Cisco Press Cisco Catalyst QoS Quality of Service in Campus Networks pdf pdf

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• Table of Content s • I ndex

Ci sco Ca t al yst QoS: Q ual i ty of Se r vi ce in Ca m pus Ne tw or k s

By Mik e Flan nagan CCI E® No. 7651, Richar d Froom CCIE No. 5102, Kevin Tur ek CCI E No. 7284

Pub lish er: Cisco Press

Pub Dat e: Ju ne 06, 2 00 3

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En d- t o- end QoS deploy ment t ech niqu es f or Cisco Cat aly st ser ies sw it ches

Ex am ine v ar iou s QoS com pon en t s, including cong est ion m anagem en t , congest ion

av oidance, shaping , policing/ ad mission cont r ol, sign alin g, link eff iciency m ech anisms, an d classificat ion and m ark ing

Map specif ied class of ser vice ( CoS) v alu es t o v ar ious qu eu es and m ain t ain CoS v alues t hr ou gh t he u se of 8 02. 1q t ag ging on t he Cisco Cat alyst 290 0XL, 350 0XL and Cat aly st 40 00 and 29 48G/ 298 0G Cat OS Fam ily of Sw it ches

Lear n about classificat ion an d rew r it e capabilit ies and queue schedu lin g on t h e Cisco Cat aly st 5 000

I m plem ent ACLs, ACPs, ACEs, an d low - lat ency qu eu in g on t h e Cisco Cat aly st 2 950 and 35 50 Fam ily of Sw it ches

Under st and classif icat ion , policyin g, an d scheduling capab ilit ies of t he Cat alyst 400 0 and 45 00 I OS Fam ily of Sw it ches

Con figu re QoS in bot h Hy br id an d Nat iv e m ode on t h e Cat aly st 65 00 Family of Sw it ches

Ut ilize Layer 3 QoS t o classif y v ary ing levels of ser v ice w it h t h e Cat aly st 65 00 MSFC an d Flex w an

Under st and how t o app ly QoS in camp us n et w or k designs by exam inin g end - t o- end case st udies

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Qu alit y of ser vice ( QoS) is t he set of t echn iq ues designed t o m anag e net w or k r esour ces. QoS r ef ers t o t h e cap abilit y of a n et w or k t o pr ov id e bet t er serv ice t o select ed net w ork t raf fic ov er v ariou s LAN and WAN t echnologies. The p r im ar y goal of QoS is t o pr ov ide f low pr iorit y , in clud ing dedicat ed b andw idt h, cont r olled j it t er and lat ency ( r eq uired by som e int er act ive an d d elay -sen sit iv e t r aff ic) , and im pr oved loss ch aract er ist ics.

gener at ion of n et wor k ap plicat ion s such as real- t im e v oice com m unicat ions an d h igh- q ualit y v ideo deliver y, m ost of t he lit er at ur e av ailab le on t his fou ndat ion t echnolog y for cur r ent and fu t ur e bu sin ess ap plicat ion s focuses on I P QoS. Equally im por t ant is t he applicat ion of QoS in t he cam pus LAN env iron ment , w hich is p r im ar ily r espon sible f or d eliv er ing t r aff ic t o t he deskt op.

Cisco Cat alyst QoS is t he f ir st book t o con cent r at e ex clu siv ely on t he app licat ion of QoS in t h e cam pus env ir onm en t . This pr act ical g uide p rov ides y ou wit h insigh t int o t he operat ion of QoS on t he most popu lar and w idely deployed LAN devices: t he Cisco Cat alyst fam ily of swit ches.

Lev er agin g t he aut h or s' ex t en siv e ex pert ise at Cisco in t he supp ort of Cisco Cat aly st sw it ches and QoS deploy ment , t he b ook pr esent s QoS f r om t he cam pu s LAN perspect ive. I t ex plains w hy QoS is essent ial in t his env ir onm en t in or der t o ach iev e a m or e det er min ist ic b eh avior f or t r aff ic w hen imp lem ent ing v oice, v ideo, or ot h er delay - sensit iv e ap plicat ion s. Thr ough ar chit ect u r al ov er v iew s, conf igur at ion ex am ples, real- w or ld d ep loym ent case st ud ies, an d sum m ar ies of com mon pit f alls, you w ill un derst and h ow QoS operat es, t h e diff erent comp onent s in volv ed in m akin g QoS possible, and how QoS can be im plem en t ed on t he var ious Cisco Cat alyst plat for m s t o en able t r uly successfu l end- t o- end QoS app licat ions.

