managemetul traficului atm

8/10/2019 Managemetul Traficului ATM

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Managementul trafcului n reelele ATM

Scop Defnire QoS Defnire uncii CAC (Connection Admission Control and Virtual

Bandwidth) Explicare ra!c Shapin" Clase de ser#icii

Trafcul ATM i controlul congestiei$n unie de tipul de trafc controlul con"estiei de o%icei se re&ol#' princontrolul accesului proflarea trafcului i prioriti&area lui*

$nFig. 1 se pre&int' modul de ne"ociere al trafcului +n relaia cu clientulpentru a se e#ita con"estia*

ForwardConnectRequest

ATM Switch

PVC/SVC ConnectRequest

ATM Host

Desired QoS

BandwidthRequirements

Resource Check

Connection Admission

Control

TrafficDescriptor Parameters- ACR- PCR- SCR- BT- MCR

PerformanceParameters- CLR- CDV- CTD- CMR

oS

Control

Cell Stream

InformationFlow

TrafficShaping

AT Traffic Congestion ! Control

"enericCell Rate

Algorithm

#$ % #CBuffering

CLP

Traffic Po!icin"

TrafficShaping

#PC

Discardor Tag

Fig. 1 Negocierea parametrilor de trafc cu clientul pentru evitareacongestiei

Managementul Trafcului

Quality o Service,*-./ in ormaii pri#ind QoSUser !et"or# $ontractSetul de parametrii de trafc ne"ociai cu clientulFunciile %e control al trafcului

0etwor1 2esource 3ana"ementConnection Admission Control (CAC)


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4sa"e 5arameter Control (45C)Selecti#e Cell Discardin"

ra!c Shapin"Explicit 6orward Con"estion ,ndication (E6C,)

$lasele %e trafc ATM$lass 1 7 Defned to support constant %it rate connection oriented tra!cwhere end7to7end s8nchronisation is re9uired otherwise 1nown as Class Aper ormance re9uirements* his ser#ice should meet the currentre9uirements or per ormance compara%le to current di"ital pri#ate lineser#ices*$lass & 7 Defned to support #aria%le %it rate connection oriented tra!cwhere end7to7end s8nchronisation is re9uired otherwise 1nown as Class Bper ormance re9uirements* his ser#ice is intended or pac1eti&ed #ideoand #oice application li1e toda8:s #ideo con erencin" s8stems*$lass ' 7 Defned to support #aria%le %it rate connection oriented tra!cwhere end7to7end s8nchronisation is not re9uired otherwise 1nown asClass C per ormance re9uirements* his ser#ice is intended to supportconnection oriented data protocols such as 6rame 2ela8*$lass ( 7 Defned to support #aria%le %it rate connectionless tra!c whereend7to7end s8nchronisation is not re9uired otherwise 1nown as Class Dper ormance re9uirements* his ser#ice is intended to support connectionoriented data protocols such as S3DS*

$ategoriile %e trafc ATM$)* Constant Bit 2ate ( ra!c 5attern is deterministic ; cannot tolerate

cell dela8)+)* *T Varia%le Bit 2ate < 2eal ime ( ra!c 5attern is 1nown ; #aria%lecannot tolerate cell dela8)+)* !*T Varia%le Bit 2ate < 0on 2eal ime ( ra!c 5attern is 1nown ;#aria%le can tolerate moderate cell dela8)A)* A#aila%le Bit 2ate ( ra!c more #aria%le ; %urst8 than VB2 ; is dela8tolerant)U)* 4nspecifed Bit 2ate (0o "uarantee QoS)

,escriptorii %e trafcConstant Bit 2ate (CB2) 7 5ea1 Cell 2ate (5C2) i CDV *Varia%le Bit 2ate (VB2) 7 5ea1 ; Sustained Cell rates 3aximum Burst Si&ei CDV dac' este de tip (2 7VB2)A#aila%le Bit 2ate (AB2) 7 3inimum (3C2) i 5ea1 Cell 2ate (5C2)4nspecifed Bit 2ate (4B2) < doar 5ea1 Cell 2ate (5C2) onl8*

Usage -arameter $ontrol U-$/


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Ser&ice Categor' (CBR) #BR) ABR ! *BR+ aps to Qualit'of Ser&ice

Cell ,oss Ratio Cell Transfer Dela' Cell Dela' #ariation

Traffic Descriptors Include- $CR CR SCR BS CD#T

CBR .$CR) CD#T/#BR .$CR) SCR) CD#T) BS/

ABR .$CR) CR) CD#T/*BR ./

Traffic Descriptors Include- $CR CR SCR BS CD#T

CBR .$CR) CD#T/#BR .$CR) SCR) CD#T) BS/

ABR .$CR) CR) CD#T/*BR ./

Connection 0eededConnection 0eeded

ap Traffic T'pe to Ser&iceCategor'

ap Traffic T'pe to Ser&iceCategor'

