounts of data, over the Internet.

 Legitimate Traffic: Legitimate high-bandwidth activities, such as large file

transfers, video conferencing, cloud backups, and software updates, can
consume significant network resources. While these activities are essential for
business operations, they can lead to congestion during peak usage times.
 Malware and Unauthorized Activities: Malicious software or unauthorized users
can exploit network resources, leading to unanticipated spikes in bandwidth
usage. Botnets, malware downloads, or unauthorized file sharing can cause
significant disruptions.
 Background Updates: Automatic updates for operating systems, applications,
and antivirus software can utilize bandwidth without user intervention. These
updates can coincide and cause temporary surges in bandwidth usage.
 P2P File Sharing: Peer-to-peer (P2P) file-sharing applications can lead to high
bandwidth usage as users upload and download files directly from each other.

How to Measure Bandwidth: Techniques for Precise Network Measurement

How to Measure Bandwidth for Precise Network Measurement

How to measure bandwidth, identify issues & optimize network performance. Use
Obkio's Network Performance Monitoring tool for easy bandwidth monitoring.

Learn more right arrow

III. How to Identify & Troubleshoot High Bandwidth Usage

 Network Monitoring: Use a network monitoring tool like Obkio to measure

bandwidth and track bandwidth usage in real-time. Observe usage patterns and
identify any unusual spikes or sustained high traffic.
 Application Analysis: Analyze the bandwidth consumption of various
applications to identify resource-intensive processes. This will help you pinpoint
which applications are contributing the most to high usage.
 Quality of Service (QoS) Policies: Implement QoS policies to prioritize critical
applications and services over less important ones. This ensures that essential
operations receive sufficient bandwidth even during peak usage.
 Bandwidth Optimization: Utilize bandwidth optimization techniques such as
compression, caching, or content filtering to reduce overall data transfer.
  Traffic Shaping: Employ traffic shaping mechanisms to control and limit
bandwidth usage for specific applications or users.
 Identify Malware or Unauthorized Activity: Regularly scan for malware and
unauthorized users on the network, and implement security measures to
prevent exploitation.

By proactively identifying and addressing high bandwidth usage, businesses can

maintain a responsive and efficient network, enhancing overall productivity and user
satisfaction.

IV. Network Troubleshooting Scenarios for High Bandwidth Usage

High bandwidth usage can lead to various network performance issues and can be
caused by several factors. Here are some network troubleshooting scenarios to
investigate when experiencing high bandwidth usage:

 Malware or Botnet Activity: Malware-infected devices or botnet activity can

consume significant bandwidth as they may be involved in malicious activities
such as sending spam emails or participating in Distributed Denial of Service
(DDoS) attacks. Use network monitoring tools to identify suspicious traffic
patterns and isolate infected devices.
 Streaming and Video Content: High-quality video streaming or large file
downloads can consume substantial bandwidth. Check for excessive video
streaming or downloads that might be impacting the network, especially during
peak hours.
 Cloud Services or Backups: Cloud services and data backups can utilize
substantial bandwidth, especially if they are scheduled to occur during business
hours. Check the bandwidth consumption of cloud services (with Microsoft
Cloud Monitoring for example) and backup applications to see if adjustments
can be made to their schedules.
 Peer-to-Peer (P2P) File Sharing: P2P file sharing applications can consume a
significant amount of bandwidth, especially if multiple users are involved.
Identify and control P2P traffic on the network.
 Software Updates: Automatic software updates from operating systems and
applications can lead to sudden spikes in bandwidth usage. Ensure that
updates are scheduled during off-peak hours
 84
  Network Misconfiguration: Misconfigured network devices, such as routers or
switches, can lead to unnecessary broadcast/multicast traffic or loops that
cause high bandwidth usage. Verify the network configuration for any issues.
 Bandwidth-Intensive Applications: Some applications inherently consume more
bandwidth than others. Identify and analyze bandwidth usage by specific
applications and determine if any optimization or restriction is required.
 Virtual Local Area Networks (VLANs): Improperly configured VLANs can lead to
unnecessary traffic and high bandwidth usage. Review VLAN configurations to
ensure they are set up correctly.
 Wireless Network Interference: In a wireless network, interference from other
devices, neighboring networks, or non-Wi-Fi devices operating in the same
frequency range can cause high bandwidth utilization. Perform a wireless site
survey and optimize Wi-Fi settings.
 Data Backups and Replication: Data backup and replication processes between
geographically dispersed sites can consume significant bandwidth. Review
backup and replication schedules and consider using deduplication and
compression techniques.
 Denial of Service (DoS) Attacks: DoS attacks can overwhelm a network with an
excessive amount of traffic, leading to high bandwidth usage. Implement DoS
protection mechanisms and analyze traffic patterns for signs of an ongoing
attack.
 Internet of Things (IoT) Devices: The proliferation of IoT devices can contribute
to increased bandwidth consumption if they are transmitting large amounts of
data. Monitor IoT device traffic and assess their impact on overall bandwidth.

To troubleshoot high bandwidth usage, it is essential to use network monitoring tools

that provide insights into traffic patterns, application usage, and device behaviour, like
we mentioned in the last point. With this information, you can identify the root cause
of the problem and take appropriate measures to optimize network performance.

Network Problem #3. High CPU Usage

85
CPU, or “ Central Processing Unit”, is the primary component of a computer that
receives and processes instructions for operating systems and applications.

High CPU usage is another common network problem that can significantly impact
the performance and stability of a network. It occurs when the central processing unit
(CPU) of a network device, such as a router, switch, firewall, or server, is operating at
or near its maximum capacity. This can lead to various issues that affect the overall
network functionality and user experience.

With such a big job on its shoulders, the signs of high CPU usage on a network
device are a very troubling sign for many of us. As your network devices continue to
work harder to perform an increasing amount of tasks, it increases the chance that
things can go wrong.

Network Firewall CPU Monitoring Network Problems

86
I. The Consequences of High CPU Usage

 Sluggish Network Performance: High CPU usage can lead to delays in

processing network traffic, causing slow response times and increased latency.
 Packet Loss: When the CPU is overloaded, it may drop packets, resulting in
packet loss, which can degrade the quality of real-time applications like VoIP or
video conferencing.
 Network Downtime: In extreme cases, when the CPU is overwhelmed, the
device may become unresponsive, leading to network outages and disruptions.

Security Vulnerabilities: High CPU usage can leave network devices more vulnerable
to security threats as their ability to handle security tasks is compromised.

II. The Causes of High CPU Usage

The most common reason for high CPU usage occurs when your network becomes
bogged down by enormous amounts of traffic. CPU usage can increase drastically
when processes require more time to execute or when a larger number of network
packets are sent and received throughout your network.

There are a number of network devices such as switches that have hardware
components (ASICs or NPUs) that take charge and process packets super quickly.
For this equipment, the CPU usage is not linked to the amount of traffic.

For equipment that analyzes or manipulates traffic, like firewalls, that's a whole
different story. Depending on the features that you’ve enabled on your devices, the
CPU may be in the critical path of packet routing or forwarding. If overused, network
metrics like latency, jitter, and packet loss will increase, which will lead to significant
levels of network performance degradation.

In summary, some common causes include:

87
  Network Traffic Overload: A sudden surge in network traffic or sustained high
levels of data transfer can overwhelm the CPU, especially on devices handling
routing, switching, or security tasks.
 Network Security Operations: CPU usage may spike during security-related
activities such as deep packet inspection, intrusion detection, or denial-of-
service attack mitigation.
 Resource-Intensive Applications: CPU usage can be driven up by resource-
intensive applications running on servers or other network devices.
 Firmware/Software Bugs: Firmware or software bugs can cause abnormal CPU
usage, leading to unexpected behavior and degraded performance.

III. Troubleshoot High CPU Usage

It can sometimes be difficult to gather the right information about the actual use of
CPU. Several monitoring tools such as those included in the equipment's GUI or a
poorly configured monitoring tool can report an average value on the use of 8 cores or
over too long periods, such as every 5, 15 or 60 minutes. Which isn't enough - so to
identify and troubleshoot - you need to go further!

 Network Monitoring: Employ a network monitoring tool like Obkio to track CPU
utilization on network devices. Monitor CPU usage in real-time and set up alerts
for abnormally high CPU levels.

Identify Resource-Intensive Processes: Use monitoring tools and device logs to

identify resource-intensive processes or applications causing high CPU usage.

Adjust Network Traffic: Implement traffic shaping or quality of service (QoS) policies to
prioritize critical traffic and prevent CPU overload during periods of heavy network
usage.

Software/Firmware Updates: Regularly update device firmware and software to patch

bugs and optimize performance.

Optimize Applications: Consider optimizing resource-intensive applications or

distributing their load across multiple devices to reduce CPU burden.

Security Measures: Ensure that security policies and mechanisms are properly
configured to manage security-related CPU tasks effectively.
Device Upgrades: If network devices are consistently experiencing high CPU usage,
consider upgrading to more powerful hardware that can better handle the network
load.

By promptly identifying and resolving high CPU usage issues, businesses can
maintain a stable and responsive network environment, ensuring smooth operations
and enhanced user satisfaction.

IV. Network Troubleshooting Scenarios for High CPU Usage

High CPU usage in a network can impact the performance of network devices,
leading to sluggish response times, increased latency, and potential service
disruptions. Here are some network troubleshooting scenarios to consider when
dealing with high CPU usage on network devices:

Traffic Spikes: Monitor network traffic patterns to identify if there are sudden spikes in
data volume that could be causing high CPU usage. Investigate the source of the
increased traffic and determine if it is legitimate or if it indicates a potential DDoS
(Distributed Denial of Service) attack.

Packet Storms or Broadcast Storms: Excessive packet storms or broadcast storms

can overload the CPU of network devices. Use packet capture tools to analyze the
traffic and identify any sources of storms.

Malware or Botnet Activity: Malware infections on network devices can cause high
CPU utilization as they might be involved in malicious activities. Use security
monitoring tools to detect and remove malware from affected devices.

Routing or Switching Loops: Misconfigured or redundant routing or switching paths

can cause loops, leading to a significant increase in CPU usage. Review the device
configurations to ensure there are no loop-causing issues.

Software Bugs or Memory Leaks: Software bugs or memory leaks within the
operating system or network device firmware can cause CPU usage to spike over
time. Ensure that the network devices have the latest firmware updates and patches.
Network Device Overloading: If a network device is overloaded with traffic due to the
number of connected devices or the volume of data being processed, the CPU usage
can increase. Consider load balancing or upgrading the device to handle higher traffic
volumes.

Large Scale Routing Updates: In networks with dynamic routing protocols, large-scale
routing updates can cause CPU spikes on routers. Analyze routing update events and
fine-tune the routing protocols to minimize the impact.

Monitoring or Debugging Tools: Certain monitoring or debugging tools running on

network devices might consume a significant amount of CPU resources. Evaluate the
impact of such tools and adjust their configurations if necessary.

Quality of Service (QoS) Misconfiguration: Improperly configured QoS policies can

lead to unnecessary CPU usage as the devices attempt to classify and prioritize
traffic. Review and optimize QoS policies.

Hardware Issues: Faulty hardware components, such as failing CPUs or inadequate

cooling systems, can lead to high CPU usage. Perform hardware diagnostics and
replace any faulty components.

Intrusion Detection/Prevention Systems (IDS/IPS): IDS/IPS systems can be CPU-

intensive, especially when handling a large number of network packets. Fine-tune the
IDS/IPS settings and consider distributing the load across multiple devices if
applicable.

Virtualization Overhead: In virtualized environments, the hypervisor's CPU overhead

can impact network device performance. Adjust virtualization settings and resource
allocations as needed.

How to Measure CPU Usage in Networking

How to Measure CPU Usage in Networking

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performance with insights. Optimize with Obkio's Monitoring tool.

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Network Problem #4. Physical Connectivity Issues

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It may seem obvious, but some network issues may occur with the hardware outside
of the network.

When the time comes to troubleshoot network issues, our instinct is often to think
about the most complex situations, when sometimes the problem is actually very
simple and right in front of us.

