CRNET與城域網(wǎng)建設(shè)

技術(shù)交流思科北京公司喻超CCIE#5329CRNET網(wǎng)絡(luò)概況及建網(wǎng)思路和原則MPLSVPN的業(yè)務(wù)及關(guān)鍵技術(shù)L2二層VPN的應(yīng)用匯報(bào)提綱廣東省在CRNET骨干網(wǎng)網(wǎng)絡(luò)的位置CRNET建網(wǎng)思路和城域網(wǎng)建設(shè)指導(dǎo)原則CRNET堅(jiān)持全程全網(wǎng)，統(tǒng)一管理初期不建設(shè)獨(dú)立的省網(wǎng)，城域網(wǎng)和CRNET直接相連各城域網(wǎng)為CRNET密不可分的組成部分，城域網(wǎng)是骨干網(wǎng)業(yè)務(wù)在城域的無(wú)縫延伸在CRNET的基礎(chǔ)上，提供全國(guó)范圍的MPLSVPN服務(wù)將CRNET擴(kuò)展成可提供綜合多業(yè)務(wù)的數(shù)據(jù)平臺(tái)CRNET部分權(quán)力將下放到分公司，總部保留相對(duì)全力和監(jiān)管能力區(qū)域網(wǎng)絡(luò)連接拓?fù)鋱D(華南)B類節(jié)點(diǎn)A類節(jié)點(diǎn)C類節(jié)點(diǎn)長(zhǎng)沙懷化株州郴州常德衡陽(yáng)婁底岳陽(yáng)柳州深圳東莞肇慶茂名中山汕頭佛山順德華南區(qū)（廣州）湛江桂林南寧155M622MCH3CH4昆明CH3CH3CH4CH4CH4CH4CH4CH4CH4CH4CH4武漢廣州廣州鐵通網(wǎng)絡(luò)與CRNET骨干網(wǎng)A1類（上海、廣州）節(jié)點(diǎn)結(jié)構(gòu)圖ATM/FRDNS/NTP/CACHENETFOLW寬帶接入撥號(hào)接入VLAN2-VLANnHSRP其它A類B類A1-CR1A1-CR2dGRAR2-1SW2MPLSPE帶外管理電源控制口以太I(xiàn)PPhoneChinaNet/GBNUUNET/AT&T/...POS155RR-1RR-2其它A類AR1VPN用戶接入AR2-2GECH3GEiGRGECH4CH4GEGEGEGECH4CH4CH4CH4CH4GECH1GSR12416GSR1240610GDWDM1Gethernet622MSTM-4100BaseT155MSTM-1圖例：CH3FECH4CH1GECisco7200高速接入/...B類節(jié)點(diǎn)結(jié)構(gòu)圖（深圳）帶外管理電源控制口以太深圳CR-B撥號(hào)接入

