1 LEC Midterms

7/31/2019 1 LEC Midterms

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NETWORKING

EDATCOM


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Networking

Network - a set of equipments (oftenreferred as data terminal equipment /DTE, or simply terminals or nodes ..)

connected by a communicationchannel, which can be eitherguided/unguided media.


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Uses/Purposes ofNetworking Sharing of

hardware

- Computerhardwareresources

- Disks- Printers..

Sharing of

software

Sharing ofinformation

- Several

individuals caninteract witheach other

- Working ingroups can beformed

Communication


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Uses/Purposes ofNetworking Scalability

- Individual

subsystems canbe created andcombine it into amain system to

enhance theoverallperformance.

Distributedsystems

- In a networked

environmentcomputers candistribute the

work loadamongthemselveskeepingtrans arenc


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Types of Networks

Point to point

Local Area Network (LAN)

Metropolitan Area Network(MAN)

Wide Area Network (WAN)

Value added Network (VAN)


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Types of Networks

Point to point

PC to PC communication using com ports


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Types of Networks

Local Area Network (LAN)

- a small collection of computers in a

small geographic area of less thancouple of kilometers and is very fastin data transfer.

LAN Configurations:

1. Peer-to-peer

2. Client server model


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LAN Configurations

Peer-to-peer

- This configuration is the simplest, but

there is no security.- In this configuration computers are

connected together to share their

recourses among themselves.


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LAN Configurations

Client/server

- In this configuration you can have full

control over security and protection.- describes the relationship between

two computer programs in which one

program, the client, makes a servicerequest from another program, theserver, which fulfills the request.

-

provides a convenient way tointerconnect ro rams that are


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7/27/12 Client server model


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7/27/12 A LAN setup


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Types of Networks

Metropolitan Area Network(MAN)

- designed to cover an entire city.

- Privately laid cables or public leasedlines may be used to form thisnetwork.

Typical

Metropolitan area


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Types of Networks

Wide Area Network (WAN)

- is a data communications network

that covers a relatively broadgeographic area, often a country orcontinent.

- contains a collection of machinescalled hosts intended for runninguser programs.

utilize public, leased, or privatecommunication devices when it


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A typical WAN covering entire United States

Typical WAN setup with hosts, routers andsubnet


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Types of Networks

Value added Network (VAN)

- are communications networkssupplied and managed by third-partycompanies that facilitate electronicdata interchange, Web services andtransaction delivery by providing

extra networking services. a private network provider

(sometimes called a turnkey

communications line) that is hired by


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Types of Networks

#Transaction Delivery Networks(TDN):The newest evolution of VANs,which first appeared in 2000, are the

transaction delivery networks (TDN)that provide services for secure end-to-end management of electronic

transactions.- Also called transaction processing

networks or Internet utility

platforms


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Types of Networks

#Internetworks: Or simply theinternet are those when two or morenetworks are get connected.

Individual networks are combinedthrough the use of routers.


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7/27/12 Typical internetwork connecting LANs

and MANs


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NETWORK

TOPOLOGIES


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Introduction

Topology - defines how the devices(computers, printers..etc) areconnected and how the data flows

from one device to another.

Two conventions for representingtopologies:

1. Physical topology - defines how thedevices are physically wired


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Bus Topology

Physical topology of bus topology

Logical topology illustration of bus


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Bus Topology

In a bus topology all devices areconnected to the transmissionmedium as backbone. There must be

a terminator at each end of the busto avoid signal reflections, which maydistort the original signal. Signal is

sent in both directions, but somebuses are unidirectional. Good forsmall networks. Can be used for10BASE5(thick net), 10BASE2(thinnet) or 10BROAD36 (broad band) co-


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Ring Topology

Ring topology illustration

Ring topology was in the beginning of LAN area. In a ring

topology,each system is connected to the next as shown in thefollowing picture.


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Ring Topology

Each device has a transceiver whichbehaves like a repeater which movesthe signal around the ring; ideal for

token passing access methods. Inthis topology signal degeneration islow; only the device that holds the

token can transmit which reducescollisions. If you see its negativeaspect it is difficult to locate aproblem cable segment; expensivehardware.


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Star topology

Physical topology of Star topology

Logical topology of Startopology


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Star topology

In a star topology each station isconnected to a central node. Thecentral node can be either a hub or a

switch. The star topology does nothave the problem as seen in bustopology. The failure of a media does

not affect the entire network. Otherstations can continue to operate untilthe damaged segment is repaired.

Commonly used for 10BASE5,- -


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Star topology

Advantages:

- cabling isinexpensive

- easy to wire

- more reliable

- easier tomanagebecause of the

use of hubs

Disadvantages:

- all nodesreceive the

same signalthereforedividing

bandwidth- Maximum

computers are1,024 on a LAN

-


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Mesh topology

Physical topology of Mesh topology


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Mesh topology

A mesh physical topology is whenevery device on the network isconnected to every device on the

network; most commonly used inWAN configurations Helps find thequickest route on the network;

provides redundancy. Very expensiveand not easy to set up.


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Hybrid topology

A hybrid topology is a combination ofany two or more network topologiesin such a way that the resulting

network does not have one of thestandard forms. For example, a treenetwork connected to a tree network

is still a tree network, but two starnetworks connected together exhibithybrid network topologies. A hybridtopology is always produced when

two different basic network

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1 LEC Midterms