Hardware problems like defective cables or connectors can generate network errors
on the network equipment to which it is connected. You may think that this problem is
due to a network outage or network failure, or Internet connection problem, but it’s
actually because you have a broken or malfunctioning cable.

This can also occur outside of the LAN network. If a copper cable, or fiber-optic cable
is damaged, it will likely reduce the amount of data that can go through it without any
packet loss.

I. The Consequences of Physical Connectivity Issues

Physical connectivity problems can manifest in various ways, leading to network

outages, slow data transfer, or intermittent connectivity.

Network Outages: A complete loss of physical connectivity can lead to network

outages, preventing users from accessing network resources.

Intermittent Connectivity: Loose or damaged cables may cause intermittent

connectivity issues, resulting in unreliable network access.

Slow Data Transfer: Poor physical connections can lead to data transmission errors
and retransmissions, slowing down data transfer rates.

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Increased Downtime*: The time spent identifying and resolving physical connectivity
issues can lead to increased network downtime and reduced productivity.

II. The Causes of Physical Connectivity Issues

Loose or Damaged Cables: Loose, damaged, or improperly connected cables can

lead to signal loss and intermittent connectivity. Cables that are bent, frayed, or
crushed may not transmit data effectively.

Faulty Connectors: Connectors that are not securely attached or have bent pins can
result in poor connections between devices, leading to data transmission issues.

Cable Length: Using cables that exceed their maximum recommended length can
lead to signal degradation and data loss.

Poorly Crimped or Terminated Cables: Improperly crimped or terminated cables may

cause signal interference and connectivity problems.

Network Device Issues: Faulty network interface cards (NICs) or malfunctioning ports
on switches or routers can cause physical connectivity problems.

Environmental Factors: External factors such as water damage, extreme

temperatures, or physical disturbances can impact network cables and connectors.

III. How to Identify & Troubleshoot Physical Connectivity Issues

Network Monitoring: Checking every cable one by one can be repetitive, and can take
a large amount of time out of your day. A simple way to monitor cables on a defective
connector is to have a network performance monitoring software, like Obkio, that will
measure network errors on all network interfaces and warn you if any problems arise.

Visual Inspection: Perform a physical inspection of cables, connectors, and network

devices to identify any visible signs of damage or loose connections.

Cable Testing: Use cable testers to check for continuity and proper termination of
network cables. Swap Cables and Connectors: If possible, try replacing suspect
cables and connectors with known-good ones to determine if the issue persists.

Check Device Indicators: Examine network device indicators, such as LED lights, to
see if they indicate any connectivity or link issues.
Environmental Assessment: Ensure that network equipment is kept in suitable
environmental conditions, free from water damage, extreme temperatures, and
physical obstructions.

Label and Organize Cables: Properly label and organize network cables to prevent
accidental disconnections and make troubleshooting easier.

Update Firmware and Drivers: Ensure that network devices have up-to-date firmware
and drivers to minimize the risk of hardware-related issues.

How to Troubleshoot Network Issues: Unleash Your Inner IT Hero

How to Troubleshoot Network Issues: Unleash Your Inner IT Hero

Learn how to troubleshoot network issues by identifying where, what, why network
problems occur with Network Troubleshooting tools.

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IV. Network Troubleshooting Scenarios for Physical Connectivity Issues

Physical connectivity issues can disrupt network communication and lead to various
network problems. Troubleshooting physical connectivity issues requires a systematic
approach and attention to detail. Here are some network troubleshooting scenarios to
consider when dealing with physical connectivity issues:

Check Physical Connections: Verify that all network cables, connectors, and ports are
properly connected and securely seated. Ensure that Ethernet cables are not
damaged and have all pins intact.

Swap Cables and Ports: If possible, swap suspect cables with known-working ones
and test different network ports on the devices to rule out faulty cables or ports.

Check Link Lights: Observe the link lights on network devices (routers, switches, and
network interface cards) to determine if the devices are detecting link signals. If link
lights are not active, it could indicate a physical connectivity problem.
Inspect Patch Panels and Wall Outlets: In structured cabling systems, examine patch
panels and wall outlets to ensure cables are correctly terminated and properly
labeled.

Use Cable Testers: Cable testers can help identify faulty cables, open circuits, or
short circuits. Use a cable tester to check the integrity of network cables.

Check Power Over Ethernet (PoE): For PoE devices, ensure that power is being
supplied correctly over the Ethernet cables.

Verify Power Status: Check the power status of network devices to ensure they are
powered on and functioning correctly.

Check Physical Damage or Environmental Factors: Look for physical damage to

network cables caused by bending, crushing, or exposure to environmental elements.
Address any environmental factors that might be affecting the cables, such as
excessive heat or moisture.

Review Network Topology: Review the network topology to ensure that cables are
appropriately connected between devices and network segments.

Test Connectivity with Known Devices: Test connectivity with known working devices
to isolate the issue to specific network segments or components.

Check Wiring Standards: Ensure that network cabling adheres to appropriate wiring
standards (e.g., TIA/EIA 568) and that cables are of the correct category (e.g., Cat 5e,
Cat 6, etc.) for the required network speeds.

Check Cable Lengths: Verify that the cable lengths do not exceed the maximum
allowed length for the chosen cable category and network technology (e.g., Ethernet
has specific cable length limits).

Inspect Network Devices' LEDs: Network devices like switches and routers often have
LEDs that indicate port activity and speed. Observe these LEDs to identify any
abnormal behavior.

Check Physical Security: Ensure that physical access to network devices and cables
is restricted to authorized personnel to prevent accidental or intentional
disconnections.

Consider EMI/RFI Interference: Electromagnetic Interference (EMI) or Radio-

Frequency Interference (RFI) from nearby electrical devices can affect network
connectivity. Isolate network devices from potential sources of interference
Inspect Fiber Optic Connections: If your network uses fiber optic cables, check the
connectors and fiber ends for any dirt, damage, or misalignment.

Network Problem #5. Malfunctioning Devices or Equipment

Sometimes, network issues occur within network equipment or devices like Firewalls,
Routers, Switches, Wifi APs.

Malfunctioning devices or equipment are a common network problem that can disrupt
network operations and lead to various connectivity issues. This category
encompasses hardware failures or malfunctions within network devices, such as
routers, switches, firewalls, servers, or network interface cards (NICs). When devices
malfunction, they may experience performance degradation or cease to function
altogether, impacting the overall network performance and user experience.

You need to ensure that all the devices on your network are configured correctly in
order for your network to work properly. Whenever you install or reconfigure a device,
or upgrade equipment firmware on your network, you need to test that device to
ensure that it’s been configured correctly.

Many network performance issues are caused by device misconfigurations that can
affect different parts of your network and turn into major problems down the line.
That’s why you need to pay attention to all the switches and devices on your network
to ensure that they’re always working as they should be, and react quickly if they
aren’t.

I. The Consequences of Malfunctioning Devices or Equipment

Network Downtime: When crucial network devices fail, it can result in network outages
and disrupt communication and data transfer.
Slow Performance: Malfunctioning devices may struggle to process network traffic
efficiently, leading to slow data transfer and increased latency.

Data Loss: Hardware failures can cause data loss, especially if the malfunctioning
device is responsible for data storage or backups.

Reduced Reliability: Frequent device malfunctions erode the network's reliability,

causing frustration for users and hindering business operations.

II. The Causes of Malfunctioning Devices or Equipment

Hardware Failure: Components within network devices can fail due to wear and tear,
manufacturing defects, or age. Common hardware failures include power supply
issues, memory failures, or fan malfunctions.

Overheating: Network devices that are not adequately cooled or positioned in poorly
ventilated areas can overheat, leading to malfunctions and performance degradation.

Software Bugs: Firmware or software bugs within network devices can cause erratic
behavior or crashes, impacting their ability to function correctly.

Power Surges or Electrical Issues: Power surges or electrical problems can damage
network devices and render them inoperable.

Environmental Factors: Adverse environmental conditions, such as exposure to

moisture, dust, or extreme temperatures, can contribute to device malfunction.

III. How to Identify & Troubleshoot Malfunctioning Devices or Equipment

Network Device Monitoring: Use network monitoring tools like Obkio to track device
performance metrics, such as CPU usage, memory utilization, and temperature
readings. Abnormal values may indicate potential device malfunctions. Obkio’s
network device monitoring solution is a simple and easy solution that offers advanced
polling for SNMP Monitoring for all SNMP-enabled devices along your network to
ensure they’re all performing as they should be.

Device Logs: Review device logs and error messages to identify any hardware or
software-related issues reported by the device.

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Hardware Diagnostics: Many network devices come with built-in diagnostic tools that
can identify hardware failures or malfunctions.

Hardware Replacement: If a device is suspected to be malfunctioning, consider

replacing it with a known-working spare or a new device to confirm if the issue is
resolved.

Firmware/Software Updates: Ensure that devices have the latest firmware and
software updates to fix known bugs and optimize performance.

Temperature Management: Check the environmental conditions of network devices

and ensure they are adequately cooled and placed in suitable locations.

Power Protection: Implement surge protectors and uninterruptible power supply

(UPS) systems to safeguard devices against electrical issues.

By proactively identifying and addressing malfunctioning devices or equipment,

businesses can reduce network downtime, maintain reliable operations, and ensure
an efficient and responsive network infrastructure.

How to Identify Network Problems & Diagnose Network Issues

How to Identify Network Problems & Diagnose Network Issues

Learn how to identify network issues by looking at common problems, causes,

consequences and solutions.

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IV. Network Troubleshooting Scenarios for Malfunctioning Devices or Equipment

When dealing with malfunctioning network devices or equipment, prompt

troubleshooting is essential to identify and resolve the issues efficiently. Here are
some network troubleshooting scenarios to consider when facing malfunctioning
devices or equipment:

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Device Power Status: Check if the malfunctioning device is powered on and receiving
adequate power. Verify power connections and consider testing the device with a
different power source or power cable.

Device Reset or Reboot: Perform a controlled restart or reboot of the malfunctioning

device. Sometimes, a simple restart can resolve temporary issues.

Check Device Status Lights: Observe the status lights or LEDs on the malfunctioning
device to identify any error codes or abnormal behavior. Refer to the device's
documentation for guidance.

Verify Firmware/Software Versions: Ensure that the device's firmware or software is

up to date. If available, apply the latest firmware updates or patches from the
manufacturer's website.

Inspect Device Logs: Review the device logs to identify any error messages or alerts
that might indicate the cause of the malfunction.

Device Configuration: Verify the device configuration to ensure it aligns with the
network's requirements and network monitoring best practices. Look for
misconfigurations or conflicting settings.

Isolate Device from the Network: Temporarily disconnect the malfunctioning device
from the network to determine if it is the cause of broader network issues.

Test Connectivity and Cable: Check the connectivity of the malfunctioning device by
testing it with a known-working cable and connecting it to a different network port.

Temperature and Ventilation: Overheating can cause devices to malfunction. Ensure

that the device has adequate ventilation and is not exposed to excessive heat.

Test with Different Ports: If the device has multiple ports, test with different ports to
check for faulty hardware on specific interfaces.

Check for Hardware Faults: Examine the device's physical components for any signs
of damage or hardware faults.

Reinstall or Reset Device: If appropriate, consider reinstalling or performing a factory

reset on the malfunctioning device to rule out software-related issues.

Device Interoperability: Verify if the malfunctioning device is compatible with other

devices on the network. Ensure that it supports required protocols and standards.
Replace or Repair Faulty Components: If hardware components are found to be
faulty, consider replacing or repairing them.

Check for Environmental Factors: Determine if the malfunction could be caused by

environmental factors such as electromagnetic interference or power fluctuations.

Update Drivers: For network interface cards and other peripheral devices, update
drivers to the latest versions to address potential compatibility issues.

Verify Network Connectivity: Confirm that the malfunctioning device is connected to

the correct network and VLAN (if applicable).

Seek Vendor Support: If the issue persists or is beyond your troubleshooting

capabilities, contact the vendor's technical support for further assistance.

Always document the troubleshooting steps and any changes made to the device or
network during the process. Thorough documentation helps in future reference and
sharing information with others who might be assisting with the troubleshooting
process.

Network Problem #6. DNS Issues

DNS or Domain Name System, controls how visitors find your website over the
Internet.