This b ook is par t of t he Net w ork ing Technology Ser ies fr om Cisco Pr ess, w h ich off ers n et wor k ing pr of essionals v alu able inf orm at ion for con st ru ct in g ef ficien t net w or k s, und er st andin g n ew

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Cha pter 9. QoS Support on t he Cat aly st 6 50 0 MSFC and Flex WAN

MSFC an d Flex WAN Arch it ect ur al Overv iew

QoS Suppor t on t he MSFC and Flex WAN

Classif icat io n

Mar kin g

Policing and Shapin g

Con gest ion Managem en t an d Schedu lin g

Con gest ion Av oidance

Sum m ar y

Cha pter 10 . End- to -En d QoS Ca se Stu dies

Cha pter Prerequisit es an d Mat er ial Present at ion

Mu ltiplat f orm Cam pus Net work Design and Topology

Access Lay er Swit ches

Dist ribut ion Lay er

Core Lay er

Sum m ar y

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Copyright

Cop yr igh t © 2 003 Cisco Sy st em s, I nc.

Cisco Pr ess log o is a t rad em ar k of Cisco Sy st em s, I nc.

Pub lished by : Cisco Pr ess

20 1 W est 103 rd St r eet I ndian apolis, I N 462 90 USA

All r ight s reserv ed. No par t of t h is book m ay b e repr od uced or t r ansm it t ed in an y for m or b y any m ean s, elect r onic or m ech anical, inclu ding ph ot ocopy in g, r ecor d in g, or by any in for m at ion st or age and r et r iev al syst em , w it hou t w r it t en p er m ission fr om t h e pu blish er , ex cept for t he inclusion of b rief qu ot at ions in a r eview .

Pr int ed in t h e Un it ed St at es of Am erica 1 2 3 4 5 6 7 8 9 0

Lib rar y of Con gr ess Cat aloging- in - Publicat ion Num ber: 20 021 091 66

Warning and Disclaimer

This b ook is desig ned t o pr ov ide inf or mat ion ab out qu alit y of ser v ice ( QoS) f or t he Cisco Cat aly st sw it ch plat f or m. Ev er y eff or t h as been m ade t o m ak e t his b ook as comp let e and as accu rat e as possible, but no w arr ant y or fit n ess is im plied.

The in for m at ion is p r ovided on an " as is" basis. The au t hor s, Cisco Pr ess, and Cisco Sy st em s, I nc. shall h ave n eit h er liab ilit y n or r espon sib ilit y t o any person or ent it y w it h r espect t o any loss or d amag es arising fr om t h e inf orm at ion cont ained in t h is book or fr om t h e use of t he d iscs or pr ogr am s t h at m ay accomp any it .

The op inions ex pr essed in t his b ook belong t o t he aut hor and ar e not necessar ily t hose of Cisco Sy st em s, I nc.

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Trademark Acknowledgments

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Dedications

Mike Flannagan :

I w ould like t o d ed icat e t h is book t o Ann e. Th ank y ou for y our loving sup por t an d

encour agem en t d ur in g t he seem ing ly en dless n ig ht s an d weekend s spent on t his pr oject .

Richar d Fr oom :

I w ould like t o d ed icat e t h is book t o m y w ife Elizab et h f or her sup por t , un derst an ding, and pat ience w hile I w as aut hor ing t he book . I w ould also like t o t h ank Elizabet h for her cooperat ion and assist an ce in r eview in g my mat er ial.