專線接入（64K-8M）FR接入IPPhone城域網(wǎng)業(yè)務(wù)類型：

以太接入/寬帶接入DNSFR/DDN/專線接入/...Cache/Netflow城域網(wǎng)/寬帶接入MPLSPEVPN用戶接入深圳AR1AR4SW1SW3DLCIsubinterfaceIPPhone北京1Gethernet622MSTM-4100BaseT2M/V.35圖例：B-CRGSR12406AR1GSR12406AR4SW1說(shuō)明：1.圖中實(shí)線框內(nèi)設(shè)備為既有。2.圖中虛框內(nèi)設(shè)備不在本工程內(nèi)提供。3.至C類節(jié)點(diǎn)通道采用STM-1或捆綁2M。Cisco7200Siwtch撥號(hào)接入NASAS5300B類節(jié)點(diǎn)拓?fù)浣Y(jié)構(gòu)圖CH3GE155MSTM-1FECH4CH3GECH4FEGEFEFEFE說(shuō)明：圖中虛框內(nèi)設(shè)備不在本工程內(nèi)提供。圖例：AR5SW4Cisco7200Switch155MSTM-1/N×2M10/100BaseT2M/V.35/V.24用戶網(wǎng)絡(luò)VLAN2-VLANnAR5SW4DSU/CSUDSU/CSUVLAN1NAS撥號(hào)接入廣州CR帶外管理電源控制口以太1GethernetC類節(jié)點(diǎn)網(wǎng)絡(luò)拓?fù)鋱DCH4GEFEGEFEFECH4AR5CH4其他C類節(jié)點(diǎn)結(jié)構(gòu)圖城域網(wǎng)建設(shè)的服務(wù)模式－綜合多業(yè)務(wù)服務(wù)話音業(yè)務(wù)200-300元/電話（企業(yè)）100元/電話（個(gè)人）internet接入100元/家庭1000元/企業(yè)VPN業(yè)務(wù)1000-2000元/節(jié)點(diǎn)Video業(yè)務(wù)60元/小時(shí)/節(jié)點(diǎn)內(nèi)容提供業(yè)務(wù)視內(nèi)容來(lái)確定提高在單一數(shù)據(jù)線路上的業(yè)務(wù)收入來(lái)源/ARPU電話傳真單一數(shù)據(jù)線接入視頻會(huì)議終端IP電話個(gè)人用戶/網(wǎng)上游戲服務(wù)一線通多業(yè)務(wù)服務(wù)平臺(tái)VPN業(yè)務(wù)/互聯(lián)網(wǎng)業(yè)務(wù)數(shù)據(jù)存儲(chǔ)/信息共享綜合多業(yè)務(wù)服務(wù)是電信網(wǎng)絡(luò)的必然之路杭州CNC案例杭州CNC網(wǎng)絡(luò)狀況開(kāi)展的業(yè)務(wù)務(wù)企業(yè)虛擬專專用內(nèi)部網(wǎng)網(wǎng)/虛擬專專用外部網(wǎng)網(wǎng)因特網(wǎng)訪問(wèn)問(wèn)主機(jī)托管/虛擬主機(jī)機(jī)VOD/遠(yuǎn)程教育/交互式電電視/遠(yuǎn)程程醫(yī)療呼叫中心IP電話/可視視IP電話電子抄表家庭保安遠(yuǎn)程監(jiān)控網(wǎng)上游戲/網(wǎng)上炒股股信息點(diǎn)播（（氣象/交交通/旅游游/新聞））用戶情況有線電視用用戶150萬(wàn)。市區(qū)區(qū)46萬(wàn)目前上網(wǎng)人人數(shù)：6萬(wàn)萬(wàn)多戶3000多多企業(yè)虛擬擬網(wǎng)接入節(jié)節(jié)點(diǎn)內(nèi)容服務(wù)，，IDC數(shù)據(jù)中心服服務(wù)IP電話超市盈盈利10萬(wàn)/天綁定銷售/銷售電腦腦贈(zèng)寬帶目前1000萬(wàn)/月月的盈利CNCConnect案例城域網(wǎng)建設(shè)設(shè)的服務(wù)模模式－多業(yè)業(yè)務(wù)服務(wù)城域網(wǎng)建設(shè)設(shè)的服務(wù)模模式－多業(yè)業(yè)務(wù)服務(wù)全業(yè)務(wù)提供供－鐵通城城域網(wǎng)服務(wù)質(zhì)量保證應(yīng)用托管內(nèi)容托管無(wú)線互聯(lián)網(wǎng)主機(jī)托管視頻會(huì)議軟交換…從接入層到到骨干網(wǎng)業(yè)務(wù)匯聚點(diǎn)點(diǎn)IP語(yǔ)音數(shù)據(jù)專線互聯(lián)網(wǎng)接入入內(nèi)容推送鐵通城域網(wǎng)網(wǎng)DSL無(wú)線幀中繼ATM專線以太網(wǎng)接入層長(zhǎng)途多業(yè)務(wù)務(wù)平臺(tái)長(zhǎng)途波分ATMCRNET核心數(shù)據(jù)網(wǎng)網(wǎng)集成的模型型專注于業(yè)務(wù)務(wù)開(kāi)展城域DWDM城域DPTSDH多業(yè)業(yè)務(wù)平臺(tái)以太網(wǎng)MSTP全國(guó)范圍的的MPLSVPN服務(wù)業(yè)務(wù)目標(biāo)市場(chǎng)－－高端企業(yè)業(yè)用戶（ARPU值）MPLSVPN作為接入的的手段基于MPLSVPN的增值服務(wù)務(wù)是源源不不斷的利潤(rùn)潤(rùn)來(lái)源具有鐵通優(yōu)優(yōu)勢(shì)和特點(diǎn)點(diǎn)的全國(guó)MPLSVPN服務(wù)是制勝勝的關(guān)鍵有針對(duì)性的的擴(kuò)大覆蓋蓋面，逐步步實(shí)施基于CRNET全國(guó)范圍的的MPLSVPN業(yè)務(wù)CRNET寬帶數(shù)據(jù)網(wǎng)網(wǎng)鐵道部北北京VPN北京總部鐵道部上上海VPN上海分部吉林分部武漢分部廣州分部鐵道部成成都VPNMPLSVPN業(yè)務(wù)及相關(guān)關(guān)技術(shù)多業(yè)務(wù)服務(wù)務(wù)的具體實(shí)實(shí)現(xiàn)MPLSVPN的安全性互聯(lián)網(wǎng)大樓A小區(qū)BInternet高速接入業(yè)業(yè)務(wù)鐵通IP寬帶城域網