frame relay
DESCRIPTION
It is a fine presentation on frame relays used for data communication.TRANSCRIPT
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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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