Table Of Contentmh TIMELY. PRACTICAL. RELIABLE.
Understanding
RIP, OSPF,
BGP, MPLS,
CR-LDP, and
RSVP-TE
Stephen A. Thomas
Digitized by the Internet Archive
in 2022 with funding from
Kahle/Austin Foundation
https://archive.org/details/ipswitchingroutiO0O00thom
IP Switching and
Routing Essentials
Understanding RIP, OSPF, BGP,
MPLS, CR-LDP, and RSVP-TE
Stephen A. Thomas
Wiley Computer Publishing
John Wiley & Sons, Inc.
New York e Chichester e Weinheim e Brisbane e Singapore e Toronto
Publisher: Robert Ipsen
Editor: Margaret Eldridge
Managing Editor: Penny Linskey
Text Design & Composition: Stephen Thomas
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Copyright © 2002 by Stephen A. Thomas. All rights reserved.
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Published simultaneously in Canada.
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Library of Congress Cataloging-in-Publication Data:
Thomas, Stephen A., 1962-
IP switching and routing essentials : understanding RIP, OSPF, BGP, MPLS, CR-
Lpp, and rsvp-TE/ Stephen A. Thomas.
p. cm.
Includes index.
ISBN 0-471-03466-5 (pbk. : alk. paper)
1. Routers (Computer networks). 2. Telecommunication—Switching systems. 3.
Computer network protocols. 1. Title.
TK5101.543.T48 2001
004.6—dc21 2001046810
CONTENTS
Chapter 1 ° Introduction sedecesceececscsccccsesvescncvocesactsecceecoesserostoccsceecoseseseccocescoucscoul
Oreanizing witht Daversand Flierarchies «cists. naiyu tires aerate 3
LEAVES rere eres ences Lee cbiisatbscusseteaannvas Seteieds aatf eaaenm esass cRaatv Meesern aa s3
RTOALCS IN S res ene ee eres ee ets ast catean cd a ova ggg cece rei ee Oe ri
1 eed WP SNPs elW oke S ee ce SRB en Weg Ret 8
Mite iterate oe GOCOCOIS tcp abes seis nnscawececdeenes eee 9
Lestaicot SUDINELOVOCIRSM ATIC UNCCIMEES c.sci.5scctacsnsconetc couereutes ccontcewssseenaue naeacste e 10
LOSE seri ctels CICSR ene tees chs s ccd cas Sad sec Sock conn URS SRACE 12
GrienNICATON 9 CTV ICOSietee co orto ce aon e dc cbecdvtseccteeee ciokesteer 13
ep TS SETHS S OAS TS aR PIR BS UE Ne ire ay. SEQ EN Fiance 14
Conmect©i moemnte d LOCMVELy cr. bs a5es-cacstse coeds svete arasseen ccreemnee ne Oe 15
Sepa eT NRT es sate PARE ROe Re PEC Ne
USaEiiSg0 ) ala Ua( 0F SIS01 8:A ee Beg RO Pe RO eR GFR Pca Cece 19
Theil m N CEWVOTICOA CL ESSES Sc e5s ovcidisatbedati taste ee ae 19
Types of Addresses ..........ccccscsssssesesesseeenstenensenesessssessseeesessenseseseseseenenesesens 20
TP WddreseePocnvarce 16. NE at cee A EG Ae neds renee a1
SUTINL Y <2 u2 sate Meet enonensonscaneceasrsacensadscerenesnsnsnencecenenescvonsnanncnsnsnsanebanasdenezenveern s2 4
Chapter 2: IP—The Internet Protocol .......s.seceresrersrerersesesercsesseseessessssnssssees ZO
he Role Of thesnternet Protocol .cssec.ceos.ss0ncceovacsencssaseosess0esk=eSehaasonadtagaveransouressane 25
EUW ie s1B D aea cecet ara «eels an sac an anvannen on onenaesnensvedadeche=t-“ttatrenueaneasstnduetenvaeze 28