Specif' Traffic Descriptors for theConnection

Specif' Traffic Descriptors for theConnection

Request the ConnectionRequest the Connection

Traffic Contract

Tra0c $ontract,nclude urm'torii parametrii=

-ea# $ell *ate -$*/Sustaina le $ell *ate S$*/)urst Tolerance )T/$ell ,elay +ariation Tolerance $,+T/

Traffic Descriptors

ATM SWITCH

$CRA

Ma%imum Ce!! t&rou"&put in a "i'en time(

)nce 'a!ue is reac&ed - ce!!s are discarded

Ma%imum Ce!! t&rou"&put in a "i'en time(

)nce 'a!ue is reac&ed - ce!!s are discarded

PCR

Connection rate conformin" to t&e a'era"e ATM ce!! rate(

#sefu! for VBR connections *+urst, +, nature

Connection rate conformin" to t&e a'era"e ATM ce!! rate(

#sefu! for VBR connections *+urst, +, natureSCR

Traffic parameter t&at ref!ects a time sca!e in w&ic&ce!! rate f!uctuations can +e to!erated(Traffic parameter t&at ref!ects a time sca!e in w&ic&ce!! rate f!uctuations can +e to!erated(BT

Defines t&e min/ma% amount of de!a, a connectioncan to!erate +etween t&e arri'a! of an, two ce!!sDefines t&e min/ma% amount of de!a, a connectioncan to!erate +etween t&e arri'a! of an, two ce!!sCDVT

2eneric $ell *ate Algorit3m4ea#y )uc#et Algorit3m

he >eneric Cell 2ate Al"orithm (>C2A) is a Continuous State ?ea18 Buc1et

al"orithm that defnes the relationships %etween the 5C2 and CDV andalso %etween SC2 and B* B8 doin" this the defnition o con ormance o


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the connection is defned and su%se9uentl8 en orced to pro#ide the statedthrou"hput and 9ualit8 o ser#ice* ,n short the lea18 %uc1et is the%u@erin" within the switch that permits the handlin" o %ursts o tra!ca%o#e a defned sustained rate* , 8ou loo1 at the %u@er as a %uc1et with ahole in the %ottom* he hole allows a maximum ow o water out o the%uc1et* , a %urst o water into the %uc1et does not exceed the capacit8 othe %uc1et all o the water will e#entuall8 ow to the destination* , thecapacit8 o the %uc1et is exceeded water is lost*

does C,$12 traffic conformto Sustained Cell Rate3

.es

o

.es o

Cell Stream

PCR

does traffic conformto peak cell rate3

SCR

setC,$12

0on4conforming cells ma' 5e discarded or tagged C,$16

Discardor ta"

Traffic $olicing ("CRA Algorithm+

Conformin" non-Conformin"

QoS -arameters$ell 4oss *atio $4*/ 0um'rul total de pachete pierdute raportat lanum'rul total de pachete trimise*$ell Trans er ,elay $T,/ is 9uoted to defne the maximum time that acell ta1es to transit a particular A 3 switch within the A 3 networ1* his isimportant to time7critical ser#ices usin" A 3*$ell ,elay +ariation $,+/ is 9uoted to defne the maximum chan"e inthe arri#al o cells due to clumpin" and spreadin" in A 3 switch %u@er9ueues o#er a particular connection* ,n a circuit emulation ser#ice themaintenance o a constant rate o cells o#er the connection is essential*Cell clumpin" could ma1e a C5E e9uipment %u@er o#er ow or con#ersel8the spreadin" o cells could cause a C5E %u@er to empt8*


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Traffic Control Functions

*sed to manage the flow of data into the network

ATM CPE

ATM Switch

Connection AdmissionControl (CAC+

Connection AdmissionControl (CAC+

*sage $arameter Control(*$C+

*sage $arameter Control(*$C+

Traffic ShapingTraffic Shaping

78plicit ForwardCongestion Indication

78plicit ForwardCongestion Indication

$onnection A%mission $ontrol i +irtual )an%"i%t3$onnection A%mission $ontrolVerifc' dac' noua conexiune nu #a a ecta trafcul din conexiunileexistente*

+irtual )an%"i%t3 he Virtual Bandwidth o a connection is the %andwidth which the switcheels it needs to allocate %ecause o some a@ectin" actor %ased on the%u@er stora"e installed at 9ueuin" points within the switch* Example 7 A 3Switch with Cells Switch 6a%ric* , we consider a ser#ice with 5ea1 Cell2ate o F/3%s a Sustained Cell 2ate o .3%Gs and a small 3aximum BurstSi&e (3BS) o - cells* he switch could address the connection asre9uirin" a Virtual Bandwidth which is at some #alue onl8 sli"htl8 "reaterthan the sustained 2ate* E*"* .*H3%Gs* , the same connection were to ha#ea lar"e 3aximum Burst Si&e (3BS) o sa8 F/ cells then the switch wouldha#e to reser#e a Virtual Bandwidth which is closer to the 5ea1 rate* e*"*H3%Gs*

)an%a virtual5 este detrminat' de mecanismul $A$ i are o #aloarecuprins' +ntre S$* i -$* cu o #aloare dependent' de )T.*


