Network ?
A collection of computing devices that are connected in
various ways in order to communicate and share
resources are Called as Networking.
The N/w Connection May be
1. Wired or 2. Wireless
The purpose of a network is :-
1. Communication 2. share resources.
A resource may be:
A file / folder / printer / disk drive …etc.
A Simple Network
Advantages of networking
Communication
Data Sharing
Hardware Sharing
Internet Access Sharing
Data Security and Management
Entertainment
The Disadvantages of Networking
Hardware & Software Management and
Administration is little bit difficult
Data Security Concerns
Bandwidth
Data rate measured in bits per seconds [ not bytes ]
Kbps (Kilobits per seconds)
125 chars/sec
Mbps (Megabits per seconds)
1,250 chars/sec
Gbps (Gigabits per seconds)
12,500 chars/sec
3 Types of Transmission Modes
Simplex
One direction
e.g. Television
Half duplex
Either direction, but
only one way at a time
e.g. police radio
Full duplex
Both directions at the
same time
e.g. telephone
Communication Types
Unicasting (one-to-one)
Multicasting (one-to-many)
Broadcasting (one-to-all)
Network Classification
3 Types
By
1. Size
2. Structure
3. Topology
Network Classification
1. By Size / Scale
1. LAN
2. WAN
3. MAN
4. CAN
5. PAN
The Local Network - [ LAN ]
Client Client
Client Client
Client Client
Wide Area Network – [ WAN ]
Metropolitan Area Network - [ MAN ]
Campus Area Networks [ CAN ]
A LAN in one large geographic area
Resources related to the same organization
Each department shares the LAN
Personal Area Network - [ PAN ]
Very small scale network
Range is less than 2 meters
Ex : - WiFi Network
Network Classification
2. By Structure / Functional Relationship
1. Peer to Peer (P2P)
2. Client / Server
Peer-to peer network
A peer-to-peer network is a network where the computers
act as both workstations and servers.
Peer to peer network
Client / Server - Networking
In this design, a small number of computers are
designated as centralized servers and given the task of
providing services to a larger number of user machines
called clients .
Client/Server Networking
Network Classification
3. By - Topology / Physical Connectivity
1. BUS
2. STAR
3. RING
4. MESH
5. TREE
BUS
Also called linear bus
One wire connects all nodes
Terminator ends the wires
Advantages
Easy to setup
Small amount
of wire
Disadvantages
Slow
Easy to crash
STAR
All nodes connect to a hub
Packets sent to hub
Hub sends packet to destination
Advantages
Easy to setup
One cable can not crash network
Disadvantages
-One hub crashing downs entire network
Uses lots of cable
Most common topology
RING
Nodes connected in a circle
Tokens used to transmit data
Nodes must wait for token to send
Advantages
Time to send data is known
No data collisions
Disadvantages
Slow
Lots of cable
MESH
All computers connected together
Internet is a mesh network
Advantage
Data will always be delivered
Disadvantages
Lots of cable
Hard to setup
TREE
Hierarchal Model
Advantages
Scaleable
Easy Implementation
Easy Troubleshooting
Intranet vs. Internet
Intranet
A private network that is contained within an enterprise
Could be LANs and WANs
Internet
A public network of networks
Both are using TCP/IP
Devices Needed for Making N/W
Computers & Servers
Network Interface Card (NIC)
Repeater
Hub
Switch
Bridge
Routers
Modem
Cables
Network Interface Card (NIC)
NIC provides the physical interface between computer and
cabling.
The following factors should be taken into consideration when
choosing a NIC:
1. - Preparing data
2. - Sending and controlling data
3. - Configuration
4. - Drivers
5. - Compatibility
6. - Performance
Repeaters
Repeaters are very simple devices. They allow a cabling
system to extend beyond its maximum allowed length by
amplifying the network voltages so they travel farther.
Repeaters can only be used to regenerate signals between
similar network segments.
For example, we can extend an Ethernet 10Base2 network to
400 meters with a repeater. But can’t connect an Ethernet and
Token Ring network together with one.
Repeaters
Hubs
Hubs are devices used to link several computers
together.
They repeat any signal that comes in on one port and
copy it to the other ports (a process that is also called
broadcasting).
There are two types of hubs: active and passive.
Passive hubs simply connect all ports together
electrically and are usually not powered.
Active hubs use electronics to amplify and clean up the
signal before it is broadcast to the other ports.
In the category of active hubs, there is also a class called
“intelligent” hubs, which are hubs that can be remotely
managed on the network.
Hubs
Switch
A network switch is a computer networking device that
connects network segments.
Network switches are capable of inspecting data packets as they
are received, determining the source and destination device of
that packet, and forwarding it appropriately.
By delivering each message only to the connected device it was
intended for, a network switch conserves network bandwidth
and offers generally better performance than a hub.
A vital difference between a hub and a switch is that all the
nodes connected to a hub share the bandwidth among
themselves, while a device connected to a switch port has the
full bandwidth all to itself.
Switch
Bridges
They join similar topologies and are used to divide
network segments.
For example, with 200 people on one Ethernet segment, the
performance will be mediocre, because of the design of
Ethernet and the number of workstations that are fighting to
transmit. If you divide the segment into two segments of 100
workstations each, the traffic will be much lower on either
side and performance will increase.
Unlike repeaters, bridges can filter out noise.
The main disadvantage to bridges is that they can’t connect
dissimilar network types or perform intelligent path
selection. For that function, you would need a router.
Bridges
Routers
Routers are highly intelligent devices that connect multiple
network types and determine the best path for sending data.
The advantage of using a router over a bridge is that routers
can determine the best path that data can take to get to its
destination.
Like bridges, they can segment large networks and can filter
out noise.