Vyscetc dew ie sosl ose Bians buas eca dernurp se0 074 tapes Sop eereneracae ances2 8
Header eet ins.. n.scr9:grecscz0s0-22-nasneisustanntiensuchsadn<nsess+4entssesstcncaneasecnntecnssens 28
IP Switching and Routing Essentials
IDitiere mtiated Service 5.5 deccdsevs wish ose) pau vasorseseareeenac econ nee eee 29
explicre @ongestion Notification .2...4ses0.s.asuesustuescsusscarcemmerucesaseeeaIntsetactaa 30
NPA syA C COMES TESOL a aad dev sovio sNTUed ayer eenan see oaeacana dams aes amen Sse ane tae 31
PPOG AIMEAL L OM sc ehte cor auho batacsnosiiurnsase xcroal taimee uecanu awsaeenaseteea:r aeo ui
Hi (6)o pel0 F)1 01 epee oe PBR etme ROE NT See ets heno e e rd pry ON mr reer Rn 34
INGO TCELEE eo aise wisn inate LN eRe Sea ee welt areca a aes 35
Preadet Checks uiiin se. iocs cotaeke veteeee ere isaland cusn cwedaape cesenees 36
Tan(a a0 Sak MORI AS has ARR UNE, SBN er Roper G8 ao
TTPO) EU 106 cacao cae stat secu naires ca ene nee ee ee Ae nate ce 38
SOUEGE ROU cet oceros see ncsnrte sees aea nts try wasae wekcut ste. sessnesiees Reo eee 40
Recordings Routes and 7)1 miesita eres neesreep esc .e e ee4 3
Internet: Control Message Protocolwethea reeetee neaee 46
ICIVMIE Message: Boritiatrsscuet gees tors eacenncc cde ee ee ee eee 47
Discovering Routers ee REC l es acs arnevia es cia ee eaten en eek eer er eee me 49
Reporting Ir rors ts lire cet ecttt certs c iota a ee eee 55
Drgnosing Network Devel Proplems ......c-. neers teen earn ee 57
Internet Group Manapenvent lero tocallee. ie et ne ee 61
DW LG O10 Bic Ssutoaccoe deste amare noes as sacs Se oa ee Se 62
Streamlined Fléader. Portia ts 1e.cecssacion tc teeter es ckcect ces eeee ee 62
SLOW BSAH e| teat Sea bocoans eereces taceae see vss cc ai RTI aeee e 62
128-Bit NetworeAddressess a wien hn eee eee 63
Klimmation of the header @hecksuni 2 ee 63
Fragmentation Only by source [10st ..... 1 emeticcoc. e.e.e 63
Extension Pleadkers irrrccrttsrecs canes cclsscelc ne eeee en 63
Braabeaun Security sacar cebtevonay a eeccosses i scaneses serene eos cerst ee 64
OAUTH 08116 7 ORR ERP ict ERROR yy eR Ronn ns 64
Chapter 3: Transport Protocols — An Overview of TCP and UDP............... 65
Distinguishing Applications cc: .15..:2..ccs sta mem eaneemtenn eoetskacsccsceeee ce eee 66
POLS seec cansondvendo gig Maduentncettsnaasancs yd ee ah RE a 66
BOCESU S OG lec Cae tins s oceans vnc Rae oR MRR oc coca cS 69
Datagram Delivery ierereccs scien: ee eet cee ee 69
User Datagram iretocol «. <....2.05.seaeeeermeneeonscoes ootoeeeew 71
The Transmission’ Contrel/ Protocol... samen ee ee 74
Contents
The Need for Aivairspart.Protocol scence anasowss sealant 76
Connection-Oriented Operationcrnee ccnt .un.a ceaet eaece s 79
Se Paa cnershormatinn Ac: fc... 0. ke ew ke oe Nee ae aoe 88
MONG 1 Ce StateaVi ac hie Men cetis soe hasssciaee cde eid ee 93
SON AINANAIYNV esO ARS scat sia sacaovenvesnicnd neoee AUN ARON EN OR 96
Chapter 4: Link State Routing and OSPF ...........csccssccssscssecesscsssscesessnsees 97.