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Connection Admission Control

Ce!! Source 0

Ce!!destination

) C 1 C e

! ! R e

! a ,

C a r d

S!ot 0

Ce!! Source 2

S!ot 1

ATM Switc&

) C 1 C e

! ! R e

! a ,

C a r d

S!ot 02 Bott!enec3Bott!enec3

An e8isting $9$ #BR cross connect:In the left to right direction)

S*STAI0;2 1


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Explicit 6orward Con"estion ,ndication (E6C,) was created to allow thenetwor1 to in orm the C5E de#ices o impendin" or actual con"ested state*

,n ormaia E6C, este olosit' de client pentru a reduce #aloarea trafculuiinJectat +n reea pentru a se e#ita con"estiile* 0u este o%li"atoriu s' feimplementat' la ni#elul echipamentelor client*

!oti ying 78plicit For"ar% $ongestion 9n%ication he means o indicatin" the Explicit 6orward Con"estion is %8 settin" thesecond %it o a user cell 5a8load 8pe ,dentifer (5 ,) feld to a #alue o :F:*

6olosind aceast' in ormaie clientul poate ace aciuni corecti#e pentru areduce #alorile de trafc*

ATM CPE

.our wis&is m,

command

ATM Switch

Congestion Control (7FCI+

network informs C$7 de&ices of an impending or actualcongested state

C$7 de&ices then respond accordingl'

7FCI set the second 5it of a user cell $TI field to a &alue of ?6?

C$7 reduce the flow of data into the network

9e, s!ow downit:s "ettin" a !itt!e

too con"ested in &ere;;

Tra0c S3apingScop: AJustarea parametrilor la client pentru a se e#ita pierderea celulelorca urmare a apariiei con"estiei 5C2 SC2 B sau CDV *

QoS i AA4


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AT QoS

TimingRelationship

Bit Rate

Connectionode

Associated AA,

VBR-RT VBR-/RT #BR

CBR ABR

Required 0ot Required

Constant #aria5le

Connection4@riented Connectionless

AA, % AA, 6 AA, 9 AA, = AA, %

ServiceCategory

CBR

Rt-VBR

Nrt-VBR

ABR

UBR

QoS ClassNumber

1

2

1

1

2

3

1

1

QoS Parameter

CTD CLRCDV

STM-1 E3150uSec 10 -10

150uSec 10 -9

150uSec 10 -9

N/A 10 -7

N/A 10 -6

N/A 10 -5

N/A Low

N/A N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

250uSec

250uSec

2.5mSec

500uSec

500uSec

5mSec


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$)* Tra0c Management

PCR

CDVT

Traffic accepted +, #PC

Traffic )T a!!owed +, #PC

Pea3Ce!!Rate


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CDVTSustainedCe!! Rate

*SCR

Time

Ce!!

Rate

MBS12 Ce!!s

Ce!! DiscardTA$ or Discard

CDVTPea3

Ce!! Rate*PCR

#BR Traffic anagement

Multiple8are statistic578emplu !*T +)*

Statistical "ain In #BR Ser&ices

62 5%s AT Switch AT Switch

0

$eak62 5%sSust: 5%s

ATM 9ost

0

$eak62 5%sSust: 5%s

ATM 9ost

0$eak62 5%sSust: 5%s

ATM 9ost

0

$eak62 5%sSust: 5%s

ATM 9ost

0

$eak62 5%sSust: 5%s

7thernet*tili ationATM 9ost

0

7thernet*tili ation

ATM 9ost

$eak62 5%sSust: 5%s

A)* 78plicit *ate


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, an AB2 (E2) connection spans a lar"e num%er o A 3 switches the dela8in the control loop could cause cells to %e lost i an element in theconnection needs to tell a C5E to %ac17o@ in Allowed Cell 2ate due to areduction in a#aila%le %andwidth or con"estion* his pro%lem is addressed%8 AB2 (E2) VSGVD*

Phere VSGVD is a#aila%le the Switches e9uipped with this capa%ilit8 area%le to carr8 out an E2 Calculation on reception o the 623 cell and returna B23 cell with an E2 mar1in" immediatel8*

his reduces the len"th o the control loop in AB2 Explicit 2ate connectionsand the networ1 %ecomes more responsi#e to the Customer 5remisesE9uipment (C5E) as well as reducin" the li1elihood o networ1 con"estion*

VSGVD support is not re9uired in all o the A 3 switches in the connectionand this is illustrated in the adJacent dia"ram where three AB2 controlloops ha#e %een esta%lished*

he Alcatel multi7ser#ices A3 plat orms support AB2 Explicit 2ate withVSGVD support when the 3ulti7ser#ices ra!c Shapin" module is installedon A 3 Cell 2ela8 cards*

ABR Se"ment 0 ABR Se"ment 1ABR Se"ment 2

S

D

D

S

FRM f!ow

BRM f!ow

ABR 78plicit Rate #S%#D

VD

VDVS

VS VD

VDVS

VS


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managemetul traficului atm

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