(wǎng)絡(luò)企業(yè)C學(xué)校D互聯(lián)網(wǎng)FE/GELRE/ADSLWirelessHFC端口帶寬用戶端設(shè)備備用戶端設(shè)備備A用戶1A用戶2使用原有私私有地址寬帶互連－－10/100M以太網(wǎng)，低低成本，高高帶寬MPLSVPN企業(yè)內(nèi)聯(lián)網(wǎng)網(wǎng)－用戶內(nèi)內(nèi)部網(wǎng)絡(luò)互互連增加虛擬專專用網(wǎng)A的路由IP寬帶城域網(wǎng)絡(luò)平同時(shí)可輕松松提供針對(duì)對(duì)不同業(yè)務(wù)務(wù)的多VPN服務(wù)如語(yǔ)音，視視頻，財(cái)務(wù)務(wù)，人事等等互聯(lián)網(wǎng)A用戶1A用戶2虛擬專用網(wǎng)網(wǎng)A路由增加互聯(lián)網(wǎng)網(wǎng)訪問(wèn)路由由互聯(lián)網(wǎng)訪問(wèn)問(wèn)IP寬帶城域網(wǎng)絡(luò)用戶端設(shè)備備用戶端設(shè)備備在提供企業(yè)業(yè)內(nèi)聯(lián)網(wǎng)業(yè)業(yè)務(wù)基礎(chǔ)上上，利用同同一線路，，統(tǒng)一的IP寬帶網(wǎng)絡(luò)平平臺(tái)提供互互聯(lián)網(wǎng)訪問(wèn)問(wèn)業(yè)務(wù)。同時(shí)可輕松松提供針對(duì)對(duì)不同業(yè)務(wù)務(wù)的VPN服務(wù)如語(yǔ)音，視視頻，財(cái)務(wù)務(wù)，人事等等MPLSVPN企業(yè)內(nèi)聯(lián)網(wǎng)網(wǎng)－用戶內(nèi)內(nèi)部網(wǎng)絡(luò)互互連同一線路訪訪問(wèn)互聯(lián)網(wǎng)網(wǎng)ClassicalInternetAccessAddressingTheCustomercanuseprivateaddressspace.ThefirewallprovidesNetworkAddressTranslation(NAT)betweentheprivateaddressspaceandthesmallportionofpublicaddressspaceassignedtothecustomer.PrivateaddressesPublicaddressesInternetAccessfromEverySite——AddressingTwoaddressingoptions:EveryCErouterperformsNATfunctionality—asmallpartofthepublicaddressspacehastobeassignedtoeachCErouter.ThecustomerusesonlypublicIPaddressesintheprivatenetwork——notrealisticformanycustomers.PrivateaddressesPublicaddressesCentralFirewallServiceTrafficFlowInternetInternetAccessVPNVPNCustomerACE-A1CE-A2VPNCustomerBCE-B1CE-B2CentralFirewallTrafficbetweensitesofonecustomershouldflowinsidetheVPN.Trafficbetweencustomersisnotallowed;asecuritybreachcouldoccur.TrafficcanflowfromcustomersitestotheInternetandback;customersitesareprotectedbyacentralfirewall.CombiningInternetAccesswithVPNServicesTwomajordesignmodels:InternetaccessofferedthroughyetanotherVPNInternetaccessofferedthroughglobalroutingonthePEroutersInternetAccessinaVPNBenefits:TheproviderbackboneisisolatedfromtheInternet;increasedsecurityisrealized.Drawbacks:AllInternetroutesarecarriedasVPNroutes;fullInternetroutingcannotbeimplementedbecauseofscalabilityproblems.InternetAccessThroughGlobalRoutingTwoimplementationoptions:InternetaccessisimplementedviaseparateinterfacesthatarenotplacedinanyVPNrouting/forwardinginstance(VRF)(traditionalInternetaccesssetup).PacketleakingbetweenaVRFandtheglobaltableisachievedthroughspecialconfigurationcommands.InternetAccessThroughPacketLeakingBenefits:ThismethodcanbeimplementedoveranyWANorLANmedia.Drawbacks:InternetandVPNtrafficismixedoverthesamelink;securityissuesarise.MorecomplexInternetconnectivityoptions(forexample,fullInternetroutingforcustomers)arehardtoimplement.PacketLeakinginActionPEPEInternetSite-1PE-IGSite-2Network/16Serial0VPN-AVRF/0(global)Site-1routes