|S ET ReV ERA RCEU T eee ee are Ree en Ook dN a ae 98
IVICCRAN GN BINODE DIOL S a3 iscass s5aehe. ccaeet cans gueteca corsa evar eee OR ee a 09
State CITE latE MALIO N os 05s cz, casorsccaseedee neaneco reeeenss 100
CES ANAS SEN YC eRaN e ae 0 103
INEST MG TAINOO S onan Joss accsvowaiceustORcete uaccesh MMsee stesst aset ceetna ace1 05
CSP Heard etree © re SRIZ AIO 0.205 05s tonesvenicanssnscsasteessepans etUemecau sees : 107
WATERCO HOM CMS tOS UCIING ya tcceannnys ss.y dgresssasinevivesosSsaest esgusaiaenns ptasetiareeeeteanson e 108
A A PN AE 1 Sc nn Lesa da'esc adiesaddentc ORO Roe ie 109
IS 8 Se CS Oe EY ae Ce eee ae rT ct on faye oe 111
SEL ses Pe el Oe ae nnn eM ET eer sR tien een Neer slay
INU SOOO VeA RES lysis cea s sawing nas nn cnnn shsvusesiabtarcsinttease vearnee tee s1 14
Special Networks ne cstrcesarartsct.cccccasserssavtesxchsessone vvsrestaspu-casdvesnvdasbeyasvolrerdteen rsb.en es 114
Broadcast NGRWOrkS seiko ooco css SEI hae ie A ee eee 114
Nonbroadcast Multi-Acccess Net works :oc..ccc...0seccssiectecesestcccccssdeaesstouvessone’ 118
Point-to- Multipoint Networks 2.200 5.20..02:cs0ncaccanncennneoeunateteneeescacentaemacnteeys 119
Denna ane tore cies yea rece dese cere shee leet eee a eee 120
DA alcicast IRG ui ceca caer esnsnsnnncsneaonnenrven da nnedemnancqigansmnsuan terse omesasctss 121
OSPF Message Format...............sssssssssesssssssesssssessesecesesensesssssecsssecesesevessensseesens 125
Authenticating OSPF Messages ........:cccsececeesesesereeseseseeneeseseneeessenenesseees 127,
Meeting Neighbors ..........ccsesescssesssesseseseeeseseeneneneeseenessenseneseeneneensneeesneneeeneneeeas 131
Advertising Link States.............sssssssssssssseeasssssenenceseseesenssesesneneesssensnenesessenenens 133
PLEO NaI MPR wee ees ce occas he sa daa cedsccsss sans cooetasdaeacetemredtuastaress s1 36
ING EWG Tl es Ree et a ENED mao cietesaccacccecentretacenenamessecerersesr s1 38
Summary Links ..0.......:....cssssssssssscsssscecsnsscecscsesssessesesenensenesessenscesessenessesees 140
Boxter arye s rer errr ae anoes b ae dde daca ca Seces ccotonessonnnsanceewesencenss 142
Group Membership Advertisements........:.scecsesessssetrerrereseseseseseesessensees 146
NSSA Advertisements ...:::c.cccccccssosssecosssscsecccsonssccrsssscseensoesonnesssasebsoceosaces 147
Opaque Advertisements ............c.ccseccsossssssecsessessnsennessnsersssensonternseateeasertes 148
vi IP Switching and Routing Essentials
Reliable: Plog gsc. 2252. cecsck ontseasacsasunscov dere Nee oanee ote ee ented eee eemneetn eee Enea 149
Updating: Nero liborssa cre sie cotct oto ck or erent rae reer ner ene rena rea tee 150
SULIMVIANY segtsegsccnut eoes ce cavenghonen oonbrendinevtonvessvere Seuuouses tes uaraesracaiaghars Seah a sees econ 154
Chapter 5: Distance Vector Routing and RIP...........sccsssrrcceesrreeessereeeens 157
Distance Vector Rowtitty sscssnceeoe ntee seec ceotsasd otme 157
Mig meted, Updates icso ccssscvescneesteesdasRvaveehcceasaeaecntw aserstnesiesea rece necereonaaaenoeae e 162
Counting to Infinity sce wc ee se aoe ke ara ee 164
oy i gl eye 720 ocr PRR EOE P ER nor bur PRP ER EMR he 167
FIP? Meesa esP O rnin tres cay Wey occas oo nevcsd oo sen at uate: oarensubi/oHosccadouavagsencaeeeeeee 170
FOEPPATIERETICHCALION Stavuwstrassdes wna ecoee eee ona. © aed aac oc. sate cen eee eee 172
NCA FESSIMNG TELE AIVICECACC G geen re ee ee eco ane eee 176
