CCIE Routing Protocol Part3MPLS VPNWord格式.docx

CCIE Routing Protocol Part3MPLS VPNWord格式.docx

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MPLSLabelDistribution:

ForCell-mode:

LabelSpace（Per-interface）,LabelGenerate/Distribute/Allocation（DownStream-on-demand/OrderedControlmode）andLabelretention（Conservativelabelretentionmode-onlykeeprequestedlabel）

ForFrame-Mode:

LabelSpace（Per-platform）,LabelGenerate/Distribute/Allocation（UnsolicitedDownStream/Independentcontrolmode）andLabelretention（liberallabelretentionmode-keepallreceivedbutonlyonebeused）

ForCiscoRouter:

Per-platform/UnsolicitedDownStream/independentControl/Liberallabelretention

ForCiscoATM:

per-interface/Downstream-on-demenddistribute/independentcontrol/conservationlabelretention/orderedcontrol

ForRouterwithATMinterface:

likeATM,justuseconservativeorliberallabelretention.

LDP:

usesUDP/TCP646,TDPusesTCP711

LDPHellousingUDPpacketto224.0.0.2（allRouterMulticastaddress）withTTL=1tofindneighbor.thenuseTCPtoestablishthesessionfromHigherIP@tolowerip@andtheninitializationsessionformessageexchangethenexchangemessageafterthis,keepalive,andRouterbuildupLabelmaptable.

LabelTables:

FEC:

FECisusedtodescribethepacketsthatareforwardedbasedonacommoncharateristicsuchasDestinationaddress/subnet,Qosclass...,LabelisassignedtoaFEC.

LSP:

LabelSwitchedPath,ThatisasequenceofLSRsthatforwardlabeledpacketsthroughacertainFEC.itisuni-directional.

FIB/RIB:

DestinationsubnetandNext-hop

LIB:

Learnfromdownstreamneighborabout"

ipprefixwithitslabel"

basedonthismapping,generatealocalsignificantlabelandannouncethislabelandipprefixtoupstreamneighborviaLDP

LFIB:

Itisatableinculdes:

locallabel（whichbeadvertisedtoupstream）mapwithlearnlabel（whichislearnfromdownstream）.iflearnFECfromtwoLSRs,localLSRselectoneofthembasedonFIB.

MPLSloopdetection:

LDPloopdetectionbuildintoIGPloopdetectandTTL.bydefault,oningress,TTLcopyfromIPpacket'

sTTL,ategress,LabelTTLcopiedtoIPheaderTTLfield.ifTTL=0,droppacket.

MPLSconvergence:

whenalinkfailure,IGPconvergenceandthenMPLSconvergence

whenthelinkrecovery,RoutingprotocolrebuildRTandatthistime,labelswitchingshouldbebrokenuntilLFIBandFIBrebuild.

MPLSMTU:

becauseaddlabels,theframesizeisbiggerthannormal,1500Bippacket+3labels（4timesof3is12B）

SotheMTUshouldbe1512BorforethernetswitchsupportsJumboFrame（GiantFrame）.

MPLSTE:

requirement:

1:

everyLSRhavetoseetheentiretopologyoftheNetwork,

2:

Inthistopology,LSRneedsadditionalresourceinformationforlinks,suchasavailableresourceandconstrains

So,onlyextensionOSPFandISISfitfortheserequirements.

Then.LSRusesRSVP-TEandCR-LDPtoestablishtrafficengineeringtunnelsandpropagatelabels,eachELSRmustbeabletocreateanLSPtunnelondemand.

RSVP-TE:

Therearetwomessagetypes:

PATH（Tear/Error）andRESV（Tear/Error）

ERO/RRO:

EROExplicitRoutingObject,Downstreamdirection（likeAS_PATH,thatisLSPhopbyhoplist）toinfoeachLSRtocheckandreserveresource,therearetwoERO,oneisstrictandotherisloose.strictmeansthisHopmustbypassandthisHopandit'

slastHopmustconnectdirectly.

RROisRecordRouteObject,itisupstream

ResourceInformationDataBase,itisaextendnetworktopologywithresource,byCSPF（useLSA9,10tocarryTE-releventlinkattribute）andISIS-TE（newTLVs,TLV22,TLV134,TLV135）

PriorityandPreemption（Setuppriorityandholdingpriority）:

MultipleLSPtunnelswillbeestablished,setupbasedonhigherpriorityfirst,Ifthelinkresourceisnotinsufficient,existingLSPtunnelwithlowerholdingprioritycouldbereleasedresourceforhighersetupprioritytunnelmeanspreemption.

MPLSTEhavetwolabels:

toplabelpointstotheendpointoftrafficengineeringtunnel,thesecondlablepointstodestination.

MPLSVPN（peertopeerVPN）:

TherearetwotypesVPN,

oneisOverlayVPN,SPprovidesVirtualPoint-to-pointlinksbetweenCEs,

suchas（layer-1:

T1/ISDN/SONET;

Layer-2:

FR/ATM/X.25;

layer-3:

GRE,IPSec）

oneisPeer2PeerVPN:

SPparticipatesinCustomerroutingandseparateforwardingtableforeachcustomer.