Site-2routesGlobalTableandFIB/32Label=3/32Label=5...IPpacketD=Label=3IPpacket

D=IPpacketD=InternetAccessThroughaDedicatedSubinterface—TrafficFlowPEPESite-1PE-IGSite-2Network/16Serial0.1Serial0.2Serial0.1Serial0.2CEroutingtableSite-2routes---->Serial0.1Internetroutes--->Serial0.2IPpacketD=PEGlobalTableInternetroutes--->,Label=3InternetLabel=3IPpacket

D=IPpacketD=互聯(lián)網(wǎng)A用戶1A用戶2虛擬專用網(wǎng)路路由互聯(lián)網(wǎng)訪問(wèn)路路由增加虛擬專用用網(wǎng)B的部分路由互聯(lián)網(wǎng)訪問(wèn)B用戶1增加虛擬專用用網(wǎng)A的部分路由用戶端設(shè)備用戶端設(shè)備用戶端設(shè)備在提供企業(yè)內(nèi)內(nèi)聯(lián)網(wǎng)，互聯(lián)聯(lián)網(wǎng)訪問(wèn)業(yè)務(wù)務(wù)基礎(chǔ)上，利利用同一線路路，統(tǒng)一的IP寬帶網(wǎng)絡(luò)平臺(tái)臺(tái)提供企業(yè)外外聯(lián)網(wǎng)業(yè)務(wù)。。IP寬帶網(wǎng)絡(luò)平臺(tái)臺(tái)MPLSVPN企業(yè)外聯(lián)網(wǎng)－－外部網(wǎng)互連連運(yùn)營(yíng)商之運(yùn)營(yíng)營(yíng)商業(yè)務(wù)運(yùn)營(yíng)商之運(yùn)營(yíng)營(yíng)商Customer-ISP不運(yùn)行MPLSCRNETPE-1PE-2CE-1CE-2中經(jīng)網(wǎng)沈陽(yáng)陽(yáng)IGP中經(jīng)網(wǎng)北京京IGPISPcustomersASBR-1ASBR-2ISPcustomersNetwork=NIP

Dest=NIP

Dest=N1

IP

Dest=NIP

Dest=NIP

Dest=NIP

Dest=N2

IP

Dest=NIP

Dest=N1

6

CarrierBackbonePE-1PE-2CE-1CE-2ISPcustomersASBR-1ASBR-2ISPcustomersNetwork=NIP

Dest=NIP

Dest=NIP

Dest=NIP

Dest=N3IP

Dest=N2

IP

Dest=N1

6

IP

Dest=N1

IP

Dest=N15

IP

Dest=N7

運(yùn)營(yíng)商之運(yùn)營(yíng)營(yíng)商Customer-ISP運(yùn)行MPLS中竟網(wǎng)沈陽(yáng)陽(yáng)IGP中經(jīng)網(wǎng)北京京IGP運(yùn)營(yíng)商之運(yùn)營(yíng)營(yíng)商Customer-ISP運(yùn)行MPLS-VPNCarrierBackbonePE-1PE-2CE-1CE-2I-PE1I-PE2Network=NIP

Dest=NIP

Dest=NIP

Dest=N12

3

IP

Dest=N12

2

IP

Dest=N1

6

12

IP

Dest=N1

12

IP

Dest=N25

12

IP

Dest=N7

12

IP

Dest=N12

中竟網(wǎng)沈陽(yáng)陽(yáng)IGP中經(jīng)網(wǎng)北京京IGP網(wǎng)際MPLSVPN業(yè)務(wù)CATV/CNCCRNET網(wǎng)際MPLSVPNPE-1PE-ASBR1CE-1CE-2P1Network=NPE-ASBR2PE-2P2IP