Kevin Tur ek :

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About the Authors

Mi k e Fla nna ga n, CCI E N o. 7 6 5 1, is a m anager in t he High Tou ch Technical Sup por t ( HTTS) gr oup at Cisco Syst em s in Resear ch Tr iang le Park , Nor t h Car olina. Mik e j oin ed Cisco in 200 0 as a net w or k consult ing engineer in t he Cisco Ad van ced Ser v ices g rou p, w her e he led t he cr eat ion and deploy m en t of t h e QoS Vir t u al Team. As a m em ber of t he QoS Vir t ual Team , Mik e w as inv olved w it h t he dev elop ment of new QoS feat u res f or Cisco I OS an d developed QoS st r at egies and im plement at ion g uidelin es for som e of t he lar g est Cisco en t er pr ise cust om er s. Mik e t each es QoS classes and lead s desig n clinics for in t ern al and ext er nal audiences and is t he au t hor of

Adm inist er in g Cisco QoS f or I P Net w ork s, p ublished b y Sy ngr ess.

Ri ch ar d Fr oom , CCI E N o. 5 1 0 2, is a soft w ar e and QA en gineer for t he Financial Test Lab at Cisco Sy st em s in Resear ch Tr iang le Park . Rich ard j oin ed Cisco in 19 98 as a cust om er supp ort engineer in t he Cisco Technical Assist an ce Or ganizat ion. Rich ar d, as a cust om er sup por t

engineer , ser v ed as a supp ort engineer t r oub leshoot ing cust om ers' net w or ks and as a t echn ical t eam lead. Being inv olv ed w it h Cat alyst pr oduct field t r ials, Richar d h as been cr ucial in dr ivin g t r oub leshoot ing capab ilit ies of Cat aly st pr odu ct s and soft w ar e. Cur r ent ly , Richar d is w ork ing w it h t he Cisco st or ag e net w ork ing pr od uct s. Richar d ear ned his bachelor of science d eg ree in

com put er eng in eer ing at Clem son Univ ersit y .

Ke v in Ture k , CCI E N o. 7 2 8 4, is cur r ent ly w or king as a net w or k consult ing engineer in t he Cisco Fed er al Su ppor t Pr ogr am in Resear ch Tr iangle Par k . He cur r en t ly supp ort s som e of t h e Cisco Depar t m ent of Def ense cust omer s. Kevin is also a m em ber of t he in t er n al Cisco QoS vir t ual t eam , supp ort in g b ot h in t ern al Cisco engin eer s and ext er nal Cisco cu st om er s w it h QoS

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About the Technical Reviewers

Ja son Corn et t is a cust om er su ppor t en gineer at Cisco Sy st ems, w h er e he is a t echnical leader for t he LAN Sw it ching t eam in Resear ch Tr iangle Par k . Jason joined Cisco in 199 9 an d h as a t ot al of fiv e y ear s of n et wor k ing ex per ien ce. He holds a diplom a in bu siness t echnology in for m at ion com mu nicat ion s syst em s fr om St . Law r en ce Colleg e. Prev iously Jason w as a net w or k su ppor t specialist w it h a n et wor k m anag em ent comp any .

La ur en L. D ygow sk i, CCI E N o. 7 0 6 8, is a sen ior net w ork en gineer at a maj or f inancial inst it ut ion and has mor e t han eigh t y ear s of net w ork ing exp er ience. He holds a bachelor of science degr ee in com p ut er science f rom Tex as Tech Univ er sit y and a M. S.B. A. f r om Bost on Univer sit y. Prev iou sly , Laur en w as a net w or k m anager w it h t he Unit ed St at es Mar ine Cor ps and MCI . He resides w it h h is w ife and t h ree sons in Ch ar lot t e, Nort h Car olina.

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Acknowledgments

Richar d w ould lik e t o ack now ledge his co- aut h ors f or ask in g him t o wor k on t h is pr oject an d t heir eff or t s on t heir m at erial. Fur t her m ore, Rich ard w ould like t o ackn ow led ge Balaji

Sivasu br aman ian f or his aid and ou t st an ding r eview s of t ech nical cont ent pert ain in g t o t h e Cat aly st 4 000 Family of sw it ches.

