Networking Essentials II Rev

7/29/2019 Networking Essentials II Rev

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COMPUTER NETWORKING

( Part-II )


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Network Types

Broadly, three types of Networks-

-LAN ( Local Area Network)

-MAN ( Metropolitan Area Network )

-WAN ( Wide Area Network )


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LOCAL AREA NETWORK(LAN)

LANs are usually confined to a Building or a set

of Buildings in a Campus.

LANs are localised & small Networks connected

with a number of Computers .

A number of LANs may be interconnected by

suitable means through Bridges, Routers etc.

LANs are usually connected through Media Cables.Wireless Links are also being used instead of

Media Cables..


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METROPOLITAN AREA

NETWORK(MAN) A MAN is normally designed to extend over a

City.

MANs are connected using Cables, Routers andGateways etc.

Cable Laying for a MAN may be costly and

problematic affairs. In such cases, the concerned

authority may take help of Telecom Service

Providers for hiring of Cables on rental basis.


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WIDE AREA

NETWORKS(WAN) Terminals of a WAN are located at different cities/towns.

A WAN may be implemented by interconnecting a

number of LANs of an organisation located at variousplaces through dedicated or dialup links.

A WAN may be a simple one if number of remote users

are few. But when a large number LANs are

interconnected and more number of users are there, the

set up may become very much complex and it may need

lot of maintenance efforts.


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A TYPICAL COMPUTER NETWORK

11.0.0.0 12.0.0.0 14.0.0.0

Server

Server

Gateway

ExecutiveEngineering Marketing

Internet

Intran

et

DMZ

Internet171.69.236.1

171.69.236.3 171.69.236.4


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TOPOLOGY OF COMPUTER

NETWORKS Topology refers to the arrangements of Computers

and associated elements in a Network.

There are two Topologies--Physical Topology

-Logical Topology

Physical Topology is concerned with the inter-connection of the H/W components of the N/W.

Logical Topology gives information about how the

Communication occurs among the N/W elements.


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PHYSICAL TOPOLOGY

There three primary categories-

-Bus Topology: Here all the Computers are

connected to a common path called Bus.-Star Topology: In this case the N/W componentsare extended from the Server through somedistribution points like Hubs/Switches.

-Ring Topology: It is the case where the N/Welements are connected one after another in theform of a Ring.


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BUS TOPOLOGY NETWORK

A B C D

4321

A sends to 4


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PHYSICAL TOPOLOGY

(Contd.)Apart from above three Topology categories,

there are some other Topology options like-

-Tree Topology which is basically acombination of Bus and Star Topologies.

-Star-Wired Ring Topology which is externallya Star Topology but from working point of viewa Ring Topology.

-Mesh Topology where each Computer hasredundant data paths to some other Computers.


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GENERAL FEATURES OF PHYSICAL

TOPOLOGIES

Bus Topology- Easy to connect terminals &needs less Cable lengths. Maintenance is

not smooth. Star Topology- Easy installation and

maintenance. It requires more cable lengthsand costlier than Bus Topology.

Ring Topology- Point to Point wiring withcomplex procedures to configure.


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LOGICAL TOPOLOGY

Logical Topologies are actually Networking Protocols

which define the rules related to the Communication

between the N/W elements of Networks.

The rules include guidelines that regulate the

following characteristics of a Network-

-Access Method

-Allowed Physical Topologies

-Types of Cablings

-Speed of Data Transfer


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COMMONLY USED

PROTOCOLS The most common protocols are-

-Ethernet

-Local talk

-Token Ring

-FDDI(Fibre Distributed Data Interface )


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ETHERNET

Developed as per IEEE standard 802.3

Works on the principle of CSMA/CD

(Carrier Sense Multiple Access / Collision Detect).

The principle is that if two Computers transmit at

the same time , Collision occurs. So a Computer

listens for sometime before transmission of data and

if the N/W is free then it transmits. Thus Collision is

avoided.


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ETHERNET (Contd.)

Ethernet uses NIC to identify the StationAddress. The NIC has 6-byte physical

address. In order to increase the speed of Ethernet

working, new standards were developed .These are termed as Fast Ethernet.

Now Ethernet working speed goes upto 100mbps.


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LOCAL TALK

A N/W protocol developed by Apple Computers, Inc.

This was meant for Macintosh Computers.

It works on CSMA/CA ( Carrier Sense MultipleAccess / Collision Avoidance )

Here a Computer signals it intents before it transmits.

It can work in Bus, Star etc. Topologies. Speed of transmission is low-230 kbps.


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TOKEN RING

In Ethernet Collision cannot be avoided totally.

So IEEE developed Token Ring according to its standard

known as 802.5

It works on round-robin fashion. Each device is given a Token for certain time and during this

period, it is to perform its job. When time out occurs, it has to

release the Token to the next device and same thing is

repeated. Once a cycle is over, then second cycle will start. It uses NIC with 6-byte station address.

Speed is possible upto 100 mbps with Copper Cables.


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FDDI

Standardised by ANSI and ITU-T.

Initial developments were aiming to overcome the

shortcomings of Ethernet and Token Ring over

Copper Cables.

It uses Fibre Optic Cables instead of Copper Cables.

The arrangements are complex and cost is more.

FDDI uses Token Ring principle for Communicatingand it uses NIC with 6-byte address.

Speed is 100 mbps and even more..


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THANKS

Documents

Networking Essentials II Rev