It is essentially a directory for the Internet (and every Internet-connected device) that
matches domain names with IP addresses. Every single website has its own IP
address on the web, and computers can connect to other computers via the Internet
and look up websites using their IP address. When you type in a domain name in your
Internet browser, DNS works to find the information connected to that domain.

DNS issues are very common network problems that many people tend to overlook.
DNS issues occur when you are unable to connect to an IP address, signalling that
you may have lost network or Internet access. For example, your site can
simultaneously appear online for you, but looks to be offline to your visitor
When DNS issues arise, users may experience difficulties accessing websites,
sending emails, or connecting to network resources.

I. The Consequences of DNS Issues

The inability to access the Internet or particular sites can have a very immediate and
negative impact on your business - especially if it means that users cannot access
your site. Just a few hours offline can cost your company in more ways than one,
which is why it’s important to find and fix DNS problems as soon as possible.

Website Inaccessibility: Users may be unable to access websites or services due to

failed DNS resolutions.

Email Delivery Issues: DNS problems can affect email delivery, causing delays or
preventing emails from being sent or received.

Slow Internet Browsing: DNS lookup delays can result in sluggish website loading
times and overall slow internet browsing experiences.

Security Risks: DNS hijacking or cache poisoning can lead to security vulnerabilities,
exposing users to phishing attacks or other malicious activities

II. The Causes of DNS Issues

Bad Configurations: You may experience issues due to improper configuration of

DNS records.

High DNS Latency: High Latency, which is the measure of time it takes for data to
reach its destination across a network, can cause slow and abnormally long loading
times.

High TTL Values: High “time to live” values on your records, will lead to high
propagation wait times. Traceroute tools, like Obkio’s Live Traceroutes feature and
Obkio Vision Visual Traceroue tool, actually track and monitor TTL values.
Hardware/Network Failures: DNS problems can be caused by hardware failures on
the host machine or network failures. Troubleshoot network/ hardware configuration
settings using a network performance monitoring tool to identify the source of the
problem.

DNS Server Outages: If the DNS server responsible for resolving domain names
becomes unavailable or experiences downtime, users will be unable to access
websites or services.

Misconfigured DNS Settings: Incorrectly configured DNS settings on network devices

or client systems can lead to failed DNS lookups.

DNS Cache Poisoning: Malicious actors can compromise DNS caches, leading to
incorrect or spoofed DNS records being served, redirecting users to malicious
websites.

Network Connectivity Issues: Internet connectivity issues or problems or routing can

prevent DNS queries from reaching DNS servers or receiving responses and lead to
network connectivity issues

DNS Propagation Delays: After making changes to DNS records, it can take time for
the changes to propagate across the internet. During this period, users may
experience inconsistent DNS resolution.

DNS Hijacking: Cyber attackers may hijack DNS queries to redirect users to
fraudulent websites or phishing pages.

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III. How to Identify & Troubleshoot DNS Issues

DNS Monitoring: Utilize network monitoring tools like Obkio to track DNS queries and
response times. Monitor DNS servers' performance and ensure they are resolving
queries promptly.

DNS Testing Tools: Use DNS testing tools to check the network response time and
accuracy of DNS queries from different locations.

Flush DNS Cache: On client systems, flush the DNS cache to clear any outdated or
corrupted entries that may be causing issues.

99
Check DNS Server Status: Verify the status of DNS servers to ensure they are
operational and responsive.

Review DNS Settings: Check DNS settings on network devices, routers, and client
systems for any misconfigurations.

DNSSEC Implementation: Consider implementing DNSSEC (DNS Security

Extensions) to prevent DNS cache poisoning and improve DNS security.

Monitor DNS Logs: Review DNS server logs for any unusual activities or error
messages that may indicate issues.

Update DNS Records: Ensure that DNS records are correctly updated and
propagated across authoritative DNS servers.

By proactively identifying and resolving DNS issues, businesses can ensure smooth
and reliable access to online resources, improve internet browsing experiences, and
enhance overall network security.

How to Troubleshoot Intermittent Internet Connection: Don't Get Caught in the

Spinning Wheel of Death

How to Troubleshoot Intermittent Internet Connection

Learn how to troubleshoot intermittent Internet connection issues with Network

Monitoring. Find & fix the cause of intermittent Internet issues.

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IV. Network Troubleshooting Scenarios for DNS Issues

DNS (Domain Name System) issues can cause various network problems, including
the inability to access websites, email services, or other network resources. Here are
some network troubleshooting scenarios to consider when dealing with DNS issues:

100
Ping and Traceroute: Use the ping and traceroute commands to verify DNS
resolution. If you can ping IP addresses but not domain names, it indicates a DNS
resolution problem.

Check DNS Server Settings: Verify that the DNS server settings on the client devices
are correct. Ensure that they are pointing to the appropriate DNS servers, such as
those provided by the ISP or internal DNS servers.

DNS Server Reachability: Check if the DNS servers are reachable from the client
devices. Use ping to confirm if the DNS servers respond to requests.

Flush DNS Cache: Clear the DNS cache on the client devices to ensure they fetch
fresh DNS records from the DNS servers.

DNS Server Logs: Analyze the DNS server logs for errors or issues. Look for failed
DNS requests or unusual patterns.

DNS Forwarding and Recursion: Ensure that DNS servers are properly configured for
forwarding and recursion. Misconfigured forwarding can lead to failed DNS resolution.

DNSSEC Validation: If DNSSEC (Domain Name System Security Extensions) is

enabled, check for DNSSEC validation issues that might prevent resolution for some
domains.

Check DNS Records: Verify the DNS records for the domain in question (A, CNAME,
MX, etc.) to ensure they are correctly configured.

Firewall and Filtering: Review firewall rules and content filtering settings that might
block DNS traffic or DNS resolution.

ISP DNS Issues: Contact the Internet Service Provider (ISP) to check if there are any
DNS issues or outages in their DNS infrastructure.

DNS Load Balancing: If using DNS-based load balancing, ensure that it is working
correctly and directing traffic to the appropriate servers.

DNS Round Robin: If DNS round-robin is used, verify that all the IP addresses in the
DNS response are functional.

Reverse DNS Lookup: Check reverse DNS lookup (PTR) records to ensure they
match the corresponding forward (A) records.
DNS Timeouts: Monitor for DNS timeouts in application logs or network captures,
which may indicate DNS server unresponsiveness.

DNS Hijacking or Spoofing: Investigate for any signs of DNS hijacking or spoofing,
which could redirect users to malicious websites.

DNS Over HTTPS (DoH) or DNS Over TLS (DoT): If DoH or DoT is implemented,
verify the configuration and connectivity to the chosen secure DNS resolver.

IPv6 DNS Configuration: Ensure that DNS resolution works correctly for both IPv4
and IPv6 addresses.

Third-Party DNS Services: If using third-party DNS services, verify their service status
and reachability.

DNS Health Check Tools: Utilize DNS health check tools or online DNS diagnostics to
assess DNS configuration and performance.

By systematically troubleshooting DNS issues, you can identify and resolve the root
cause of the problem, ensuring smooth DNS resolution and proper network
connectivity. If the issue persists or is beyond your expertise, don't hesitate to seek
assistance from qualified network administrators or DNS experts.

Network Problem #7. Interference in the Wireless Network

WiFi problems are one of the most common complaints surrounding modern day
connectivity.

Interference in the wireless network is a common and frustrating network problem that
can significantly impact Wi-Fi performance and reliability. Wireless networks, such as
Wi-Fi, rely on radio frequencies to transmit data between devices. Interference occurs
when other devices or signals disrupt this communication, leading to slow or
unreliable wireless connections.

Several factors contribute to wireless interference, and identifying and mitigating

these issues is crucial for maintaining a stable wireless network.
Signs of wireless interference include:

Low signal strength even when close to a WiFi broadcast device

Slower Internet connection when using connected over WiFi

Slow file transfers between computers over WiFi

Inability to pair WiFi or Bluetooth devices even when in proximity to the receiver

Intermittently dropping of WiFi connection

I. The Consequences of Interference in the Wireless Network

Slow Data Transfer: Interference can lead to a variety of Internet problems like slow
data transfer rates and reduced Internet speeds, affecting productivity and user
experience.

Connection Drops: Wireless interference can cause frequent disconnections or

dropped connections, disrupting ongoing tasks and communication.

Unreliable Connectivity: Users may experience intermittent connectivity issues,

making it challenging to access network resources consistently.

Reduced Coverage: Interference can result in reduced Wi-Fi coverage, creating dead
spots where wireless signals are weak or nonexistent.

II. The Causes of Interference in the Wireless Network

Very common household items, like microwave ovens or cordless phones, can slow
down your home Wi-Fi network performance. If you live in a densely populated area,
your neighbors’ Wi-Fi networks could actually be interfering with your own. This is
particularly true if you’re using a 2.4GHz wireless router.

102
Seeing as a failure can occur at any time, the first challenge for network
administrators is to quickly identify what can cause interference as well as the precise
time they occurred.

Overlapping Wi-Fi Channels: In environments with multiple Wi-Fi networks,

overlapping channels can lead to interference as signals interfere with each other.

Physical Obstructions: Physical obstacles like walls, floors, and large objects can
attenuate Wi-Fi signals, reducing signal strength and causing interference.

Electronic Devices: Other electronic devices operating on similar frequencies, such as

cordless phones, Bluetooth devices, and microwaves, can cause interference.

Nearby Access Points: When multiple access points are in close proximity, they can
interfere with each other's signals, especially if they are on the same or overlapping
channels.

Signal Reflection and Refraction: Wi-Fi signals can reflect off surfaces or refract
through materials, creating signal interference and dead zones.

III. How to Identify and Troubleshoot Interference in the Wireless Network

While users are usually quick enough to report problems, it’s ideal to identify and
solve the problem before it affects users.

Real-Time Network Monitoring: Utilize network monitoring tool, like Obkio for real-time
network monitoring to track Wi-Fi performance in real-time and detect sudden drops
in signal strength or connectivity issues that may indicate interference.

Wi-Fi Site Surveys: Conduct site surveys using Wi-Fi analysis tools within the network
monitoring platform to identify signal strength, coverage areas, and potential
interference sources.

Channel Analysis: Utilize network monitoring tools to analyze Wi-Fi channel utilization
and identify crowded or overlapping channels that may be contributing to interference.

Signal Strength Testing: Measure Wi-Fi signal strength across different areas of the
workspace using network monitoring tools to identify weak or strong signal zones.
Device Interference Check: Identify and isolate devices or equipment that may be
causing wireless interference, using network monitoring to detect their presence and
impact on Wi-Fi performance.

Automated Alerts: Set up automated network monitoring alerts within the network
monitoring tool to be notified immediately when Wi-Fi interference is detected,
allowing for quick investigation and resolution.

Historical Analysis: Utilize historical data provided by the network monitoring platform
to identify patterns of interference and assess the effectiveness of previous
troubleshooting efforts.

Network Topology Mapping: Use network monitoring tools or network observability

tools to create visual representations of the network topology, helping identify
potential physical obstructions or sources of interference.

By leveraging network monitoring alongside these troubleshooting approaches,

businesses can proactively identify and address wireless interference, ensuring a
more reliable and efficient Wi-Fi network. Network monitoring provides real-time
insights, historical data, and automated alerts, empowering IT teams to promptly
resolve interference issues and optimize wireless performance for enhanced user
satisfaction.

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IV. Network Troubleshooting Scenarios for Interference in the Wireless Network

Interference in a wireless network can cause signal degradation, reduced throughput,

and disconnections. Troubleshooting wireless interference requires careful analysis
and mitigation strategies. Here are some network troubleshooting scenarios to
consider when dealing with interference in a wireless network:

Physical Obstructions: Identify and remove or reposition physical obstructions such as

walls, furniture, metal objects, or large appliances that may block or attenuate the Wi-
Fi signal.

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Neighboring Wi-Fi Networks: Use a Wi-Fi analyzer tool to identify nearby Wi-Fi
networks and the channels they are operating on. Choose a less congested channel
for your wireless network to reduce interference.

Microwave Ovens and Cordless Phones: Microwave ovens and some cordless
phones operate in the same frequency range as Wi-Fi networks (2.4 GHz). Keep Wi-
Fi access points away from these devices to minimize interference.