However, they are slower than bridges because they are more
intelligent devices; as such, they analyze every packet, causing
packet-forwarding delays. Because of this intelligence, they are
also more expensive.
Routers are normally used to connect one LAN to another.
Typically, when a WAN is set up, there will be at least two
routers used.
Routers
Devices Function at Layers
D e v ic
Types of N/W Cables
* Coaxial
* Twisted pair
* Fiber optic
• Serial Cable
• Console Cable
[Twisted pair Cable can be used as
a.Straight Through Cable
b.Cross Over Cable
c.Roll Over Cable ]
Coaxial Cable
Coaxial Cable Connector
Serial Cable
Fiber-optic cable
Data is transmitted with light pulses
Glass strand instead of cable
Immune to interference
Very secure
Hard to work with
Speeds up to
100 Gbps
STRAIGHT TIP (ST) CONNECTOR
Twisted-pair cabling
Most common LAN cable
Called Cat5 or 100BaseT
Four pairs of copper cable twisted
May be shielded from interference
Speeds range from
1 Mbps to 1,000 Mbps
UTP CONNECTORS [ Rj 45 ]
Wiring within a twisted pair cable is configured as
either
Straight through, where each wire (or pin) is
attached to the same contact point at each end.
Crossover, where transmit contacts on each end of
the cable are connected to the receive contact at the
other end
STRAIGHT THROUGH WIRING
CROSSOVER WIRING
RollOver Wiring
Sl.n Cable Name Used to
o
1 Straight through Cable a. Connect the Computers
[ Different Types of Devices ] with Hubs / Switches
b. Connect the Switches &
Routers
2. Cross Over Cable a. Connect 2 Computers
[ Similar Types Devices ] b. Connect 2 switches
c. Connect 2 Hubs
d. Connect the Computer
with the Router
3. Console Cable Connect the computer’s
RS232 Port with the
router’s Console Port .
4. Serial cable Connect 2 Routers
Protocols
Protocols are agreed sets of rules and procedures for
computers to exchange information.
Like humans agreeing to speak the same language during
a conversation.
For two computers to exchange data, they must be using
the same protocols.
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Network Protocols
There is a standard protocol for each network communication
task, such as:
- To send data over the Internet (TCP/IP)
- To send and receive email (POP, IMAP)
- To request and deliver web pages (HTTP)
- To request and deliver files (FTP)
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The King of Protocols – TCP/IP
A family of protocols that makes the Internet works
It’s a universal protocol for internet communications.
It’s the backbone of the internet.
Made up of 2 complementary protocols…
TCP [ Transport Control Protocol ]
and
IP [ Internet Protocol ]
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TCP/IP – invented in 1973 by Vint Cerf
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Protocols of - TCP/IP Protocol Suite
Routing Protocols
• Routing Information Protocol (RIP)
describes how routers exchange routing table
information
uses hop-count as the metric of a path's cost
• Open Shortest Path First Protocol (OSPF)
more robust, scalable protocol than RIP
doesn't exchange entire tables, only updates changed
links
• Internet Control Message Protocol (ICMP)
adjunct to IP, notifies sender (or other router) of
abnormal events
e.g., unreachable host, net congestion
Three Kinds of Identifiers
Host name (e.g., www.cnn.com)
IP address (e.g., 64.236.16.20)
Numerical address appreciated by routers
Related to host’s current location in the topology
Hierarchical name space of 32 bits
MAC address (e.g., 00-15-C5-49-04-A9)
MAC Address [Media Access Control address ]
A MAC address is a unique identifier assigned to network interfaces for
communications on the physical network segment.
The format will be any one of the following
1. MM:MM:MM:SS:SS:SS 2. MM-MM-MM-SS-SS-SS
The first half of a MAC address contains the ID number of the
adapter manufacturer. The second half of a MAC address
represents the serial number assigned to the adapter by the
manufacturer. In the following example,
00:A0:C9:14:C8:29 The prefix 00A0C9 indicates manufacturer
Dell : 00-14-22
Nortel: 00-04-DC
Cisco : 00-40-96
Mapping Between Identifiers
Domain Name System [ DNS ]
Given a host name, provide the IP address
Given an IP address, provide the host name
Dynamic Host Configuration Protocol [DHCP ]
Given a MAC address, assign a unique IP address
… and tell host other stuff about the Local Area Network
To automate the boot-strapping process
Address Resolution Protocol [ ARP ]
Given an IP address, provide the MAC address
To enable communication within the Local Area Network
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Subnetting
Divide the Network into small group of n/w for easy
Administration.
Using Host IDs to Subnet
140 15 1 0
Subnet 1
Class B Network
140 15 0 0 140 15 2 0
Subnet 2
140 15 3 0
Third octet is now used for subnet IDs Subnet 3
Subnet Configuration
Subnet ID
140 15 1 0
140 15 1 1 ….. 140 15 1 254
First Host ID Last Host ID
Network [ Reference ] Models
OSI TCP/IP
Application Layer
Application Layer
Presentation Layer TELNET, FTP, SMTP, POP3, SNMP,
NNTP, DNS,NIS, NFS, HTTP, ...
Session Layer
Transport Layer Transport Layer
TCP , UDP , ...
Network Layer Internet Layer
IP , ICMP, ARP, RARP, ...
Data Link Layer
Link Layer
FDDI, Ethernet, ISDN, X.25,...
Physical Layer
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SUMMARY
Network
Bandwidth
Transmission Modes[ Simplex , HalfDuplex ,
fullDuplex]
Communication Types[ unicost ,multi , broad ]
3 – Types of Network Classification
[1. Size 2. Structure 3.Topology ]
Intranet vs. Internet
Devices Needed for Making N/W
Protocols
Three Kinds of Identifiers
Sub Netting
Network [ Reference ] Models