Dest=NIP

Dest=N20

8

IP

Dest=N20

IP

Dest=N12

IP

Dest=N1

6

IP

Dest=N1

IP

Dest=NA用戶1A用戶2虛擬專用網(wǎng)網(wǎng)A路由互聯(lián)網(wǎng)訪問(wèn)問(wèn)路由虛擬專用網(wǎng)網(wǎng)B的部分路由由增加話音VPN的部分路由由B用戶1IP電話通道道V網(wǎng)關(guān)PSTN/GSM國(guó)家級(jí)長(zhǎng)途途VOIP智能軟交換換關(guān)守IP電話傳統(tǒng)電話（鐵通號(hào)碼））（鐵通號(hào)碼））互聯(lián)網(wǎng)互聯(lián)網(wǎng)訪問(wèn)問(wèn)電視會(huì)議用戶端設(shè)備備在提供企業(yè)內(nèi)聯(lián)網(wǎng)，互聯(lián)網(wǎng)訪問(wèn)業(yè)務(wù)，企業(yè)外聯(lián)網(wǎng)業(yè)務(wù)基礎(chǔ)上，利用同一線路，統(tǒng)一的IP寬帶網(wǎng)絡(luò)平臺(tái)提供企業(yè)IP電話業(yè)務(wù)。IP寬帶網(wǎng)絡(luò)平平臺(tái)MPLSVPN－－－語(yǔ)音/電視視會(huì)議專用用VPN電視會(huì)議與廣電基于于VoiceOverCable的合作HFCGatekeeperPSTNVCATVIPMANIP電話VPN鐵通城域IP網(wǎng)絡(luò)IP電話VPN智能軟交換換智能軟交換換CMTSCableModem成本投入:SoftSwitch每線的成本本10-20$所有的用戶戶接入的電電話CableModem由CATV投資收入:15-20￥/每月月/用戶市市話收費(fèi)一年內(nèi)即可可通過(guò)市話話費(fèi)收回投投資，以后后的收入即即純利潤(rùn)用戶的長(zhǎng)途途話務(wù)可通通過(guò)鐵通的的PSTN長(zhǎng)途骨干或或VoIP骨干，假設(shè)設(shè)30￥/每月/用用戶，2000用戶戶可每年給給鐵通帶來(lái)來(lái)額外的2000*30*12=72萬(wàn)￥￥賣(mài)點(diǎn):CATV在提供數(shù)據(jù)據(jù)的同時(shí)，，為用戶提提供話音，，幫鐵通放放號(hào)鐵通在最小小的成本情情況下，擴(kuò)擴(kuò)大鐵通的的用戶覆蓋蓋范圍用戶在享受受數(shù)據(jù)，語(yǔ)語(yǔ)音，是鐵通，廣廣電，用戶戶三贏的局局面城域MPLSVPN網(wǎng)吧聯(lián)盟網(wǎng)吧聯(lián)盟2接入上網(wǎng)網(wǎng)吧聯(lián)盟1接入上網(wǎng)＋話音網(wǎng)吧聯(lián)盟1接入上網(wǎng)網(wǎng)吧聯(lián)盟2接入上網(wǎng)＋話音CRNET骨干PEPEPP鐵通城域網(wǎng)網(wǎng)PEV話音VPN普通接入點(diǎn)話音Site1Site2Site3Site4Site5Site6普通上網(wǎng)Site7，8網(wǎng)吧間共享享資源/聯(lián)聯(lián)網(wǎng)游戲/VoIP通話/可視視聊天鐵通城域網(wǎng)企業(yè)具體業(yè)業(yè)務(wù)分析城域?qū)拵P網(wǎng)絡(luò)平臺(tái)以太網(wǎng)交換換機(jī)互聯(lián)網(wǎng)某企業(yè)分部部/某大樓樓MPLSVPN連接本部和和分部電視會(huì)議企業(yè)AIP電話企業(yè)A分部電視會(huì)議IP電話企業(yè)A總部MPLSVPN連接本部和和分部IDC數(shù)據(jù)中心主機(jī)托管二級(jí)運(yùn)營(yíng)商商/內(nèi)容提提供商網(wǎng)上教學(xué)/學(xué)習(xí)內(nèi)部信息共共享視頻點(diǎn)播互聯(lián)網(wǎng)用戶端設(shè)備備銀行證券公司金融用戶透明傳送業(yè)業(yè)務(wù)－高帶帶寬，高安安全性連接用戶的的以太接口口為二層接接口，無(wú)IP地址Ethernet,ATM,FrameRelayetc同一網(wǎng)段同一局域網(wǎng)網(wǎng)銀行證券公司金融用戶用戶端設(shè)備備IP寬帶網(wǎng)絡(luò)平平臺(tái)L2VPN服務(wù)L2VPN安全、透明明網(wǎng)絡(luò)通道道傳輸業(yè)務(wù)務(wù)A用戶1A用戶2L2VPN業(yè)務(wù)及技術(shù)術(shù)AToML2TPIPVPN技術(shù)CompleteL2andL3VPNSolutionsforbothIPandMPLSL2L3MPLSAToM(draft-martini)RFC2547VPN（MPLSVPN)IPUTI/L2TPv3TBD