ControlPlane:

（GlobalRoutingTable/BackBoneIGPTable/VRFtable/VPNv4RoutingTable/RD/RT）

VRFtable:

IPv4prefix,VRFroutingtableisisolatedbetweeneachother,setupVRFatPEconnectingtoCE

VPNv4RoutingTable:

VPNv4prefixarepropagatedacrosstheMPLS-VPNNetworktopeerPEbyMP-iBGP,soVPNv4prefixmustbeuniqueinthewholeMPLSnetwork.

RD（routedistinguisher）:

64bits,MPLSVPNuseaddRDtomakeeachIPv4prefixtobecomeauniqueVNPv4prefix.SoallowCERoutesaddressoverlap.RDisnottheidentifieroftheVPN,SosameVPN,allowtohavedifferentRDs.

forexample:

RDtypeisASN:

nnorIP@:

nn,thefirstoneisprefer.ifaVRFipv4prefixis10.1.1.0/24,RDis65001:

11,soVPNv4prefixis65001:

11:

10.1.1.0/24

RT（Routertargets）:

usingBGPextendedattribute（Community）,itwillbepropagatedbyMP-iBGPupdate.

whentherouteprefixisredistributedfromVRFroutingtableintoMP-iBGP,addexportRT,toidentifythisroutebelongtowhichofVPN.AtthereceiverPE,comparevpnv4prefix'

scommunity（ExportRT/ImportRT）withlocalsettingwhichisImportRT,ifmatch,receivethevpnv4prefixandconverttoVRFipv4prefix,ifnotmatch,rejectit.

SoMPLS-VPNusingRDandRTtocompletetherouteprefixuniquenessandidentifierofVPNandpropagatetheseprefixusingMP-iBGPbetweentwoPEs.

aVPNv4prefixallowtocarrymultipleRTs（ImportRTsandExportRTs）.ImportRTmeanswhichVPNv4prefixwillbeaccepted;

ExportRTmeanstowhomwillthisVPNv4prefixbeallowedtosend.

DataPlane:

TheCoreisBGPfree,SoonlyPEsrunMP-iBGP,OnlyPEsknowtheVPNv4prefix,Pdonotknowthem.Sotherearetwolabels,ToplabelusedtoforwardpackettoPeerPE,andtheBottomlabelusedtoidentifyVPN.

FortheToplabels,AllPEsandPsrunIGPandLDPorRSVP-TE.CoreIGPcreateaglobalroutingtable（ipv4prefix）andgenerateLFIBatallPsandPEs.ThisisToplabeltoensurepacketwillbeswitchingfromingressPEtoegressPE.

TheBottomLabel:

itisvpnlabel,beadvertisedbyMP-iBGP,WhenVPNv4prefixbepropagatedfromonePEtopeerPE,PeerPEdecidewhichVRFtheseprefixbelongto.

AtIngressPE,itaddtwolabels（GlobalIGPlabelasthetoplabel;

VPNlabelasthebottomlabel）

attheegressPE,ItcanmaplabeltoVPNv4prefix,thislabelisVPNlabel,andthisPEadvertisedthelabelalongwiththeVPNv4prefixtoallpossibleingressPEs,ThislabelcontainedintheNLRIfieldofBGP.

MP-iBGP:

allPEsrunMP-iBGP.soiftherearemanyPEs,youshouldsetupRRanduseRTtoletRRknowallVPNv4prefix.thatmeansRRwillreceiveallVPNv4prefix.

OryoucansubdividetheVPNv4prefixintogroupsandsetupseveralRRsorRRgroupstocarryoneofthosesubsets.

WhenaPEredistributeVRFipv4prefixintoMP-iBGP:

1:

AddRD

2:

Modifythenext-hoptoRE'

sRID

3:

AddVPNlabelbasedonVPNv4prefix

4:

AddRTs

MPLS-VPNPE-CERouting:

StaticRouting/connectedbetweenPEandCE

redistributeConnectedroutesintoBGP,LetremotePEknowtheseconnectedIP@,whenpingfromCEtoCE,pingsuccessfully.Soifpingwithaspecifiedip@assource,youmustmakesureRemotedevice（PEorCE）knowittoguaranteereplypacketsuccessfully.

Routerbgp65001

........

address-familyipv4vrfCus_A

redistributeconnected

neighbor10.10.10.2remoteas65001

neighbor10.10.10.2active

Forstatic:

iproutevrfCus_A10.100.0.0255.255.0.010.10.10.25

routerbgp65001

redistributestatic

RIPv2BetweenPEandCE

ipvrfCus_A

rd1:

1

route-tragetexport1:

import1:

routerrip

noauto-summary

version2

network10.0.0.0

redistributebgp65001

default-metric2

redistributerip

OSPFbetweenPEandCE

Q1:

usually,theMPLS-VPNasaSuper-BackBonearea,soCEsendOSPFLSA3toPE,whichisaintra-summaryrouteatPE,thenPEredistributetheseroutesintoBGP,thenremotePEredistributeBGPintoOSPFagain.atRemotePE,theseformerLSA3hadbeenchangedtoLSA5becausered