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KAUSHAL M SHAH (AVPTI)KAUSHAL M SHAH (AVPTI)

Prepared By

Rudri B Jani

Kaushal M Shah

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Introdution

!ra"e Relay (!R) is a hi#h$per%or"ane &A'protool that operates at the physial and datalinlayers o% the SI re%erene "odel*

!R ori#inally +as desi#ned %or use arossInte#rated Ser,ie -i#ital 'et+or (IS-')

inter%aes*Today. it is used o,er a ,ariety o% other net+or

inter%aesas +ell*

!R is an e/a"ple o% a paet$s+ithedtehnolo#y*

Paet$s+ithed net+ors ena0le end stations todyna"ially share the net+or "ediu" and thea,aila0le 0and+idth*

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&hat is !ra"e Relay23A paet$s+ithin# protool %or onnetin# de,ies on

a &ide Area 'et+or (&A')4 5uoted %ro" &e0opedia*

!R net+ors in the U*S* support data trans%er rates atT$6 (6*788 M09s) and T$: (87 M09s) speeds* In %at. youan thin o% !ra"e Relay as a +ay o% utili;in# e/istin#

T$6 and T$: lines o+ned 0y a ser,ie pro,ider* Mosttelephone o"panies no+ pro,ide !R ser,ie %orusto"ers +ho +ant onnetions at 7< K09s to T$6speeds* (In =urope. !R>s speeds ,ary %ro"

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!ra"e Relay ? @*17!R o%ten is desri0ed as a strea"lined ,ersion o% @*17.

oerin# %e+er o% the ro0ust apa0ilities. suh as+indo+in# and retrans"ission o% last data that are oeredin @*17*

This is 0eause !R typially operates o,er &A' %ailitiesthat oer "ore relia0le onnetion ser,ies and a hi#her

de#ree o% relia0ility than the %ailities a,aila0le durin# thelate 6CDs and early 6EDs that ser,ed as the o""onplat%or" %or @*17 &A's*

!R is stritly a Layer 1 protool suite. +hereas @*17pro,ides ser,ies at Layer : (the net+or layer. +e +ill

disuss it later) as +ell*This ena0les !R to oer hi#her per%or"ane and #reater

trans"ission eFieny than @*17. and "aes !R suita0le%or urrent &A' appliations. suh as LA' interonnetion*

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Issues +ith @*17

ey %eaturesinludeGall ontrol paets. in 0and si#nalin#"ultiple/in# o% ,irtual iruits at layer : layers 1 and : inlude o+ and error ontrol

hene ha,e onsidera0le o,erhead

At eah hop. LAPB e/han#es data and AK %ra"eAnd at eah node. state ta0les "aintained %or eah

V %or all9o+9error ontrol

not appropriate %or "odern di#ital syste"s +ith hi#h

relia0ility,erhead o% @*17 de#rades use o% hi#h data rates

lins*

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!ra"e Relay

desi#ned to eli"inate "ost @*17 o,erhead

has lar#e installed 0ase

ey dierenesG

all ontrol arried in separate lo#ial onnetion"ultiple/in# and s+ithin# at layer 1

no hop 0y hop error or o+ ontrol

hene end to end o+ and error ontrol (i% used)

are done 0y hi#her layera sin#le user data %ra"e is sent %ro" soure

to destination and hi#her layer AK sent 0a

<

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!ra"e Relay -e,ies

-e,ies attahed to a !ra"e Relay &A' %allinto the %ollo+in# t+o #eneral ate#oriesG-ata ter"inal e5uip"ent (-T=) -T=s #enerally are onsidered to 0e ter"inatin#

e5uip"ent %or a spei net+or and typially are

loated on the pre"ises o% a usto"er* =/a"ple o% -T= de,ies are ter"inals. personal

o"puters. routers. and 0rid#es*

-ata iruit$ter"inatin# e5uip"ent (-=) -=s are arrier$o+ned internet+orin# de,ies*

The purpose o% -= e5uip"ents is to pro,ide loin#and s+ithin# ser,ies in a net+or. +hih are thede,ies that atually trans"it data throu#h the &A'*

C

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!ra"e Relay -e,ies

(ont*)

E

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!ra"e Relay -e,ies

(ont*)

The onnetion 0et+een a -T= de,ie and a-= de,ie onsists o% 0oth a physial layero"ponent (L6)and a lin layer o"ponent(L1)*

The physial o"ponent denes the"ehanial. eletrial. %untional. andproedural speiations %or the onnetion0et+een the de,ies* ne o% the o""only

used physial layer inter%ae speiationsis the reo""ended standard (RS)$1:1*

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Protool Arhiteture

6D

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Arhitetureontrol PlaneSeparate lo#ial onnetion used %or ontrol

in%oAt -LL. LAP- used to pro,ide relia0le data lin

ontrol ser,ie

User PlaneHere LAP! (Lin Aess Proedure %or !ra"e

Mode Bearer Ser,ies) is usedore !untions o% LAP!G

!ra"e deli"itin#. ali#n"ent and transpareny %ra"e "u/ and de"u/ usin# addressin# eld ensure %ra"e is inte#ral nu"0er o% otets ensure %ra"e is neither too lon# nor short detetion o% trans"ission errors

on#estion ontrol %untions 66

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User -ata Trans%er

'o ontrol eld. +hih is nor"ally used %orGIdenti%y %ra"e type (data or ontrol)

Se5uene nu"0ers

I"pliationG

onnetion setup9teardo+n arried on separatehannel

annot do o+ and error ontrol

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Comparison of X.25 and FrameRelay Protocol Stacks

X.25 packet

level

LAPB

PHY layer

Implemented by

end system and

network

PHY layer

Implemented by

end system but

not network

PHY layer

Implemented by

end system but

not network

LAPF control

LAPF core

LAPF control

Implemented

by end system

and network

Implemented by

end system and

network

a! X.25 b! Frame relay c! Frame sw"tc#"n$

LAPF core

6:

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Ad,anta#es and

-isad,anta#es

lost lin 0y lin error and o+ ontrolinreased relia0ility "eans less an issue

strea"lined o""uniations proess

lo+er delay

hi#her throu#hput

%ra"e relay an 0e used %or aess speeds upto and o,er 1M0ps

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Appliations o% !ra"e

RelayTrans"ission o% Hi#h$Resolution raphisLar#e !ile Trans%er

Multiple/in# a lar#e #roup o% lo+$0itrate

appliations

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