Mik e w ould lik e t o ackn owledg e Dav e Knut h an d h is ot her f riend s in Net w or k Op t im izat ion Sup por t f or t heir sup por t . Mik e w ould especially lik e t o t hank Chr is Cam plejoh n, Nim ish Desai, and Zahoor Khan for ask ing t he t ough qu est ions t hat alw ay s helped m e lear n. Thank s t o t he m em b er s of t h e AS QoS v ir t u al t eam for t heir out st an ding t eamw or k an d t echnical ex pert ise in supp ort of our cu st om er s. Mike wou ld especially lik e t o r ecog nize Richar d Wat t s f or his su ppor t of and cont r ibut ion s t o t he t eam . Finally, t hank s t o m y new t eam in Cisco' s HTTS g r oup for an excit ing new op por t un it y t o lear n.

Kevin w ould lik e t o per son ally t hank h is co- aut hor s f or agr eein g t o do t his b ook, and for t heir m ot ivat ion , pr of essionalism , an d ex per t ise, w hich en su r ed it s t im ely com plet ion w it hout sacr if icing qu alit y . Th ank s esp ecially t o Rich ard f or his f ocu s and accept ance of an addit ional load, d espit e his alr ead y busy schedule.

All t h e aut hor s w ou ld lik e t o t hank Jef f Raym on d f or his t im e an d recomm end at ions t h at

cont r ibut ed t o t he t echnical accur acy and qualit y of t h e cont ent pert ain ing t o t h e Cat aly st 65 00 Family of sw it ches.

A b ig t hank y ou goes t o t he t eam at Cisco Pr ess, esp ecially Br et t Bar t ow f or his ov erall su ppor t of t his p r oject and Ch rist oph er Cleveland and Jennif er Fost er f or t heir sugg est ions and in put . We w ould like t o giv e special t hank s t o our r eview t eam of Jason , Laur en, and Balaj i f or t heir

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Icons Used in This Book

Thr oug hout t his b ook, you w ill see t he f ollow ing icons u sed for net w ork ing dev ices:

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Command Syntax Conventions

The con vent ions used t o pr esent comm an d sy nt ax in t his b ook ar e t he sam e conv ent ions u sed in t he Cisco I OS Sof t w are Com man d Ref erence. The Com man d Ref erence d escrib es t hese

conv en t ions as f ollows:

Vert ical b ars ( | ) separ at e alt er nat iv e, m u t ually exclusive elem en t s.

Squ are br ack et s [ ] ind icat e op t ional element s.

Br aces { } indicat e a requ ired choice.

Br aces w it hin br ack et s [ { } ] in dicat e a r equir ed choice w it hin an opt ional elem en t .

Bold fa ce in dicat es com m ands and key w ord s t hat ar e ent er ed lit er ally as show n . I n act u al conf ig ur at ion ex am ples and out p ut ( not general com m and syn t ax ) , boldf ace indicat es com man ds t h at ar e m anu ally in put by t h e user ( such as a show com m and) .

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Introduction

This b ook is int ended for all net w or k en gineers wh o d eal wit h Cat aly st sw it ches and specif ically for t hose look in g for a deep er und er st and in g of t he QoS cap abilit ies of t hose sw it ches. I n add it ion , any net w ork eng ineer responsible f or end- t o- en d QoS policies in a Cisco net w ork will fin d, eit her now or in t he n ear fut u r e, t he need t o t h orou ghly u nder st and Cat aly st QoS.