1a aati alge eee ne RS Sot ery net tetris EL ON SCR Redes A Rc set 176
|B Blairs ev Ea ODF asd)l n) 2b oe MRR RE ROR CF 9 OF AERC ee OTA Ds CO RUN SA ees 178
inaitedi Networks Diane tera: sacecties sonsnc x covic odie dicc- cube ca dawess conancevecariesteeens 178
Responsiveness £0 NetWork. Gal ges: cc c5casts.nrecsc ucskcenattesrarceet cearrn s 179
Wlulticast ROWE G sti cee eee ere ee ae apnea See 180
SURIB o sel aacareds elt cat Aiea Ueno Menon caate th kes Meron at /ctys ct ne ee 180
Chapter 6: Path Vector Routing and BGP...............ssssssccccccessesessssssssscsesesens 181
Tinplementing: Policy: so.ccwmensneeeeeee aeseea ceeaWmo ruseacen cen 183
Influencing Routing, |a topiiation....s.ccsets ccent eeaes enedeexee 185
Patin Vector, ROU ting. juccscasuet ot ececeonvic ons nsp-ductsa eacenene eae oeartnansiicac See ee 187
Distance Vector Routing without Distance access :.cdacesoeruo uteete 188
Counting to Ta fiiey reece cn s.n31ss.2 sas saqac ee eee Ae Sc atn tess ene 191
RoutenAreg tera ti Cine seteesy sien << Gases honey, Ramee ees <n. sca eee 192
Normal: B GPO peratieins seer crsacscsncs.v-otics.c acca teegmtemeere ins staccato eee 194
heiMDS. Stonatures® ption tor TCP ccxeccoedesw <:oaccqcecocasaeet eeeee ee e 195
BGP within an Autonomous Systemt...z...::...cn. meeteenere 196
Titterior’ BGP sso ai dads vestses cual en eee 197
Router Reflectors ces sass cesses <nesanhecneon ee eae Ee. codec 200
Coonidefr eit eor is areemire sees es ois a: <a'saceeeuctreac Sacer ee eels cco 202
BGP Messages bbcnaphQ ea MeaR Ea Eee NS oliogs ane sanaSndeeat dacesalouds cat MM ERED Ete a 204
OPEN: Mess agetettiratestsces.sascsasiCegRet sncensesctc csSsueeso s 205
Contents vii
PED ARE Nessag eien:n Aha te ea tei Ane Oe 208
ENS TAO MV los sa0 6s, ccs each titan re Pennie oe ee 210
BeI N Eel essar one arn ee es ee ene At
Ree Gee RPES L Messager ee ie ree eas 241
HEWNe ye NECA AISELE CGR eet eee east cos cco eee ar sachin Se rT ee eee eR VoL re SETS Prema ZZ
Sele ASE Gog Wao 916)0 |o ne ep ty. MRR La enrich a atri METVA s pate RE Ao Ener 215
POOPY Ca A CSIDMtC acces. Bee arr art ae a rorer 245
Peer POUL SECRID U l Cers csrict on ices cae eee nae ane heb e,
Prebml L OW A teri pte as, ..cszpcaeoma sammaeeriretees tseas osaeveioana es 215
eeem eer ei tirinnte “a art io et renee 216
PPGOy C ra PoA TITIDUTE cot teeter ree entire ere: aay
Ae ee ee) RO PEL TIDULCE, Jostein od scbe ate ee er oe earn Drone cds 21g,
Ey ale ENGEL TIE O TS 282, carat cca Oeeh eee eee eae neta > pales
OREN oor Ati butes cunt ore ee ere eee treet enn 21
[Go (ele bets loa gc ney Aint 9 ¢1 610& A A ERR ee ote rely tnd moa Sir poi 218
AP ae tee Era ek eA tribute 2G. reeee e oes. 218
NPN ee feribete ceecee ttee team v et erersese8 219
SUMAN MALY eas oats peasaarsovead ec abewrnsvebevseasnek dneshénarvavsndetaseeegssicstrstescegncascranes pg Us)
Chapter 7: MPLS—Multi-Protocol Label Switching .........ssssseereeereeees Zan
MPLS Operation .......scssssocscsssssenssecsescsessnecssncenssssssessvessensnssacessasnesssnensenenensenens PID)
UE) es iene Ne ee EO EERE rr NRE ee LO)
Selecting Labels........ccesesssssesescseseseeeeeeeenenesesesssssesrenenenenenesenessesseeeeneeenens 225
Distributing Labels...........cccccccesseseseteneeeeeeeteeeeseseeesnenseeeeeneneneneneneesesenenens 225
NB ae ce ee iF as co vin covscecnatlled svasidnticye Vodeant eeu aetan aera ated 27,