RFC2547?AnyTransportoverMPLS(AToM)Providesabilitytotransportlayer2trafficacrossMPLSpacket-basedcorenetworks,extendingtherichnessofMPLScapabilitiestoL2VPNsAscalablearchitecturethatsupportsthemultiplexingofsubscriberconnectionsAstandardsbased(draft-martini)openarchitectureallowsextensibilitytomanytransporttypesDesignedforAny-to-AnyconnectivitySPdoesnotparticipateincustomerroutingMPLSCoreAToMFrameRelayATMLeasedLineEthernetFrameRelayATMLeasedLineEthernetAllowsSPstocombinewithCiscoIOSQoSandMPLSTrafficEngineeringtoprovide““Virtualleasedline”likeservicesAToM––數(shù)據(jù)流程PE1MPLSBackbonePE2AnyTransportoverMPLS(AToM)TunnelMPLSLSPFrameRelayCPERouter,FRADDLCI101CPERouter,FRADFrameRelayDLCI201DirectedLDPLabelExchangeforVC1–Label10LabelExchangeforVC2–Label21VC1––ConnectsDLCI101toDLCI201VC2––ConnectsDLCI102toDLCI202DLCI202DLCI102NeighborLDP––Label50NeighborLDP––Label901011050101109010221501022190IETF標(biāo)準(zhǔn)化IETFworkinggroupPWE3‘PseudoWireEmulationEdgetoEdge’;Requirementsdetailedindraft-ietf-pwe3-requirementsDevelopstandardsfortheencapsulation&serviceemulationof“pseudowires””AcrossapacketswitchedbackboneFocusedonPoint-to-PointcircuitemulationPSNtunnel->GRE,MPLS,L2TPService->Ethernet,ATM,PPP,FR,HDLCandsoon..L2TP協(xié)議參考模模型L2TPv2L2TPv3IPorMPLSCoreL2TPv3TunnelsCECEPE1PE2CECEProviderEdgeSPIPCoreProviderEdgeIPorMPLSCoreL2TPv2TunnelsLNSISP1LACDialUserDSLUserLNSISP2EthernetEthernetFrameRelayFrameRelaySPIPCoreL2TPv3forcustomersthatpreferanativeIPnetworkProvidesabilitytotransportlayer2trafficacrossIPpacket-basedcorenetworksBasedonawell-establishedlineageofprotocols:L2TPv2andpre-standardsCiscoinnovation–UniversalTransportInterface(UTI)AstandardsbasedopenarchitectureallowsextensibilitytomanytransporttypesIPCoreL2TPv3FrameRelayATMLeasedLineEthernetFrameRelayATMLeasedLineEthernetLayer2TunnelingProtocol-version3EfficientheaderforhighperformancedecapsulationConfigurationonEdgeroutersonlyL2TPv3包的封裝?Deliveryheader-ThedeliveryheaderistheheaderneededtocarrytheL2TPv3packetacrossthedeliverynetwork.ThisisanIPv4header.Thedeliveryheaderis20bytes.?L2TPv3header-TheL2TPv3payloadindependentheadercontainsthenecessaryandsufficientinformationneededtouniquelyidentifythetunnelcontextatthede-encapsulationpoint.Thepayloadindependentheaderis12bytes.?Payload-PayloadtobetransportedbyL2TPv3.Itmaybealinklayerframeoranetworklayerpacket.DeliveryHeader20BytesL2TPv3Header12BytesPayloadTunnelIdentifier4BytesTunnelCookie8BytesIPorMPLSCoreIPCoreL2TPv3–數(shù)據(jù)包的流程程Description:TwoEthernetSegmentsarejoinedoveranIPcoreviaL2TPv3.Toenduserdevices,thetwophysicalEthernetnetworksappearasasinglesegment.R2R1L2TPv3TunnelEthernetEthernetIPL2TPEthernetServerBWorkstationAStep#2R1takesEthern