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WAN Technologies

WAN TECHNOLOGIES

Version 3.0Cisco Regional Networking Academy

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Objectives

Examines some of the options available for WANinterconnections, the hardware needed toimplement them, and the terminology used to

discuss them.

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Table of Content

1 WAN technologies overview2 WAN technologies

3 WAN design

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WAN TECHNOLOGIES OVERVIEW

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WAN technology

A WAN is a data communications network thatoperates beyond the geographic scope of a LAN

A company or organization must subscribe to anoutside WAN service provider in order to use WANcarrier network services

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Part of WAN service

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Subscriber to Provider Interface

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WAN Devices

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WAN standard: The physical layer

The physical layer protocols describe how toprovide electrical, mechanical, operational, andfunctional connections to the services provided by a

communications service provider.

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Physical layer standard

EIA/TIA-232: Up to 64 kbps. ~V.24, RS-232.

EIA/TIA-449: Up to 2 Mbps, capable of longer cableruns.

EIA/TIA-612/613: HSSI, Access to services at T3,E3 and SONET STS-1 rates.

V.35: An ITU-T standard, synchronous.

X.21: An ITU-T standard, synchronous.

G.703: An ITU-T specification, operating at E1 datarates.

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Datalink Layer

The data link layer protocols define how data isencapsulated for transmission to remote sites, andthe mechanisms for transferring the resulting

frames.

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Data link layer: WAN protocols

Frame Relay: Transmit data very rapidly comparedto the other WAN protocols.

PPP: Described by RFC 1661, PPP was developed by

the IETF.

ISDN: Digital services that transmits voice and dataover existing phone lines.

LAPB: LAPB provides reliability and flow control on apoint-to-point basis.

HDLC: An ISO standard, HDLC might not becompatible between different vendors.

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WAN encapsulation

Flag Header Data FCS Flag

Address Control Protocol

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Packet and circuit switching

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WAN Link options

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WAN TECHNOLOGIES

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Analog dialup

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ISDN

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Leased line

CSU/DSU

CSU/DSU

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X.25

CSU/DSU

CSU/DSU

CSU/DSU

SVC

PVC

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Frame Relay

CSU/DSU CSU/DSU

PVC

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ATM

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DSL

Service Download Upload

ADSL 1.544-8.192Mbps 16-640Kbps

SDSL 1.544-2.048Mbps 1.544-2.048Mbps

HDSL 1.544-2.048Mbps 1.544-2.048Mbps

IDSL 144Kbps 144Kbps

RADSL 64Kbps-8.192Mbps 16-768Mbps

CDSL 1Mbps 16-160Kbps

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Cable modem

Enhanced cable modems enable two-way, high-speed data transmissions using the same coaxiallines that transmit cable television

A cable modem is capable of delivering up to 30 to

40 Mbps of data on one 6 MHz cable channel

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WAN DESIGN

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Steps in WAN design

LOCATE LANs

ANALYZE TRAFFICS

PLAN TOPOLOGY

PLAN BANDWIDTH

CHOOSE TOPOLOGY

COST AND EVALUATE

Iterate

Review

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How to identify and select networking capabilities

Selecting an interconnection pattern or layout forthe links between the various locations

Selecting the technologies for those links to meet

the enterprise requirements at an acceptable cost

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Three-layer design model

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Other WAN design considerations

Security

Server placement in WANs

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Summary

Familiarity with WAN terminology describingequipment, such as CPE, CO, local loop, DTE, DCE,CSU/DSU, and TA

Familiarity with WAN terminology describing servicesand standards, such as ISDN, Frame Relay, ATM, T1,HDLC, PPP, POST, BRI, PRI, X.25, and DSL

Elements of WAN design, including upgrading,extending, modifying an existing WAN, andrecommending a WAN service to an organizationbased on its needs

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Q&A

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