MPLS Message Formats........cscssscecsssescessseseeneceereseesssesseessssencensacenensnserensanenensen 252
CFe TETICU Oerceadbsl pdsiselacvsedanctrosslnetcpapreaereseaato rstsess 233
MPLS and Frame Relay.........cccccsssscsesesesereseeeseeeeeeseseeeeneneneneneneneneseseeeeeenes 235
MPLS and Asynchronous Transfer Mode ....-..:t:ersetee eeees tesee sete rs 236
237
UPS arid VOILE ees co peseccscecsssuccscstonssanecdsansodsnsnsustaseusceodnesncormuaiecetsusnorcanasiies
DATS rd RC eras aces aataeacadcnactaesanecinsensseentea+eonsidanaed¥meezecenatacembanaeeer ?2 42
SU GAMALY occqneeseeee tate cans onennedacenaecnsecoenncasaneanssptigevenmasseer e?s vtsedoen dtorn ee tdotndaae <>2 42
viii _ - IP Switching and Routing Essentials
Chapter 8: LDP—Label Distribution Protocol .........ccsscccesrcssreessresoreeeees 245
LDP Operatici ar ec ors ceca sets ws sists ssvscat sass oyr one Acee nye ena eee een eee ees 245
Meeting Neth bors: .5....c1...00:cssbstenno opeersatees neaorerd eenetsaenge d«eaec esreenace s 246
Exstabliohiing SeSSiOMs suse csasanoscetny neartevymeae ereta eeeeee reeresct a 247
Haxceliaemtnn peL a Dels ys sac-sisicaesendhesea tausec niatrio-n ocsesrntsi eosree nereen t 248
Teale lsR EPSINCOLI LS. cand ca ou wsoueva tobi ene eee ae te 250
TOD CLC CHLO Is occ atscscieua Hae cuctenc aceeeas tara tee ee ae et cena saan ieee ec aa 252
Comstramt- Based Routing so. c..os.usmca since ses speea nes cachcdaeeas- pay ooteeeameras 254
EDP Message: Fo timiats.:s.c.sciceasscs. nascensmseucasdstuonse ysece aoetnsagsteuacse oans teoataannns sen er2 57
Generali DP Messages. coisas: sacesteen eens or oe it to yikes ones 257
NotiiGation Message. ...:..sein ceeet0rat.ah .Re.e ese eeeeeu see 262
PreH GM CSSA9 6 5 veisedueisdinzacsnesasesrancoutons seccumtins-Boavandnocbtoce hyseick teht aay RCeaoce 265
Initialization Message: «...000sep.a ceecss ni.e cSs.c dertres e-ees eeesr 267
Keep Alive Messis.a.. vccndsevacc secon mes errs scons sctsae ts Chess: See eee 269
dress MI 658006 x aciscanss 3ttousesk eee cet ee ARE cs ee eee 270
cddress: VVi thdraw, Message are shen Att aids ten cee ee ae Diy
abelIiam ping IMCSS Age cases ret coon. stort sper tseaartacusenescans eee eee 271
MabelvReaiest: Niessage ..cesmesere: a saoats cacowss eressoies. (a nnrnen ae eee ene 276
abel Withdraw IVieseape rs re ect Pinot dts tel Be ee ee 2/9,
Label Release Viccsi o c asx reer er fcc acento ovina,A vo cee ee ee 200
Wabel Abort: Request Nessag e tccc..tiastes- cnsssan-cccacvsosa-tes ceateikt ecSe s 280
SUITER Y PDs eae v deepen ate oe Ae ress ee 280
Chapter 9: RSVP-TE—Resource Reservation for Traffic Engineering......283
Resource Reservation 2..:.wtemenere: ncrssossouccsteet ace terete ccc ee 284
BV Bee ratio inc... ssa cc0 een see ears estes cetwo o hee Meee eas oes 0 kc 286
EMO WS. sseaos cs ven cals eee Maree eee ot sans sieclhee 286
TRESCLVATIONS . ccesacereneercntn catncs saselccteae eRe ee kl. ne 287
Patin Wessagesy. ances tcavcrnscsns shes cance as tee ceeettatrcne ens: crs coc toga eee 289
Meroing Reservation INequests.....s:ta.tecc sa-sac:sncceu.s5ec mtemt eereeees 27
REGREVAtIOIT S CyL OS arrears fences cctncenmee meee tee ear teeta uous cass ee 292
RSVP dad Dynamo Networks |...) cecseeg net teen ferns vsicaincyeere 294
Optimizirig’? RS VPMe ctormance sc... teeettere eee acc 297
Extensions for Niabie-E ngineée ring ce. .0ccsc:< eee ais: case 298
RSVP Miessagie® FOiinigts sents scc..s..c.<c spe eeeencen veo ese eR ee os 299
