 Bandwidth

 Throughput
Like bandwidth, throughput is the measure of the transfer of bits across the media over a given
period of time. However, due to a number of factors, throughput does not usually match the
specified bandwidth. Many factors influence throughput including:
The amount of data being sent and received over the connection
The types of data being transmitted
The latency created by the number of network devices encountered between source and destination
Latency refers to the amount of time, including delays, for data to travel from one given point to
another.
  Detailed Notes on IP Ranges
1. Overview of IP Addressing
An IP (Internet Protocol) address is a unique identifier assigned to each device connected to
a network, allowing communication between them. IP addresses come in two main versions:
 IPv4 (Internet Protocol version 4): A 32-bit address, represented by four numbers (0-
255) separated by periods (e.g., 192.168.0.1).
 IPv6 (Internet Protocol version 6): A 128-bit address, represented by eight groups of
four hexadecimal digits separated by colons (e.g.,
2001:0db8:85a3:0000:0000:8a2e:0370:7334).
IPv4 is still the most commonly used, so we'll focus on IPv4 ranges here.
2. Classes of IPv4 Addresses
IPv4 addresses are divided into five primary classes, from Class A to Class E, with each class
serving a different purpose. Below is a breakdown of the classes:
Class A
 Range: 1.0.0.0 to 126.255.255.255
 Default Subnet Mask: 255.0.0.0
 Use: Large networks (e.g., ISPs, large corporations)
 Number of Networks: 128 (2^7 - 2; excludes 0 and 127)
 Hosts per Network: 16,777,214 (2^24 - 2)
Class B
 Range: 128.0.0.0 to 191.255.255.255
 Default Subnet Mask: 255.255.0.0
 Use: Medium-sized networks (e.g., universities, companies)
 Number of Networks: 16,384 (2^14)
 Hosts per Network: 65,534 (2^16 - 2)
Class C
 Range: 192.0.0.0 to 223.255.255.255
 Default Subnet Mask: 255.255.255.0
 Use: Small networks (e.g., small businesses, home networks)
 Number of Networks: 2,097,152 (2^21)
 Hosts per Network: 254 (2^8 - 2)
Class D
  Range: 224.0.0.0 to 239.255.255.255
 Use: Multicast addressing (for group communication)
 No Subnetting is used for Class D, as it is for broadcasting data to multiple
destinations.
Class E
 Range: 240.0.0.0 to 255.255.255.255
 Use: Experimental (reserved for research and future use)
 Not used in practical networking.
3. Private IP Address Ranges
Private IP addresses are not routable on the public internet and are used for internal
networks (e.g., home, office networks). The ranges for private IP addresses are:
 Class A: 10.0.0.0 to 10.255.255.255
 Class B: 172.16.0.0 to 172.31.255.255
 Class C: 192.168.0.0 to 192.168.255.255
These ranges are reserved for private use, meaning they can't be used as public IP
addresses on the internet. Instead, devices in a private network use Network Address
Translation (NAT) to connect to the public internet.
4. Public IP Address Ranges
Public IP addresses are globally unique and are used for devices directly connected to the
internet. They are allocated by the Internet Assigned Numbers Authority (IANA) and
regional Internet registries (RIRs). They do not fall into the private ranges listed above.
5. Special Purpose IP Ranges
There are some special IP ranges reserved for specific purposes:
 Loopback Addresses: 127.0.0.0 to 127.255.255.255
o Used for testing network software on a local machine. The most common
address is 127.0.0.1, known as "localhost."
 Link-Local Addresses: 169.254.0.0 to 169.254.255.255
o Used for automatic IP addressing when a device cannot obtain an IP address
from a DHCP server.
 Multicast Addresses: 224.0.0.0 to 239.255.255.255
o Used for multicast groups (e.g., video streaming, online gaming).
 Broadcast Address: The address 255.255.255.255 is used for broadcasting messages
to all devices in a network.
6. Subnetting
Subnetting involves dividing a large network into smaller subnetworks (subnets). This is done
by modifying the subnet mask, which determines which portion of an IP address represents
the network and which part represents the host.
Example:
 An IP address of 192.168.1.0/24 has a subnet mask of 255.255.255.0, indicating 256
IP addresses (0-255). Here, /24 means the first 24 bits are network bits, and the
remaining 8 bits are for hosts.
7. CIDR (Classless Inter-Domain Routing) Notation
CIDR allows more flexible allocation of IP addresses than traditional class-based networks by
using a prefix to specify the number of bits that represent the network portion.
Example:
 192.168.1.0/25 indicates the first 25 bits are network bits.
 A /25 network means 128 possible IP addresses (half of a Class C block).
8. Summary of IP Ranges
Range Type Purpose

10.0.0.0/8 Private (Class A) Internal use (large nets)