Bluetooth Devices: Bluetooth devices can cause interference with Wi-Fi networks,
especially in the 2.4 GHz frequency band. Separate Bluetooth devices from Wi-Fi
access points or use Wi-Fi channels that are far from Bluetooth frequencies.

Electronic Devices: Identify and relocate electronic devices that emit electromagnetic
interference (EMI) or radio-frequency interference (RFI), such as baby monitors,
wireless cameras, or wireless speakers.

Dual-Band Wi-Fi Devices: If possible, use dual-band Wi-Fi devices that can operate in
both 2.4 GHz and 5 GHz frequency bands. The 5 GHz band is typically less
congested and offers better performance.

Wi-Fi Signal Strength: Check the Wi-Fi signal strength at different locations within the
coverage area to identify areas with weak signals that might be susceptible to
interference.

Wi-Fi Access Point Placement: Optimize the placement of Wi-Fi access points to
achieve better coverage and reduce dead zones. Consider using Wi-Fi range
extenders or mesh systems for larger areas.

Wi-Fi Signal Overlapping: Avoid overlapping Wi-Fi signal coverage from multiple
access points, as it can lead to interference. Adjust access point transmit power or
channel settings to minimize overlap.

Rogue Wi-Fi Devices: Look for rogue Wi-Fi access points or devices that might be
interfering with your network. Use wireless intrusion detection systems (WIDS) to
identify unauthorized devices.

DFS Channels (5 GHz): In the 5 GHz band, some channels require Dynamic
Frequency Selection (DFS) due to radar detection requirements. Ensure your devices
support DFS and are using appropriate DFS channels.

WLAN Optimization: Use Wi-Fi optimization techniques such as band steering and
airtime fairness to balance client connections and reduce interference.

105
Wireless Site Survey: Perform a wireless site survey to assess the overall wireless
environment and identify potential sources of interference.

Quality of Service (QoS): Implement QoS policies to prioritize critical Wi-Fi traffic and
minimize the impact of non-essential traffic on network performance.

Regular Monitoring: Continuously monitor Wi-Fi performance, interference levels, and

client connectivity to detect and address issues proactively.

Firmware Updates: Keep Wi-Fi access points and wireless devices' firmware up to
date to take advantage of performance improvements and bug fixes.

By systematically troubleshooting wireless interference, you can optimize your Wi-Fi

network's performance and deliver a more reliable wireless experience to users. Use
appropriate network monitoring and diagnostic tools, like we mentioned in the section
above, to analyze Wi-Fi performance and make informed decisions during the
troubleshooting process.

Network Problem #8. Network Congestion

Network congestion is a prevalent network problem that occurs when there is an

excessive amount of data traffic on the network, leading to congestion or
bottlenecking. It can happen at various points in the network, such as routers,
switches, or network links, where the capacity to handle data becomes overwhelmed
by the volume of incoming traffic.

Network congestion can result from increased data demands, inefficient network
configurations, or inadequate bandwidth allocation, and it can significantly impact the
overall network performance and user experience.

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Packet Loss - Common Network Problems
I. The Consequences of Network Congestion

Network congestion can have severe ramifications on network performance and user
experience. Let's go over the impact of congestion, including:

Slow Data Transfer: Network congestion can result in slower data transfer rates,
leading to delays in accessing resources and data.

Latency and Packet Loss: Congestion can cause increased latency (delays) and
packet loss, affecting real-time applications such as video conferencing or online
gaming.

Dropped Connections: Congestion can cause connections to drop or time out,

resulting in failed file transfers or disrupted communication.

Reduced Productivity: Sluggish network performance can hinder productivity, as

users may experience delays in performing critical tasks.

User Frustration: Network congestion can lead to frustration among users due to the
inability to access resources or slow response times.

II. The Causes of Network Congestion

Understanding the root causes of network congestion is vital for devising appropriate
solutions. Let’s go over the most common causes of network congestion in more
detail:

Increased Data Traffic: As the number of connected devices and users on the
network grows, the demand for data transfer increases, leading to congestion.

Bandwidth Limitations: Insufficient available bandwidth can cause congestion,

especially in networks with limited capacity or where data-intensive applications
dominate.

108
Network Misconfigurations: Inefficient network configurations, such as incorrect
Quality of Service (QoS) settings or improper routing, can lead to inefficient data flow
and congestion.

DDoS Attacks: Distributed Denial of Service (DDoS) attacks involve overwhelming a

network with an enormous amount of traffic, causing congestion and rendering
services unavailable.

Software and Firmware Bugs: Network devices with software or firmware bugs can
behave unpredictably, potentially contributing to network congestion.

III. How to Identify and Address Network Congestion

To mitigate network congestion, early detection and appropriate measures are

essential.

Network Monitoring: Use network monitoring tools like Obkio to track network
performance metrics, including bandwidth utilization and traffic patterns. Identify
periods of high traffic and potential congestion.

Traffic Analysis: Analyze the type of data traffic and its volume to identify bandwidth-
intensive applications or devices causing congestion.

Quality of Service (QoS) Implementation: Implement QoS policies to prioritize critical

applications and services over less essential ones during periods of congestion.

Bandwidth Upgrades: Consider upgrading network bandwidth to accommodate

increasing data demands and alleviate congestion.

Load Balancing: Utilize network load balancing techniques to distribute network traffic
across multiple routes or devices, preventing bottlenecks in specific areas.

Traffic Shaping: Implement traffic shaping to control the flow of data, ensuring fair
distribution of bandwidth among different applications or users.

Network Optimization: Regularly review network configurations and performance to

identify areas for network optimization and improvement.

By proactively identifying and addressing network congestion, businesses can ensure

a smoother and more responsive network, enhancing productivity and user
satisfaction. Network congestion management plays a crucial role in maintaining a
reliable and efficient network infrastructure that meets the growing demands of
modern businesses.

How to Detect Network Congestion Like A Pro: Don't Get Jammed Up

How to Detect Network Congestion Like A Pro

Learn how to detect network congestion & perform a network congestion test inside &
outside your network with Network Monitoring & Network Device Monitoring.

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IV. Network Troubleshooting Scenarios for Network Congestion

Network congestion occurs when the network experiences high levels of traffic,
causing slow data transmission, increased latency, and potential service disruptions.
Here are some network troubleshooting scenarios to consider when dealing with
network congestion:

Identify Peak Usage Hours: Monitor network traffic to identify peak usage hours when
congestion is most likely to occur. Plan for additional resources during these periods.

Bandwidth Monitoring: Use network monitoring tools with SNMP Network Monitoring
to track bandwidth usage and identify which applications or devices are consuming
the most bandwidth.

Quality of Service (QoS): Implement QoS policies to prioritize critical traffic, such as
VoIP or video conferencing, over non-essential traffic during periods of congestion.
Qos for VoIP is essential for mitigation congestion.

Malware or Botnet Activity: Malware-infected devices or botnet activity can cause

excessive traffic and contribute to network congestion. Use security tools to detect
and isolate infected devices.

111
Cloud Services and Backups: Cloud services and data backups can consume
significant bandwidth. Schedule backups during off-peak hours to avoid congestion.

Check Network Switches and Routers: Check network devices for errors or signs of
packet drops. Upgrade hardware if required to handle increased traffic.

Analyze Network Topology: Review the network topology to identify potential

bottlenecks or areas of contention.

Segment Network Traffic: Separate different types of traffic, such as voice, data, and
video, into separate VLANs to reduce contention.

Update Firmware and Drivers: Keep network devices' firmware and drivers up to date
to ensure optimal performance.

Optimize Protocols: Fine-tune network protocols to reduce overhead and improve

efficiency.

Load Balancing: Distribute traffic across multiple links or paths using load balancing
techniques.

Consider Network Upgrades: If congestion is chronic and impacting productivity,

consider upgrading network infrastructure, such as increasing bandwidth or using
faster network technologies.

Monitor Network Flow: Use flow analysis tools to understand traffic patterns and
identify potential sources of congestion.

Implement Caching: Use caching solutions for frequently accessed content to reduce
the need for repetitive data transfers.

Throttle Bandwidth-Intensive Applications: Limit the bandwidth usage of certain

applications or devices that are causing congestion.

Review ISP Performance: If the congestion is beyond your local network, contact your
Internet Service Provider (ISP) to assess the overall network performance.

Peer-to-Peer (P2P) Traffic Control: Implement policies to control and prioritize P2P
traffic, which can consume a significant amount of bandwidth.

Educate Users: Educate users about responsible internet usage and the impact of
excessive data consumption on network performance.

112
By thoroughly troubleshooting network congestion, you can identify the root causes
and implement appropriate solutions to improve overall network performance and
user experience. Regular monitoring and analysis of network traffic patterns will help
you proactively address congestion issues before they become significant problems.

Network Problem #9. Packet Loss

Packet loss is a prevalent network problem characterized by the failure of data

packets to reach their intended destination within a network. It occurs when one or
more packets of data are lost or discarded during transmission, leading to incomplete
or corrupted data delivery.

Packet loss can happen due to various factors, such as network congestion,
hardware issues, or data transmission errors, and it can significantly impact network
performance and user experience.

Packet Loss - Common Network Problems

113
In the same family of network issues, you may also encounter:

Packet Reordering: When network packets arrive at their destination out of sequence

Packet Duplication: The unintended replication of data packets during transmission.

When packets are duplicated, multiple identical copies of the same packet are
delivered to the destination.

I. The Consequences of Packet Loss

Data Corruption: Packet loss can lead to incomplete or corrupted data transmissions,
affecting the accuracy and integrity of transmitted information.

Slow Data Transfer: Retransmitting lost packets can slow down data transfer rates,
leading to increased latency.

Degraded Voice and Video Quality: In real-time communication applications like VoIP
and video conferencing, packet loss can result in choppy audio or pixelated video.

Reduced Throughput: The loss of packets in data streams can reduce the overall
throughput and efficiency of data delivery.

Impact on Applications: Packet loss can negatively affect the performance of

applications, leading to slower response times and disrupted services.

II. The Causes of Packet Loss

Network Congestion: High levels of data traffic or network congestion can result in
packets being dropped to alleviate the strain on the network.

Network Jitter: Variations in packet delay, known as jitter, can lead to packet loss
when packets arrive out of order or too late to be processed.

Buffer Overflow: When network devices' buffers become overwhelmed due to high
data rates, excess packets can be discarded.

Data Transmission Errors: Errors during data transmission can cause packets to be
corrupted or lost, especially in unreliable transmission mediums.
Wireless Interference: Interference from other wireless signals or physical obstacles
can lead to packet loss in Wi-Fi networks.

Network Hardware Issues: Faulty network switches, routers, or other hardware can
cause packet loss as packets fail to traverse the network correctly.

III. How to Identify & Troubleshoot Packet Loss

Network Monitoring: Utilize network monitoring tools like Obkio to measure packet
loss and track packet loss rates and identify periods of increased packet loss.

Packet Analysis: Conduct packet analysis to identify the root causes of packet loss
and determine the affected network segments.

Bandwidth Optimization: Optimize bandwidth allocation and implement Quality of

Service (QoS) to prioritize critical traffic and reduce packet loss.

Jitter Control: Minimize network jitter through QoS and traffic shaping to prevent
packet loss due to variations in packet delay.

Network Hardware Inspection: Inspect network hardware to identify and replace faulty
devices contributing to packet loss.

Wireless Signal Optimization: Optimize Wi-Fi signals to reduce wireless interference

and decrease packet loss in wireless networks.

By proactively identifying and addressing packet loss, businesses can improve

network performance, maintain data integrity, and enhance the overall user
experience. Network monitoring, packet analysis, and appropriate network
optimization techniques play a vital role in detecting and mitigating packet loss issues
effectively.

How to Measure Packet Loss & Detect Packet Loss Issues

How to Measure Packet Loss & Detect Packet Loss Issues

How to measure packet loss with Obkio’s Network & Packet Loss Monitoring tool.
Check for packet loss in your network & read packet loss measurements.

