introduction to lan and wan.pdf

8/10/2019 Introduction to LAN and WAN.pdf

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CS341: Introduction to LAN & WAN

Justinian Anatory –Computer and Systems Engineering

Introduction Different Networks

LAN MAN

WAN

Internetwork Networking Devices

WAN technologies

Dedicated

circuit switched

packet switched

narrowband - Analog modem, ISDN

broadband - DSL, Cable modem, SONET



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Networks Categories



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Local Area Networks



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Local Area Networks (II)



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Metropolitan Area Network



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Wide Area Networks Connect devices separated by

wide geographical areas Use Carriers.

They use serial connections of

various types to access

bandwidth over largegeographic

Operate at the Physical and

Data Link layers (Layers 1 &2).



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Internetwork



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WAN Technologies

WAN Technologies OverviewWAN Technologies Overview

Dedicated

• T1, E1, T3, E3

• xDSL

• SONET

Analog

• Dial-up modems

• Cable modems

• Wireless

Switched

CircuitSwitched

• POTS

• ISDN

Packet

Switched

• X.25

• Frame

Relay



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Networking Devices Routers

offer many services, including internetworking and WAN interface ports

Switches

provide connectivity for voice, data, and video communication

Modems

Interface with voice-grade connection to convert analog signal to digital.

Also called CSU/DSUs (channel service units/digital service units) in data

service networks

Represents the DCE side of the DTE/DCE connection



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Circuit Switched: POTS

Plain Old Telephone System (POTS)

also known as Public Switch Telephone Network (PSTN) an important component of our communication infrastructure

It is still the standard for designing reliable networks



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Analog data Services Dial-up Modems (switched analog)

Standard that can provides 56 kbps download speed and 33.6 kbps

upload speed.

With the download path, there is a

digital-to-analogue conversion at

the client side. With the upload path, there is a

analogue-to-digital conversion at

the client side.A-to-D conversion

introduces quantization errormaking the overall s/n ratio lower.

Hence, the upload path can not

support a data rate as high as the

download path



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WAN Data-Link

WAN data link protocols describe how frames are carried between

systems on a single data link. They include protocols designed to operate over dedicated point-to-point,

multipoint, and multi-access switched services.

WAN standards are defined and managed by a number of recognizedauthorities, including the following agencies: ITU-T, ISO, IETF, & EIA



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WAN Data-Link Encapsulations High-Level Data Link Control (HDLC)

Cisco default encapsulation; typically used between routers running

Cisco IOS

Streamlined: no windowing or flow control

may not be compatible with different vendors because of the way each

vendor has chosen to implement it.

HDLC supports both point-to-point and multipoint configurations

Frame Relay frame format

uses simplified framing with no error correction mechanisms

send Layer 2 information much more rapidly than other WAN protocols

PPP (Point-to-Point Protocol)

Developed by IETF; replacing SLIP

Contains a field to identify the network layer protocol

PPP can check for link quality during connection establishment



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Digital Subscriber Lines Digital Subscriber Lines (xDSL); the x stands for a family of technologies

The Asymmetric Digital Subscriber Line (ADSL)

uses most of the bandwidth (up to 8 Mbps) for the downstream and

only a small bandwidth (up to 640 kbps) for the upstream

many Telcos have already installed high-speed digital wide-area

network.

The link between subscribers and network is still analog line from

plain old telephone service lines (POT).



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Cable Modems (Shared Analog) Cable TV provides residential premises with a coaxial cable that has a bandwidth

of 750MHz

The bandwidth is divided into 6 MHz band using FDM for each TV channel A "Cable Modem" is a device that allows high-speed data access (Internet) via

cable TV network.

A cable modem will typically have two connections because a splitter delivers the

TV bands to TV set and the internet access bands to PC via a cable box

The splitter delivers the TV bands to TV set and the internet access bands to PC

via a cable box



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Summary

LAN Basics

WAN Basics Circuit Switch Network

POTS, PSTN, ISDN, leased line, majority of voice circuits, GSM

Packet Switch Network X.25, FR, ATM, Ethernet, FastEthernet, ATM (cell switch)

WAN data link

Analog data service, ISDN, ADSL, Cable Model

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