Besid es t he conf ig ur at ion sy nt ax in for m at ion p r ovided in t his book , t h e aut h ors hav e m ade ever y at t em pt t o d iscuss com mon p ract ices and pr ovid e case st u dies. Th is t r eat m ent of t he sub ject m at t er pr ov ides r ead er s w it h m ore t han ju st comm an ds f or con figu r in g QoS on Cat aly st

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Motivation for This Book

Aft er cou nt less h our s spent t r ying t o locat e var ious p ieces of infor m at ion for ou r cust om er s, t h e aut h or s realized t h at t here w as not a good Cat aly st QoS book an yw h er e t o be f ound . Rat h er t han cont inu e t o an sw er t h e same quest ions, w e decid ed t o pub lish our collect ion of t h e most

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Goal of This Book

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Prerequisites

Alt hou gh any one can read t his b ook, t he au t hor s assu m e reader u nder st anding of som e

fu ndam ent al net w ork ing concept s discussed in t his book . I f y ou do n ot h ave b asic kn owledg e in t he follow in g areas, y ou migh t h ave t rou ble un derst an ding cer t ain exam ples and concept s pr esent ed in t his t ex t :

Cisco I OS—Basic syn t ax

Cisco Cat aly st OS ( Cat OS) —Basic sy nt ax

Access- con t r ol list ( ACL) conf ig ur at ion

Vir t ual LANs ( VLANs)

I P ad dr essing

Rou t ing pr ot ocols—Basic syn t ax and concept s

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and Cisco I OS.

Cha pt e r 9, QoS Su ppor t on t he Ca t al y st 6 5 0 0 M SFC an d Fl ex W AN— This chapt er discusses t h e QoS cap abilit ies of t h e Flex WAN and MSFC in t he Cat aly st 6 500 . The chap t er show s how t he FlexWAN and MSFC ex t end t he Cat alyst 650 0's QoS capab ilit ies t o t he MAN and WAN. Exam p les d em onst r at e conf igur ing QoS using t he MQC av ailable in Cisco I OS.

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Part I: Fundamental QoS Concepts

Ch apt er 1 Qualit y of Serv ice: An Ov er v iew

Ch apt er 2 End- t o- End QoS: Qualit y of Ser vice at Lay er 3 and Lay er 2

Ch apt er 3 Over v iew of QoS Sup por t on Cat aly st Plat f or ms and Ex plor ing QoS on t h e Cat aly st 2 900XL, 35 00XL, and Cat aly st 4 000 Cat OS Fam ily of Sw it ches

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Chapter 1. Quality of Service: An

Overview

The con st an t ly changin g n eeds of net w ork s h ave cr eat ed a deman d for sensit ive ap plicat ion s ( such as v oice ov er I P ( VoI P) and v id eo confer encin g over I P) , an d n et wor k s ar e being asked t o supp ort incr easing ly mission - crit ical d at a t r aff ic. Pr ovidin g p redict able ser vice levels for all of t hese dif fer en t t y pes of t r aff ic has becom e an im por t ant t ask for n et wor k ad m in ist r at or s. Bein g able t o pr ov ide pr edict able and d if fer en t iat ed serv ice lev els is k ey t o ensur ing t hat all app licat ion t r aff ic r eceives t h e t r eat m ent t hat it r equir es t o f un ct ion pr oper ly.

This chap t er cov er s sev eral asp ect s of qu alit y of ser v ice ( QoS) an d d iscusses how t o pr ov ide QoS in Cisco net w ork s. Specifically , t h is chapt er cov er s t h e follow ing t opics:

Under st anding QoS

Deploy ing QoS in t he WAN/ LAN: Hig h- Lev el Ov er v iew

Cisco AVVI D ( Ar chit ect ur e for Voice, Video, an d I nt eg rat ed Dat a)

Ov erv iew of I nt egr at ed Ser v ices and Dif fer en t iat ed Ser vices

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Understanding QoS

The f ollow in g sect ion d ef ines QoS in t er m s of m easur able char act erist ics. I t is im por t ant , how ev er , t o r ecogn ize t hat fu lly u nder st anding QoS r eq uir es m or e t h an a defin it ion . To t ru ly un derst an d QoS, y ou m ust und er st and t h e con cept of m anaged un fair ness, t he necessit y for pr edict abilit y, and t he g oals of QoS. I n addit ion t o a def in it ion of QoS in measur able t er m s, t he follow ing sect ion exp lain s each of t hese t hin gs, t o p r ovide you w it h a w ell- r ou nded and pr act ical defin it ion of QoS