115
Learn more right arrow

IV. Network Troubleshooting Scenarios for Packet Loss

Packet loss can degrade network performance and cause disruptions in data
transmission. Troubleshooting packet loss requires identifying the underlying causes
and implementing appropriate solutions. Here are some network troubleshooting
scenarios to consider when dealing with packet loss:

Ping and Traceroute: Use ping and traceroute commands to identify packet loss and
latency issues between devices. This can help pinpoint the location and severity of
packet loss.

Check Network Cables: Inspect network cables and connectors for damage, loose
connections, or faulty wiring that could lead to packet loss.

Verify Network Interface Cards (NICs): Test and update network interface card drivers
to ensure they are functioning correctly.

Physical Layer Troubleshooting: Examine physical network components, such as

switches and routers, for signs of hardware issues or congestion.

Bandwidth Saturation: Monitor network traffic to see if bandwidth saturation is causing

packet loss. Consider implementing Quality of Service (QoS) policies to prioritize
critical traffic.

Check for Network Congestion: Analyze network traffic patterns to identify areas of
congestion that may be causing packet loss.

Wireless Interference: In wireless networks, interference from neighboring Wi-Fi

networks or other devices can lead to packet loss. Use a Wi-Fi analyzer to identify
potential sources of interference.

Reduce MTU Size: If you are experiencing fragmentation-related packet loss, reduce
the Maximum Transmission Unit (MTU) size to prevent fragmentation.

Jitter and Buffering: Examine network devices for excessive jitter or inadequate
buffering that can contribute to packet loss.
Routing Issues: Verify routing configurations to ensure packets are being routed
correctly without any loops or misconfigurations.

Firewall Settings: Check firewall rules to ensure they are not blocking legitimate traffic
and causing packet loss.

Malware and DDoS Attacks: Monitor for signs of malware infections or Distributed
Denial of Service (DDoS) attacks, as they can cause packet loss.

ISP Issues: If the packet loss is beyond your local network, contact your Internet
Service Provider (ISP) to investigate potential problems with their network.

Buffer Bloat: Address buffer bloat issues by configuring QoS and traffic shaping to
manage buffer size and prevent excessive queuing delay.

Ping Flood or DDoS Testing: If you suspect malicious activities, investigate for
possible ping flood or DDoS testing targeting your network.

Update Firmware and Software: Keep network devices' firmware and software up to
date to prevent known issues causing packet loss.

Trunk Port Errors: For VLANs and trunk ports, check for misconfigurations or errors
that might cause packet loss.

Segment and Isolate Network Traffic: Use VLANs and subnetting to isolate different
types of network traffic and prevent congestion-related packet loss.

By methodically troubleshooting packet loss, you can identify the root causes and
apply appropriate solutions to improve network performance and reliability.

Network Problem #10. Jitter

Jitter is a common network problem that refers to the variation in packet delay
experienced during data transmission over a network. It occurs when data packets
encounter fluctuations in the time it takes to traverse the network from the source to
the destination.

116
Jitter is particularly relevant in real-time communication applications, such as Voice
over Internet Protocol (VoIP) calls and video conferencing, where timing precision is
crucial for smooth and seamless communication.

Jitter - Common Network Problems

I. The Consequences of Jitter

Voice and Video Quality Issues: In real-time communication applications like VoIP
and video conferencing, excessive jitter can cause choppy audio or video, affecting
the overall call quality.

Delayed Data Transmission: Jitter can lead to variations in data transmission delays,
impacting the responsiveness of applications and services.

Synchronization Problems: For time-sensitive applications, jitter can cause

synchronization issues between data packets, leading to data corruption or loss.

Interference with Real-Time Applications: Jitter can disrupt the flow of real-time data,
making it challenging to maintain a smooth user experience.

II. The Causes of Jitter

Network Congestion: High levels of data traffic or network congestion can lead to
varying packet queuing times and result in jitter.
Packet Routing: Different paths and routing delays taken by packets can cause
varying arrival times at the destination.

Network Jitter: Variations in network jitter itself can compound the issue, leading to
additional packet timing discrepancies.

Network Interference: Physical obstacles, wireless interference, or other external

factors can introduce varying transmission delays.

Buffering: Buffering in network devices can introduce variations in packet arrival times
due to the varying lengths of packets.

III. How to Identify & Troubleshoot Jitter

Network Monitoring: Use network monitoring tools like Obkio to measure jitter levels
and identify periods of increased jitter. Obbkio will also help you identify the cause,
source and time of jitter spikes in you network so you where where and how to direct
your troubleshooting efforts.

Quality of Service (QoS) Implementation: Implement QoS policies to prioritize real-

time traffic, reducing the impact of jitter on critical applications.

Buffer Management: Optimize buffer settings in network devices to minimize the

effects of buffering-induced jitter.

Traffic Shaping: Use traffic shaping techniques to regulate the flow of data and
manage jitter more effectively.

Path Optimization: Optimize network paths to minimize variations in packet routing

and reduce jitter.

Wireless Signal Optimization: In wireless networks, optimize Wi-Fi signals to reduce

interference and decrease jitter.

By proactively identifying and addressing jitter, businesses can improve the

performance of real-time communication applications, ensuring smooth voice and
video calls, and enhancing the overall user experience. Network monitoring, QoS
implementation, and network optimization play a crucial role in detecting and
mitigating jitter effectively.

117
How to Measure Jitter & Keep Your Network Jitterbug Free

How to Measure Jitter & Keep Your Network Jitterbug Free

Learn how to measure network jitter using Obkio’s Network Monitoring software to
identify network problems & collect data to troubleshoot.

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IV. Network Troubleshooting Scenarios for Jitter

Jitter is the variation in the delay of packet delivery in a network, which can lead to
inconsistent and unpredictable performance. Troubleshooting jitter involves identifying
the causes of delay variations and implementing measures to mitigate its impact.
Here are some network troubleshooting scenarios to consider when dealing with jitter:

Ping and Traceroute: Use ping and traceroute commands to measure latency and
identify potential variations in packet delivery times.

Check Network Utilization: High network utilization can contribute to jitter. Monitor
network traffic to identify congestion points and take appropriate actions to alleviate it.

Quality of Service (QoS): Implement QoS policies to prioritize real-time traffic, such as
VoIP and video conferencing, over non-time-sensitive traffic to reduce jitter.

Buffer Bloat: Buffer bloat occurs when excessively large buffers cause delays in
packet delivery. Adjust buffer sizes on routers and switches to manage latency.

Packet Loss: Packet loss can exacerbate jitter. Address any packet loss issues, as it
may lead to increased jitter levels.

Wireless Interference: In wireless networks, interference from other devices or

neighboring networks can cause jitter. Use a Wi-Fi analyzer to identify sources of
interference.

Network Congestion: Congestion on the network can lead to increased jitter. Identify
and resolve congestion points to minimize its impact.

118
Physical Layer Issues: Inspect network cables and connectors for damage or faults
that may cause delays in packet delivery.

Network Switches and Routers: Verify the performance of network switches and
routers, as hardware issues can contribute to jitter.

Jitter Buffer: For real-time applications, such as VoIP, ensure that jitter buffer settings
are appropriately configured to compensate for jitter.

Traffic Shaping: Use traffic shaping techniques to control the flow of traffic and
prevent sudden bursts of data that may cause jitter.

Power Management: Disable power-saving features on network devices that may

introduce latency variations.

Proper Synchronization: Ensure that clocks are synchronized across network devices
to prevent timing discrepancies that contribute to jitter.

VoIP Codecs: For VoIP systems, consider using different codecs that are less
sensitive to network jitter.

Update Firmware and Software: Keep network devices' firmware and software up to
date to address known issues related to jitter.

ISP Performance: If jitter is beyond your local network, contact your Internet Service
Provider (ISP) to assess and address potential issues on their network.

Monitor Network Performance: Continuously monitor network performance to identify

patterns of jitter and take proactive measures to improve and check network stability.

Use Network Diagnostic Tools: Employ network diagnostic tools to analyze jitter
levels and identify sources of delay variations.

By systematically troubleshooting jitter, you can identify the underlying causes and
apply appropriate solutions to improve network performance and deliver a smoother
experience for real-time applications.

Network Problem #11. Routing Problems

119
Routing problems are a common network issue that occurs when data packets are
unable to reach their intended destination due to incorrect or inefficient routing
decisions. Routing is the process of determining the best path for data to travel from
the source to the destination across a network.

When routing problems arise, data packets may take suboptimal paths, experience
delays, or even get lost, leading to disruptions in network communication and
performance.

I. The Consequences of Routing Problems

Slow Data Transfer: Routing problems can lead to longer data transmission times,
causing delays in accessing resources and services.

Packet Loss: Incorrect routing decisions can cause packets to be lost or dropped
during transmission, affecting data integrity.

Network Inefficiency: Routing problems can lead to inefficient use of network

resources, increasing network latency and reducing overall performance.

Disruptions in Communication: Critical services and applications may become

unavailable or experience disruptions due to routing problems.

II. The Causes of Routing Problems

Misconfigurations: Incorrect configuration of routing protocols or routing tables can

lead to suboptimal or incorrect routing decisions.

Network Congestion: High levels of network congestion can cause routers to make
suboptimal routing choices, leading to delays and packet loss.

Link Failures: When a link between network devices fails, routers may need to reroute
traffic, and if this process is not seamless, routing problems can occur.

BGP (Border Gateway Protocol) Issues: In large-scale networks, BGP

misconfigurations or route flapping can cause routing problems and instability.
Inadequate Bandwidth: Insufficient bandwidth on certain links can cause congestion
and result in suboptimal routing decisions.

III. How to Identify & Troubleshoot Routing Problems

Network Monitoring: Use network monitoring tools like Obkio to track routing metrics
and identify anomalies or fluctuations in routing behavior.

Routing Protocol Analysis: Analyze the configuration of routing protocols and routing
tables to identify misconfigurations or inconsistencies.

Route Flap Damping: In BGP environments, enable route flap damping to mitigate the
impact of unstable routes.

Bandwidth Upgrades: Consider upgrading network links with inadequate bandwidth to

alleviate congestion and improve routing efficiency.

Link Redundancy: Implement link redundancy and dynamic routing protocols to

ensure seamless failover in case of link failures.

Regular Audits: Conduct regular audits of network configurations and routing tables to
identify and rectify potential issues.

By proactively identifying and addressing routing problems, businesses can maintain

a more efficient and reliable network infrastructure. Network monitoring, analysis of
routing protocols, and proper network configuration play a vital role in detecting and
resolving routing problems promptly. This ensures smooth and seamless data
transmission, optimizing network performance and user experience.

IV. Network Troubleshooting Scenarios for Routing Problems

Routing problems can lead to communication issues between network devices and
services. Troubleshooting routing problems requires careful analysis of the routing
configuration and associated network components. Here are some network
troubleshooting scenarios to consider when dealing with routing problems:

121
Ping and Traceroute: Use ping and traceroute commands to verify connectivity
between devices and identify potential routing issues.

Routing Table Verification: Check the routing tables on routers and switches to
ensure they are correctly configured and have the appropriate routes.

Routing Protocol Issues: If dynamic routing protocols are used, verify the protocol
configurations and adjacencies between neighboring routers.

Default Gateway: Confirm that devices have the correct default gateway configured,
which is critical for forwarding traffic to external networks.

Routing Loops: Check for routing loops in the network, which can cause packets to
circulate indefinitely. Correct any misconfigurations causing loops.

Routing Redistribution: If multiple routing protocols are in use, check for proper
redistribution to ensure that routes are distributed correctly.

Static Routes: Verify that any static routes are accurate and up-to-date, especially if
they are used to override dynamic routing protocols.

Routing Metrics: Review routing metrics to ensure they are set appropriately, as
improper metrics can lead to suboptimal routing decisions.

Routing Blackholes: Look for cases where routing paths unexpectedly drop packets
(routing blackholes) and investigate the cause.

Network Topology Changes: If recent network topology changes have occurred, verify
that routing configurations were updated accordingly.

Routing Protocol Authentication: Check if routing protocol authentication is enabled

and configured correctly to prevent unauthorized routing updates.

Split Horizon: For networks using split horizon, ensure that the split horizon rule is
properly applied to prevent routing information loops.

Routing Protocol Timers: Examine routing protocol timers to ensure they are set
appropriately for the network environment.