172.16.0.0/12 Private (Class B) Internal use (med nets)

192.168.0.0/16 Private (Class C) Internal use (small nets)

127.0.0.0/8 Loopback Local testing

169.254.0.0/16 Link-Local Auto IP assignment

224.0.0.0 to 239.255.255.255 Multicast Multicast communication

240.0.0.0 to 255.255.255.255 Reserved Experimental use

9. Binary Representation of IP Ranges
Each IP address is composed of 4 octets (in IPv4), and each octet is an 8-bit number.
Understanding the binary form is crucial for subnetting.
Example:
 IP Address 192.168.1.1 in binary: 11000000.10101000.00000001.00000001.
10. Key Terms to Remember
 Network Address: The first address in a subnet, representing the entire network.
 Broadcast Address: The last address in a subnet, used to communicate with all
devices in the network.
 Host Address: The remaining addresses between the network and broadcast
addresses, assigned to devices.
  Clients and Servers (Centralized)

All computers connected to a network that participate directly in network communication

are classified as hosts. Hosts can send and receive messages on the network. In modern
networks, computer hosts can act as a client, a server, or both, as shown in the figure. The
software installed on the computer determines which role the computer plays.

This figure depicts a client PC and a server connected through a cloud symbolizing the
Internet
ClientInternetServer

 Peer-to-Peer Networks(De-Centralized)
Client and server software usually run on separate computers, but it is also possible for one
computer to run both client and server software at the same time. In small businesses and
homes, many computers function as the servers and clients on the network. This type of
network is called a peer-to-peer (P2P) network.

The simplest P2P network consists of two directly connected computers using either a wired
or wireless connection. Both computers are then able to use this simple network to
exchange data and services with each other, acting as either a client or a server as necessary.

Multiple PCs can also be connected to create a larger P2P network, but this requires a
network device, such as a switch, to interconnect the computers.

The main disadvantage of a P2P environment is that the performance of a host can be
slowed down if it is acting as both a client and a server at the same time. The figure lists
some of the advantages and disadvantages of peer-to-peer networks.
In larger businesses, because of the potential for high amounts of network traffic, it is often
necessary to have dedicated servers to support the number of service requests.

The advantages and disadvantages of P2P networking are summarized in the figure.
The figure shows a small network with three devices. A printer is on the left, connected to a
print sharing PC in the middle, which is also connected to a file sharing PC on the right.
Under the topology is a list of the advantages and disadvantage of peer-to-peer networking.
The advantages of peer-to-peer networking are: easy to set up, less complex, lower cost
because network devices and dedicated servers may not be required, and can be used for
simple tasks such as transferring files and sharing printers. The disadvantages of peer-to-
peer networking are: no centralized administration, not as secure, not scalable, all devices
may act as both clients and servers which can slow their performance.
I have a printer to shareI have files to sharePrint SharingFile Sharing

The advantages of peer-to-peer networking:

Easy to set up
Less complex
Lower cost because network devices and dedicated servers may not be required
Can be used for simple tasks such as transferring files and sharing printers
The disadvantages of peer-to-peer networking:

No centralized administration
Not as secure
Not scalable
All devices may act as both clients and servers which can slow their performance


  ISP Services
An Internet Service Provider (ISP) provides the link between the home network and the
internet. An ISP can be the local cable provider, a landline telephone service provider, the
cellular network that provides your smartphone service, or an independent provider who
leases bandwidth on the physical network infrastructure of another company.

Many ISPs also offer additional services to their contract subscribers, as shown in the figure.
These services can include email accounts, network storage, and website hosting and
automated backup or security services.

ISPs are critical to communications across the global internet. Each ISP connects to other
ISPs to form a network of links that interconnect users all over the world. ISPs are connected
in a hierarchical manner that ensures that internet traffic generally takes the shortest path
from the source to the destination.

The internet backbone is like an information super highway that provides high-speed data
links to connect the various service provider networks in major metropolitan areas around
the world. The primary medium that connects the internet backbone is fiber-optic cable.
This cable is typically installed underground to connect cities within continents. Fiber-optic
cables also run under the sea to connect continents, countries, and cities.
ISP Connections
The interconnection of ISPs that forms the backbone of the internet is a complex web of
fiber-optic cables with expensive networking switches and routers that direct the flow of
information between source and destination hosts. Average home users are not aware of
the infrastructure outside of their network. For a home user, connecting to the ISP is a fairly
uncomplicated process.
As shown in the bottom portion of the figure, a router is required to securely connect a
computer to an ISP. This is the most common connection option. It consists of using a
wireless integrated router to connect to the ISP. The router includes a switch to connect
wired hosts and a wireless AP to connect wireless hosts. The router also provides client IP
addressing information and security for inside hosts.