1 Data Transmission and Computer Networks Local Area Networks.

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Data Transmission and Computer Networks

Local Area Networks

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LAN Topics

LAN Topology

LAN Transmission Media & Devices

LAN Architecture

LAN Medium Access Protocol

LAN Standards

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Wired LAN

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Wired LAN Topology

1. Star:

2. Ring:

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Wired LAN

Topology:

3. Bus:

Bus extender

Bus

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Wired LAN

Topology:

4. Hub:

5. Hub/Tree:

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Wired LAN

Transmission Media:

• Twisted Pair : UTP & STP

• Coaxial Cable : Broadband , Thick & Thin

• Fiber Optics cables

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Wired LAN

Twisted Pair Transmission Media:

• Twisted Pair Types : UTP & STP

• LAN Twisted pair media standards : – 10 Base T– 100 Base TX– 100 Base T4– 1000 Base T– 1000 Base CX

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Wired LAN

Fiber Transmission Media:

• Fiber Cable : Multimode , Single Mode

• LAN Fiber Cable standards :

– 10 Base F : 10 Base FP , 10 Base FL , 10 Base FB

– 100 Base FX– 1000 Base SX– 1000 Base LX Connector SC

Cable with Connector ST

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Wired LAN

Coaxial Transmission Media:

• Coaxial Cable Types : Broadband , Thick , Thin

• LAN Coaxial Cable standards : – 10 Broad 36– 10 Base 5– 10 Base 2

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Wired LAN Standards Comparison

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Wired LAN Standards Comparison

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Wired LAN

Transmission Media:

10BASE T

Twisted Pair

Controller

Hub

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Wired LAN

Transmission Media:

1. Twisted Pair (10BASE T):HUB

Repeater electronics

Rx/Tx circuits

نوع موصلMAU لالسالك STP المزدوجةالشبكات في

الحلقية

صدفة نوع موصل D-shell

ونهاية كبل

RJ-45 المزدوجة االسالك

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Wired LAN

Transmission Media:

Transceiver cable

Transceiver + Controller

10BASE 2

BNC T Connector

Controller

Vampire tap

Core

10BASE 5

Transceiver

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Wired LAN

Transmission Media:

2. Baseband Coaxial Cable:

ii. Thick wire (10BASE 5):

0.5” coaxTransceiver

i. Thin wire (10BASE 2):

Terminator 0.25” coax

BNC T Connector

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Wired LAN Devices

Network Interface Card (NIC)

Hub

Switches

Bridges

Router

Gateway

Repeater

Bridge

المج مع

Hub

القناة الواردة

Input Line

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Wired LAN Devices

Hub Device : Stacked , Stand Alone & Modular

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Wired LAN Devices

Switch Device : Intelligent Hub

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Wired LAN Devices

Router : Connects WAN with LAN

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Wired LAN DevicesNetwork Interface Card (NIC):

Irrespective of the transmission media being used, the communications controller card within each DTE comprises the following:

A medium access controller (MAC) unit: It is responsible for:

• Encapsulation and de-encapsulation of frames.

• Error detection.• Implementation of MAC

algorithm.RAM: It allows MAC unit to receive and transmit frames at he high link bit rate.

RG45

BNCمنفذ

AUIمنفذ

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LAN ARCHITECTURE

LAN Architecture includes:

LAN Model

LAN Layers

LAN Data Link Sub layers and Protocols:

• Logical Link Control LLC sub-layer

( to do data link tasks e.g. error control ..)

• Medium Access Control MAC sub-layer

(to allow sharing LAN medium)

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LAN IEEE REFERENCE MODEL

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LAN Layers data units

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LLC Packet Data Unit PDU & MAC Frame

DSAP: Destination Service Access Point SSAP: Source Service Access Point