Network Segmentation: Confirm that network segmentation is accurate and logical,

and routes are correctly configured between segments.
Router Interface Status: Verify that router interfaces are operational and have the
correct IP addressing and subnet masks.

Physical Connectivity: Check for physical connectivity issues that may prevent proper
routing information exchange.

Backup Routes: If using backup or redundant routes, validate their configurations and
failover mechanisms.

Update Firmware and Software: Keep router and switch firmware/software up to date
to address known issues related to routing.

Monitor Routing Changes: Continuously monitor routing tables and log any changes
to quickly identify and address unexpected alterations.

By methodically troubleshooting routing problems, you can identify and resolve issues
that may be disrupting communication in the network. Regular network monitoring,
like we mentioned in the previous section, thorough analysis of routing configurations,
and prompt resolution of routing-related errors will help ensure smooth and reliable
network operation. If the issue persists or is beyond your expertise, seek assistance
from qualified network administrators or engage with vendor support.

Network Problem #12. VoIP Call Quality Issues

VoIP (Voice over Internet Protocol) call quality issues are a common network problem
that affects the clarity and reliability of voice communications over the Internet.

VoIP enables real-time voice communication using the internet as the transport
medium. However, various factors within the network environment can lead to
degraded call quality, causing disruptions, echoes, or delays in voice conversations.

123
VoIP Issues - Common Network Problems

I. The Consequences of VoIP Call Quality Issues

Poor Call Clarity: VoIP call quality issues can result in poor audio quality, making it
challenging to understand and communicate effectively.

Dropped Calls: Frequent call dropouts or disconnects due to packet loss or network
issues can hinder communication.

Communication Delays: High latency can lead to noticeable delays in conversations,

causing awkward pauses and communication difficulties.

Unreliable Communication: Call quality problems can lead to unreliable

communication experiences, affecting business operations and customer service.

II. The Causes of VoIP Call Quality Issues:

Network Congestion: High data traffic and network congestion can lead to delayed or
lost VoIP packets, resulting in poor call quality.
Jitter: Variations in packet delay, known as jitter, can cause voice packets to arrive
out of order, resulting in choppy or distorted audio during calls.

Packet Loss: Packet loss occurs when VoIP packets fail to reach their destination,
leading to gaps or dropouts in the conversation.

Latency: Latency, the delay between sending and receiving data, can lead to
noticeable delays and interruptions in VoIP calls.

Insufficient Bandwidth: Inadequate bandwidth can restrict the amount of data that can
be transmitted, leading to reduced call quality.

Network Interference: Interference from other devices or signals can impact VoIP
calls, especially in wireless environments.

How to Identify & Troubleshoot VoIP Call Quality Issues

Network Monitoring: Use network monitoring tools like Obkio to measure VoIP quality
metrics, such as MOS score, jitter, packet loss, and latency and identify issues
affecting VoIP Quality right on the VoIP Quality graph.

QoS Implementation: Implement Quality of Service (QoS)) policies to prioritize VoIP

traffic and minimize the impact of other data traffic on call quality.

Bandwidth Allocation: Ensure sufficient bandwidth is allocated to VoIP traffic to avoid

congestion and call quality issues.

Traffic Shaping: Utilize traffic shaping techniques to regulate data flow and prioritize
VoIP packets.

Jitter Buffer Optimization: Optimize jitter buffer settings to compensate for jitter and
ensure smoother audio playback.

Network Upgrades: Consider upgrading network infrastructure to handle increased

VoIP traffic and improve call quality.

By proactively identifying and addressing VoIP call quality issues, businesses can
ensure clear and reliable voice communication, improving collaboration and customer
interactions. Network monitoring, QoS implementation, and network optimization are
essential in detecting and mitigating VoIP call quality issues, enhancing overall
communication experiences within the organization.
How to Measure VoIP Quality & MOS Score (Mean Opinion Score)

How to Measure VoIP Quality & MOS Score (Mean Opinion Score)

Learn how to measure VoIP Quality using MOS Score (Mean Opinion Score) &
Obkio’s VoIP monitoring solution to identify poor VoIP Quality issues & dropped calls.

Learn more right arrow

IV. Network Troubleshooting Scenarios for VoIP Call Quality Issues

VoIP (Voice over Internet Protocol) call quality issues can negatively impact
communication and user experience. Troubleshooting VoIP call quality issues
requires identifying and resolving factors that affect voice transmission over the
network. Here are some network troubleshooting scenarios to consider when dealing
with VoIP call quality issues:

Check Bandwidth and Network Utilization: Insufficient bandwidth or high network

utilization can lead to call quality degradation. Monitor network traffic and ensure
sufficient bandwidth is available for VoIP traffic.

Quality of Service (QoS): Implement QoS policies to prioritize VoIP traffic over other
types of data to ensure smooth transmission and reduced latency.

Ping and Jitter: Measure ping and jitter between endpoints to identify potential latency
and jitter issues affecting call quality.

Packet Loss: Monitor for packet loss, which can significantly impact call quality.
Address any packet loss issues on the network.

Buffer Bloat: Buffer bloat can introduce latency in the network. Optimize buffer sizes
to prevent excessive delays in packet transmission.

Codecs: Check the codecs used for VoIP calls. Some codecs may prioritize
bandwidth savings over call quality. Consider using codecs that offer better voice
quality.
Network Congestion: Analyze network congestion points and address them to reduce
the impact on VoIP call quality.

Network Equipment: Verify the performance of network switches and routers, as

hardware issues can contribute to call quality problems.

Wireless Interference: In wireless networks, interference from neighboring Wi-Fi

networks or other devices can affect VoIP call quality. Use a Wi-Fi analyzer to identify
sources of interference.

Check for Dropped Packets: Identify and address any dropped packets affecting call
quality.

VoIP Gateway Configuration: Verify the configuration of VoIP gateways and devices
to ensure they are set correctly for the network environment.

Codec Mismatch: Ensure that both ends of the call are using compatible codecs. A
codec mismatch can lead to poor call quality.

Router Configuration: Review router configurations for issues that may affect VoIP
call quality, such as Access Control Lists (ACLs) or firewall settings.

Router Firmware Updates: Keep router firmware up to date to address known issues
related to VoIP call quality.

SIP Trunk and Provider Issues: If using SIP trunks or a VoIP service provider, check
for any issues with their service that may be affecting call quality.

Jitter Buffer Settings: Adjust jitter buffer settings to optimize the handling of packet
variations and reduce jitter-related issues.

Network Monitoring: Continuously monitor network performance to detect any

patterns of call quality degradation and identify the causes. Network monitoring tools
with VoIP monitoring, like Obkio, are especially important for identifying VoIP Quality
issues.

Network Latency: Address any latency issues in the network that may affect VoIP call
quality.

ISP Performance: If VoIP call quality issues persist, contact your Internet Service
Provider (ISP) to assess and address potential network problems.

By methodically troubleshooting VoIP call quality issues, you can identify and resolve
factors impacting call quality, leading to improved voice communication over the
network. Regular network monitoring and analysis will help you proactively detect and
address VoIP call quality issues as they arise.

Network Problem #13. Network Device Failures

Network device failures are a common and potentially disruptive network problem that
occurs when essential network devices, such as routers, switches, firewalls, or access
points, stop functioning correctly.

Network devices play a crucial role in data transmission, routing, and security within a
network infrastructure. When one of these devices fails, it can lead to service
disruptions, connectivity issues, and downtime.

Network Device Failures - Common Network Problems

I. The Consequences of Network Device Failures

128
Network Downtime: When critical network devices fail, it can lead to network
downtime and service interruptions.

Connectivity Issues: Failures in routers, switches, or access points can disrupt

network connectivity, affecting communication and data transfer.

Security Vulnerabilities: Failed security devices like firewalls can expose the network
to potential security breaches and unauthorized access. 8 Data Loss: Network device
failures can lead to data loss, especially if devices were responsible for data storage
or backup.

II. The Causes of Network Device Failures

Hardware Malfunctions: Network devices can experience hardware failures due to

wear and tear, overheating, power surges, or manufacturing defects.

Firmware or Software Errors: Faulty firmware or software updates can cause network
devices to behave unpredictably or fail.

Configuration Errors: Incorrect or misconfigured settings in network devices can lead

to malfunctions or instability.

Environmental Factors: Environmental conditions, such as exposure to extreme

temperatures, humidity, or dust, can impact the reliability of network devices.

III. How to Identify & Troubleshoot Network Device Failures

Network Monitoring: Use network monitoring tools like Obkio, along with Obkio’s
Network Device Monitoring feature to continuously monitor the health and
performance of core network devices to identify device availability, resource and
performance issues.

Device Health Checks: Perform regular health checks on network devices to identify
early signs of potential failures or abnormalities.

Firmware and Software Updates: Keep network device firmware and software up to
date with the latest stable releases to minimize potential issues.

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Configuration Backups: Regularly back up the configuration settings of network
devices to facilitate quick recovery in case of failures.

Redundancy and Failover: Implement redundancy and failover mechanisms to ensure

network continuity in the event of device failures.

Hardware Maintenance: Regularly inspect and maintain network devices to address

any physical issues and ensure proper functioning.

By proactively monitoring and maintaining network devices, businesses can reduce

the risk of network disruptions caused by device failures. Quick identification and
timely resolution of network device failures play a crucial role in minimizing downtime,
improving network reliability, and ensuring seamless communication and data
transfer.

Mastering the Art of Network Device Monitoring: A Beginner's Guide

Mastering the Art of Network Device Monitoring

Learn about Network Device Monitoring to easily monitor performance of firewalls,

routers & switches to identify problems like high CPU & bandwidth usage.

Learn more right arrow

IV. Network Troubleshooting Scenarios for Network Device Failures

Network device failures can disrupt network communication and lead to service
outages. Troubleshooting network device failures requires a systematic approach to
identify the failing device and address the issue promptly. Here are some network
troubleshooting scenarios to consider when dealing with network device failures:

Physical Inspection: Perform a physical inspection of the device to check for any
visible signs of damage, loose connections, or hardware failures.

Power Cycle: Power cycle the device by turning it off and then back on. Sometimes, a
simple reboot can resolve temporary issues.

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Check Power and Power Supply: Verify that the device is receiving power and that
the power supply is functioning correctly.

Check Device LEDs: Observe the status lights or LEDs on the device to identify any
error codes or abnormal behavior.

Device Logs: Analyze the device logs for error messages or alerts that might indicate
the cause of the failure.

Test Connectivity: Test connectivity to and from the device to see if it is responsive or
if it is completely unreachable.

Replace Network Cables: If applicable, try replacing the network cables connecting
the device to the network.

Isolate the Failing Device: If possible, isolate the failing device from the network to
prevent it from causing further disruptions.

Swapping Redundant Components: If the device has redundant components (e.g.,

power supplies, interface cards), try swapping them with spare parts to see if it
resolves the issue.

Verify Firmware/Software Versions: Ensure that the device's firmware or software is

up to date. Apply the latest firmware updates or patches from the manufacturer's
website.

Temperature and Ventilation: Overheating can cause devices to fail. Ensure that the
device has adequate ventilation and is not exposed to excessive heat.

Check for Environmental Factors: Determine if the device failure could be caused by
environmental factors such as power fluctuations or temperature variations.

Backup and Restore Configurations: If the device can be replaced, backup its
configuration and restore it on the replacement device to minimize downtime.

RMA or Warranty: If the device is under warranty or support contract, contact the
vendor for a possible replacement or repair.

Identify the Impact: Assess the impact of the failed device on the network and
affected services.

Redundancy and Failover: Review the network design to ensure proper redundancy
and failover mechanisms are in place to handle device failures.
Replacement and Spare Parts: Keep spare devices or critical components on hand to
quickly replace failed devices when needed.

Document the Failure: Document all the troubleshooting steps, actions taken, and the
resolution for future reference.

By following a systematic troubleshooting approach, you can quickly identify the

failing device and take appropriate steps to address the issue, minimizing network
downtime and ensuring smooth network operation. If the issue is beyond your
expertise, seek assistance from qualified network technicians or engage with vendor
support for further assistance.