Definition of QoS

QoS is defined in sev er al w ay s, and t he com bin at ion of all of t hese d ef init ions is r eally t he b est defin it ion of all. A t echn ical definit ion is t hat QoS is a set of t ech niqu es t o m anag e band w id t h, delay , jit t er , and p ack et s loss for f low s in a net w or k. The pu r pose of ev ery QoS m echanism is t o inf lu en ce at least one of t hese four ch aract er ist ics and , in som e cases, all four of t hese

Bandwidth

Band widt h it self is defined as t he rat ed t hr oug hpu t capacit y of a giv en net w or k m ed ium or pr ot ocol. I n t he case of QoS, b andw idt h m or e specif ically m eans t he allocat ion of band w id t h, because QoS does not hav e t he cap abilit y t o inf luence t he act u al capacit y of any g iv en lin k. That is t o say t hat no QoS m ech anism act ually cr eat es add it ion al ban dw idt h, rat her QoS m echanism s enable t h e adm inist r at or t o mor e eff icient ly u t ilize t he ex ist ing b andw idt h . Band wid t h is

som et im es also r ef er r ed t o as t hr ou ghput.

Delay

Delay h as sev er al possib le m ean in gs, bu t w hen discussing QoS, pr ocessin g d elay is t he t im e bet w een w hen a d ev ice receiv es a f r ame and w hen t hat f r am e is for w ar ded ou t of t h e dest inat ion por t , ser ializat ion d elay is t he t im e t hat it t ake t o act ually t r ansm it a packet or fr am e, and end-t o- end delay is t he t ot al delay t hat a p ack et ex periences fr om sour ce t o dest in at ion.

Jitter

Jit t er is t he dif fer en ce bet w een int erp ack et ar r ival and depar t ur e—t hat is, t he v ar iat ion in delay fr om one pack et t o anot her .

Packet Loss

Packet loss is just losing pack et s along t he f or w ard in g pat h. Pack et loss r esu lt s fr om m any causes, such as b uff er con gest ion , line er ror s, or ev en QoS m echan ism s t h at in t en t ionally dr op pack et s.

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err or occur s, all im plement at ion s of t he diff er ent iat ed ser v ices ar ch it ect u re sh ould p r ovide t he sam e t r eat m ent t o each packet of t he sam e t y pe w hen t hose pack et s pass t hr ou gh a giv en int er face. I n Figur e 1- 1, m ult ip le packet s ar e sent f r om Bob t o t h e w eb serv er , m ark ed wit h I P pr ecedence 2 .

Figu r e 1 - 1 . M ul t ip le Pack et s fr om Bob A r e Se nt t o t h e W eb Se r ve r

M a r ke d w i t h I P Pr ecede n ce 2

I n t his exam p le, b ecause all HTTP pack et s fr om Bob ar e m ark ed w it h I P p reced en ce 2, an d t he policy on rou t er A's ser ial int er face is t o classif y all HTTP packet s w it h I P pr eced en ce 2 int o t h e sam e class, y ou can assu m e t hat t hese packet s w ill all r eceiv e t he sam e t r eat m en t . Because all pack et s of t he sam e t y pe ar e goin g t o be t reat ed t he sam e as t h ey egr ess t hat int er face, it 's easy t o pr ed ict t he t reat m ent t hat t he nex t HTTP pack et fr om Bob w ill r eceive. Th is is a sim plified exam ple of t he ov er all g oal of QoS: pr ovid in g pr ed ict ab le ser vice levels t o packet s as t hey m ove t hr ou gh a net w or k .

I t is v er y imp ort ant t o be able t o p r ed ict t he b andw idt h , delay , jit t er , and p ack et loss t hat can be exp ect ed as pack et s of a giv en f low t r av er se m ult iple hop s in a net w or k . Voice packet s, f or exam ple, m ust not hav e a on e- w ay d elay g reat er t h an 1 50 m s and ar e v er y int oler ant of jit t er . Bein g able t o say w it h conf id en ce t hat voice pack et s w ill ex per ien ce low lat en cy and jit t er at each hop along a given pat h is cr it ical w h en pr ov ision in g I P t eleph ony solut ions.