Network Problem #14. VPN Connectivity Problems

VPN (Virtual Private Network) connectivity issues are a common network problem that
can hinder remote workers or branch offices from securely accessing the corporate
network. VPNs create encrypted tunnels over the public internet, allowing users to
access internal resources and services as if they were directly connected to the
corporate network.

However, various factors can lead to connectivity problems, preventing users from
establishing or maintaining a stable VPN connection.

I. The Consequences of VPN Connectivity Issues

Limited Remote Access: VPN connectivity issues can restrict remote workers' access
to critical resources and data.

Reduced Productivity: Users may experience delays or interruptions in their work due
to VPN connection failures.

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Security Risks: VPN connectivity problems can prompt users to seek alternative and
potentially insecure ways to access corporate resources.

II. The Causes of VPN Connectivity Issues

Network Congestion: High levels of data traffic or network congestion can impact VPN
performance and lead to connectivity problems.

Firewall or Security Settings: Misconfigured firewalls or security settings can block

VPN traffic, preventing successful connections.

VPN Server Overload: An overloaded VPN server can struggle to handle incoming
connection requests, leading to connection failures.

Client Software Conflicts: Interference from other software or settings on the client
device can cause VPN connectivity issues.

Internet Connection Instability: Unstable or unreliable internet connections can disrupt

VPN connections.

VPN Protocol Issues: Compatibility issues between VPN protocols and devices can
lead to connection problems.

III. How to Identify & Troubleshoot VPN Connectivity Issues

Network Monitoring: Use network monitoring tools like Obkio to track VPN
connectivity metrics and identify potential issues. Obkio has remote network
monitoring features, which is especially important for monitoring remote workers
connectivity towards VPNs.

Firewall and Security Configuration: Review and adjust firewall settings to ensure
VPN traffic is permitted and secure.

VPN Server Load Balancing: Implement load balancing for VPN servers to distribute
connection requests evenly and avoid network overload.

VPN Client Troubleshooting: Troubleshoot VPN client software on user devices to

identify and resolve conflicts or configuration issues.

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Internet Connection Stability: Address internet connection problems on user devices
to ensure a stable VPN connection.

VPN Protocol Selection: Choose appropriate VPN protocols based on device

compatibility and network requirements.

By proactively monitoring and troubleshooting VPN connectivity issues, businesses

can ensure remote workers have reliable access to corporate resources. Network
monitoring, VPN server optimization, and client device maintenance play a vital role in
identifying and resolving VPN connectivity issues, enhancing productivity, and
maintaining a secure remote work environment.

IV. Network Troubleshooting Scenarios for VPN Connectivity Issues

VPN (Virtual Private Network) connectivity issues can prevent users from securely
accessing resources on a remote network. Troubleshooting VPN connectivity
problems requires a careful examination of both client-side and server-side
configurations. Here are some network troubleshooting scenarios to consider when
dealing with VPN connectivity issues:

Check Client Credentials: Verify that the VPN client has the correct username,
password, and any necessary authentication tokens or certificates.

VPN Client Software: Ensure that the VPN client software is installed correctly and up
to date.

VPN Server Status: Check the VPN server's status to ensure it is operational and
accepting connections.

Firewall and Security Software: Temporarily disable any third-party firewalls or

security software that might be blocking VPN connections.

Check VPN Server Logs: Review the VPN server logs for any error messages or
connection attempts from the problematic client.

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Network Address Translation (NAT): If the VPN server is behind a NAT device,
ensure that proper NAT traversal (like NAT-T) is configured.

VPN Protocol: Verify that both the client and server are using the same VPN protocol
(e.g., OpenVPN, PPTP, L2TP/IPsec, IKEv2).

Firewall Rules: Check firewall rules on the VPN server to ensure that incoming VPN
traffic is allowed.

Verify VPN Server and Client IP Addressing: Ensure that there are no IP address
conflicts between the client and server networks.

Internet Connectivity: Verify that both the client and server have a stable internet
connection.

ISP Blocking: Check if the internet service provider (ISP) is blocking VPN traffic. Try
connecting from a different ISP to test.

MTU Settings: Test different Maximum Transmission Unit (MTU) settings on the client
and server to avoid potential fragmentation issues.

VPN Split Tunneling: Confirm that VPN split tunneling is not causing conflicts with
local or remote network access.

Restart VPN Services: Try restarting the VPN server and services.

VPN Routing: Ensure that VPN routing is correctly configured to allow traffic to flow
between client and server.

VPN Server Certificates: Verify that server-side certificates (if used) are valid and not
expired.

Check VPN Encryption Settings: Ensure that both the client and server agree on
encryption and authentication settings.

Temporary Bypass VPN: Temporarily bypass the VPN and test regular internet
connectivity to verify the issue is VPN-specific.

NAT Traversal: If the VPN client is behind a NAT device, ensure that NAT traversal
methods are enabled on both client and server.

Update VPN Client and Server Software: Keep both the VPN client and server
software up to date to address any known issues.
Client and Server Time Sync: Verify that the client and server clocks are
synchronized, as time differences can cause authentication problems.

By systematically troubleshooting VPN connectivity issues, you can identify and

resolve the root causes, allowing users to securely access remote resources over the
VPN. Documenting the troubleshooting steps and actions taken will aid in future
reference and assist others in resolving similar issues. If the issue persists or requires
expertise beyond your capabilities, don't hesitate to seek assistance from qualified
network administrators or VPN specialists.

Network Problem #15. Load Balancing Configuration Errors

Load balancing configuration errors are a common network problem that occurs when
the distribution of network traffic across multiple servers or links is not optimized or
balanced correctly.

Load balancing is a technique used to evenly distribute incoming network requests or

data traffic among multiple resources, ensuring optimal utilization of resources and
preventing overload on individual components. However, misconfigurations or errors
in load balancing setups can lead to uneven distribution, causing performance issues
and potential service disruptions.

I. Consequences of Load Balancing Configuration Errors

Overloaded Servers: Misconfigurations can lead to uneven distribution of traffic,

overburdening certain servers while leaving others underutilized.

Service Degradation: Load balancing errors can cause performance issues, leading to
slow response times and reduced service availability.

User Experience Issues: Users may experience inconsistent service quality or

disruptions due to load balancing problems.

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Increased Downtime Risk: Load balancing configuration errors can increase the risk
of service outages or downtime during peak traffic periods.

II. Causes of Load Balancing Configuration Errors

Incorrect Weighting: Assigning improper weights to servers or links in the load

balancing setup can result in disproportionate traffic distribution.

Inadequate Health Checks: Inaccurate or inadequate health checks on servers can

lead to the inclusion of faulty or overloaded servers in the load balancing pool.

Session Persistence Misconfiguration: Misconfiguring session persistence can cause

users to lose their session data when redirected to different servers.

Improper Load Balancer Placement: Placing the load balancer in an inefficient

location within the network can lead to suboptimal traffic routing.

III. How to Identify & Troubleshoot Load Balancing Configuration Errors

Network Monitoring: Utilize network monitoring tools like Obkio to track server
performance and identify any imbalanced traffic patterns.

Load Balancer Configuration Review: Regularly review load balancer settings and
verify proper weightings and health checks.

Testing and Validation: Conduct network load testing and validation to ensure load
balancing configurations work as intended under different traffic conditions.

Session Persistence Testing: Verify session persistence settings to ensure smooth

user experience during server changes.

Load Balancer Placement: Review the placement of load balancers in the network to
optimize traffic routing.

By proactively identifying and addressing load balancing configuration errors,

businesses can ensure efficient resource utilization, enhance service performance,
and reduce the risk of downtime. Network monitoring, load balancer configuration

reviews, and rigorous testing play a crucial role in detecting and resolving load
balancing configuration errors, improving the overall reliability and network availability
of network services.

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Load balancing configuration errors can lead to uneven distribution of traffic, service
disruptions, and degraded performance. Troubleshooting load balancing issues
requires careful analysis of the load balancer's configuration and associated network
components. Here are some network troubleshooting scenarios to consider when
dealing with load balancing configuration errors:

Check Load Balancer Configuration: Review the load balancer's configuration to

ensure it is set up correctly, including virtual server settings, server pools, and load
balancing algorithms.

Monitor Server Health: Monitor the health and status of the backend servers to ensure
they are properly configured and responsive to requests.

Verify Server Pool Membership: Check that all the intended backend servers are
added to the appropriate server pools and that no servers are mistakenly excluded.

Check Load Balancer Status: Verify that the load balancer is operational and not
experiencing any issues.

Load Balancer Firmware and Software Updates: Keep the load balancer's firmware
and software up to date to address known issues and security vulnerabilities.

Algorithm Selection: Ensure the appropriate load balancing algorithm (e.g., round-
robin, least connections, weighted) is selected based on the specific application and
server requirements.

Monitor Traffic Distribution: Observe the traffic distribution among backend servers to
identify any imbalances.

Session Persistence: Check session persistence settings to ensure that client

requests are directed to the same backend server for the duration of a session, if
required.

Health Checks and Monitors: Review health check settings to ensure they accurately
monitor backend server availability and health.

Virtual IP Address and Network Configuration: Verify that the virtual IP address and
network configuration are properly set up and accessible.

Firewall Rules and Security Groups: Check that firewall rules or security groups are
not blocking the load balancer's traffic

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Service Ports and Protocols: Confirm that the load balancer is configured to forward
traffic to the correct service ports and protocols on the backend servers.

Log Analysis: Analyze load balancer logs for any error messages or indications of
misconfiguration.

Service Check: Use network monitoring tools to perform service checks on the
backend servers to identify any issues.

Load Test and Simulation: Conduct load testing or simulate traffic to observe how the
load balancer handles various loads and conditions.

SSL Certificates: If using SSL termination, verify that the SSL certificates on the load
balancer are valid and not expired.

Application-Specific Configuration: For certain applications, ensure that any

application-specific configurations or settings are correctly configured in the load
balancer.

Backup and Restore Configurations: Keep backups of load balancer configurations

and restore them in case of accidental changes or misconfigurations.

Rollback Changes: If you recently made changes to the load balancer configuration,
consider rolling back the changes to a known working state.

By systematically troubleshooting load balancing configuration errors, you can identify

and resolve issues that affect traffic distribution and optimize the performance and
reliability of the load balancer. Regular monitoring and analysis of traffic patterns will
help you proactively detect and address load balancing issues as they arise. If the
issue persists or is beyond your expertise, seek assistance from qualified network
administrators or load balancing specialists.

Network Problem #16. Link Flapping

Link flapping is a common network problem characterized by the frequent and rapid
oscillation of a network link between the up and down states.

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When a link flaps, it continuously alternates between being connected (up) and
disconnected (down). This rapid and inconsistent behavior can disrupt network
communication, cause service interruptions, and lead to instability within the network
infrastructure.

I. The Consequences of Link Flapping

Network Instability: Frequent link flapping can destabilize the network, leading to poor
performance and service disruptions.

Packet Loss: During link flapping, data packets may be lost or delayed, affecting data
integrity and delivery.

Connectivity Issues: Devices connected to the flapping link may experience

intermittent connectivity or disconnections.

Spanning Tree Protocol (STP) Recalculation Delays: STP recalculations during link
flapping can result in temporary network outages or increased convergence times.

II. The Causes of Link Flapping

Physical Connectivity Issues: Loose or damaged cables, connectors, or network ports

can cause link flapping when there are intermittent connections.

Network Device Errors: Malfunctioning network switches, routers, or network interface

cards (NICs) can lead to unstable link states.

Spanning Tree Protocol (STP) Misconfigurations: Incorrect STP configurations can

create network loops, resulting in link flapping as STP tries to block or unblock
redundant paths.

Ethernet Auto-Negotiation Problems: Inconsistent auto-negotiation settings between

devices can cause link flapping due to mismatched speeds or duplex modes.

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III. How to Identify & Troubleshoot Link Flapping

 Network Monitoring: Use network monitoring tools like Obkio to track link status and
identify instances of link flapping.

Physical Inspection: Physically inspect network cables and connectors to ensure they
are properly connected and not damaged.

Interface Errors: Check for interface errors or error counters on network devices to
identify potential issues.

STP Configuration Review: Review and verify STP configurations to prevent network
loops and link flapping.

Speed and Duplex Settings: Ensure consistent speed and duplex settings between
connected devices to avoid negotiation issues.

Link Redundancy: Evaluate link redundancy and adjust configurations to avoid

unintended loops.

By proactively identifying and addressing link flapping, businesses can maintain a

stable and reliable network infrastructure. Network monitoring, physical inspections,
and STP configuration reviews are essential in detecting and mitigating link flapping
issues, ensuring smooth communication and data transfer within the network.

IV. Network Troubleshooting Scenarios for Link Flapping

Link flapping occurs when a network link experiences frequent up and down
transitions, causing instability and disruptions in communication. Troubleshooting link
flapping requires identifying the underlying causes and implementing solutions to
stabilize the link. Here are some network troubleshooting scenarios to consider when
dealing with link flapping:

Physical Inspection: Inspect the physical connections of the link for loose cables,
damaged connectors, or faulty network equipment.Cable Quality: Check the quality of the
network cables. Use certified and properly shielded cables to reduce interference.

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Link Speed and Duplex Settings: Verify that both ends of the link are set to the same
speed and duplex settings (e.g., 1 Gbps, full duplex) to avoid negotiation issues.

Auto-Negotiation: Test the link with auto-negotiation enabled and disabled to see if it
stabilizes the connection.

Check Network Equipment: Review the logs and statistics of the network switches or
routers connected to the link for any errors or alerts related to the flapping link.

Firmware and Software Updates: Ensure that the firmware and software of network
devices are up to date to address known issues.

STP (Spanning Tree Protocol) Issues: Check if the link is part of a spanning tree loop
or blocked by Spanning Tree Protocol (STP) due to redundancy misconfigurations.

STP PortFast and BPDU Guard: If using STP, ensure that PortFast and BPDU Guard
are configured correctly to prevent accidental loops.

Link Aggregation (EtherChannel/LACP): If the link is part of a link aggregation group,

verify the configuration of the aggregation protocol (e.g., EtherChannel, LACP).

Power Fluctuations: Verify that the devices connected to the link have stable power
sources to prevent link flapping due to power issues.

Update NIC Drivers: Keep network interface card (NIC) drivers up to date on
connected devices to prevent compatibility issues.

Interference: Check for sources of electromagnetic interference or signal degradation

that might affect the link stability.

Port Statistics: Monitor port statistics to check for excessive error counters, collisions,
or other anomalies.

MTU Size: Test different Maximum Transmission Unit (MTU) sizes to avoid potential
fragmentation issues.

Bypass Network Equipment: Temporarily bypass any intermediate network equipment

(e.g., switches, routers) to determine if the issue is specific to a particular device.

Check Other Network Links: Investigate if any other links or devices in the network
are causing network congestion or instability.

Isolate Devices: Isolate devices connected to the link to test if the problem lies with
one of the connected devices.
Network Capture: Use network capture tools to analyze network traffic and look for
patterns or events leading to link flapping.

By systematically troubleshooting link flapping, you can identify the root causes and
implement appropriate solutions to stabilize the link and ensure reliable network
communication. Regular monitoring and analysis of network performance will help
you proactively detect and address link flapping issues as they arise. If the issue
persists or requires expertise beyond your capabilities, seek assistance from qualified
network administrators or network equipment vendors.

How to Troubleshoot the Most Common Network Problems: Steps & Tips

Now that we've gone over some of the most common network problems that
businesses encounter in enterprise networks, it's essential to equip ourselves with
effective troubleshooting steps. When network issues arise, swift and systematic
troubleshooting is crucial to minimize downtime, ensure smooth operations, and
maintain a reliable network infrastructure.

Identifying network issues is the first step to solving them - and it all comes down to
pinpointing who, what, where, and when.

Step 1: Network Assessment

The first step when it comes to identifying network problems, with your Network
Monitoring tool in hand, is performing a network assessment to collect some key
information about your network. Obkio's Network Monitoring tool, which we helped
you deploy earlier in this blog post, plays a vital role in this process.

Get started with Obkio for free!

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By conducting a thorough network assessment, you can gain valuable insights into
your network's health, performance, and potential bottlenecks. This information
serves as a solid foundation for efficient troubleshooting and enables you to pinpoint
the root causes of network issues more effectively. Now, let's delve into the general
troubleshooting steps to address common network problems and make the most out
of your network monitoring capabilities

What actions to take: After you’ve collected all the information you need to identify the
network issue, can then start network troubleshooting. That could include reaching
out to your ISP or MSP, or bringing the problem to your network administrator to fix it
internally.

For all the details about identifying network issues, check out our article on how to
identify network issues!

Troubleshooting common network problems involves identifying the "what" issue is

occurring, determining "where" the problem is located in the network, understanding
"when" the issue is happening, identifying "who" is affected, and then taking
appropriate actions to resolve the problem. Here are some steps to help troubleshoot
common network problems:

Step 2: Identify the Issue (What)

To know how to solve these problems, you need to actually understand what they are.
A network performance monitoring software will measure network metrics and report
back if it finds any issues, with details about what the issue is, and what caused it.

Gather information from users or monitoring tools to determine the symptoms and
specific problem experienced.

Clearly define the issue, such as slow internet speed, intermittent connectivity, or
VoIP call quality problems.

Step 3: Locate the Problem (Where)

It’s important to identify where exactly in your network an issue has occurred. Using
Monitoring Agents, Obkio allows you to deploy Agents in key network locations for
end-to-end visibility over your network to provide you with details about where
problems have occurred. This end-to-end network monitoring approach gives you
visiblity of every end of your network, from your LAN to your WAN.

Determine which part of the network is affected, such as a specific network segment,
device, or service.

Use network monitoring tools and analysis to identify potential network bottlenecks,
high utilization areas, or devices showing errors.

Step 4: Determine the Timeframe (When)

Identifying the specific timeframe in which a network problem occurs is essential for
effective troubleshooting. Pinpointing when the issue started and its recurrence
patterns using historical data from Obkio's NPM tool can help correlate the problem
with network changes or events, streamlining the resolution process.

Find out when the problem started occurring to correlate with any changes in the
network or configurations.

Analyze network logs and timestamps to pinpoint when the issue typically happens, if
it's intermittent.

Step 5. Identify Affected Users (Who)

Understanding which users or devices are experiencing network issues is crucial in

troubleshooting. By pinpointing the affected users, network administrators can focus
their efforts, assess the scope of the problem, and provide targeted support, ensuring
a prompt resolution and improved user experience."

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Determine which users or devices are experiencing the problem to understand the
scope of the issue.

If the problem is widespread, identify common factors among affected users.

Step 6. Who is Responsible For the Network Segment

Once you know where a network problem is located, and what exactly it is, you can
then easily decide who in your business is responsible for that network segment.

Identifying the responsible party helps streamline communication and coordination,

ensuring a more effective and targeted approach to resolving the issue.

By involving the right stakeholders, you can facilitate a faster resolution and prevent
delays in troubleshooting efforts.

Step 7. Take Initial Actions (What Actions to Take)

When network issues arise, it's essential to swiftly address the problem with initial
actions. This step focuses on quick checks and basic troubleshooting to resolve
common issues that might be causing the network problem. By taking these
immediate actions, you can potentially resolve the problem right away or narrow down
the root cause, setting the stage for further targeted troubleshooting.

Perform basic checks, such as verifying cable connections, power cycling affected
devices, or checking for software updates.

Review network configuration changes or recent updates that might have contributed
to the problem.

Step 8. Isolate the Issue

To efficiently troubleshoot network problems, isolating the issue is crucial. This step
involves narrowing down the problematic area or component in the network. By

systematically eliminating potential causes, you can pinpoint the specific source of the
problem, leading to a more precise and effective resolution.
Monitor network devices, like switches or routers, using Obkio's Network Device
Monitoring feature, to identify if they are causing the problem or experiencing
resource issues.

Divide the network into segments and test each segment independently to narrow
down the location of the problem.

Use Visual Traceroutes to determine if the problem is in your local network or ISP
network.

Step 9. Implement Solutions

After identifying the root cause of the network problem, it's time to implement targeted
solutions. This step focuses on making necessary adjustments, configurations, or
replacements to address the issue directly. By applying the appropriate solutions, you
can effectively restore network functionality and prevent the problem from recurring

Based on the gathered information, apply appropriate solutions, such as adjusting

configurations, updating firmware, or replacing faulty hardware.

If the network problem is beyond your organization's control and is related to the
Internet Service Provider (ISP) or Managed Service Provider (MSP network)
infrastructure, promptly reach out to them for assistance.

Collaborating with your ISP or MSP can expedite the resolution process for issues
that lie outside your network's scope.

Document the changes made during troubleshooting for future reference.

Step 10. Test, Verify & Continuously Monitor Network Performance

Culminating the troubleshooting process, this section outlines the essential steps to
verify the effectiveness of the implemented solutions and ensure a stable network
environment. From thorough network testing to continuous monitoring, these
practices ensure that network issues are promptly resolved and potential future
problems are proactively addressed.

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After implementing solutions, thoroughly test and continuously monitor network
performance with your Network Monitoring tool to ensure the problem is resolved.

Verify that the network is functioning as expected and the previously identified issues
are no longer present. Monitor the network post-resolution to verify the stability and
effectiveness of the applied changes.

Continuously monitor network performance using tools like Obkio to ensure the
problem does not reoccur and to detect any new issues that may arise.

By ongoing monitoring, you can proactively address potential problems before they
impact the network's stability and user experience.

Obkio - Common Network Problems

Why Should Businesses Find & Fix Network Problems Anyways?

In this section, we'll delve into why finding and troubleshooting network problems is a
critical mission for businesses. From bolstering productivity and enhancing customer
experience to safeguarding data and gaining a competitive edge, we'll explore the
myriad reasons why proactive network monitoring is an indispensable investment.

Maintaining Productivity: A smooth and reliable network is the backbone of business

productivity. When network problems occur, they disrupt communication, data access,
and collaborative efforts, leading to downtime and decreased efficiency. By identifying
and resolving these issues promptly, businesses can minimize disruptions and keep
productivity levels at their peak.

Enhancing Customer Experience: In a digitally interconnected world, customer

satisfaction hinges on swift and seamless interactions. Network problems can affect
customer-facing services, leading to slow response times, website downtime, and
impaired online transactions. By proactively addressing network issues, businesses
can provide a positive customer experience, which can bolster loyalty and brand
reputation.

Cost Savings: Network problems can be costly in terms of both time and resources.
Extended downtime can result in revenue losses, missed opportunities, and

increased operational expenses as IT teams rush to troubleshoot and fix issues. By

resolving problems swiftly, businesses can mitigate these financial impacts and avoid
potential long-term consequences.

Security and Data Protection: Network problems, especially those related to security
breaches, can expose sensitive data and compromise the overall integrity of the
business. Troubleshooting network vulnerabilities and promptly addressing security
threats is essential for safeguarding valuable information and maintaining regulatory
compliance.

IT Team Efficiency: Persistent network issues can place an immense burden on IT

teams, overwhelming them with repetitive troubleshooting tasks. By proactively
identifying and resolving problems, IT teams can focus on strategic initiatives and
improvements, ultimately making the best use of their expertise and time.

Business Continuity: In today's digital-dependent landscape, uninterrupted business

operations are crucial for survival and growth. Network problems, if left unchecked,
can lead to extended outages and interruptions, threatening business continuity. By
troubleshooting and resolving issues, businesses can ensure a more robust and
resilient infrastructure.

Competitive Advantage: In a competitive market, businesses must deliver a

seamless user experience to stand out from their rivals. A well-maintained and

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efficient network allows companies to differentiate themselves by providing reliable
services and smooth interactions, ultimately gaining a competitive edge.

Employee Satisfaction: A functional network translates to a smoother work experience

for employees. When network problems are addressed promptly, employees can
focus on their tasks without the frustration and stress caused by technology-related
hurdles.

In conclusion, finding and troubleshooting network problems is crucial for businesses

to maintain productivity, enhance customer experience, save costs, protect data,
streamline IT operations, ensure business continuity, gain a competitive advantage,
and foster employee satisfaction. It's an essential investment in the overall success
and growth of any modern business.

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