BGP和OSPF在路由重分发时的注意点

RGNOSv10.3(3)

BGP和OSPF在路由重分发时的注意点2008-5-15福建星网锐捷网络版权所有侵权必究前言本文档介绍了RGNOSV10.3(3)中BGP和OSPF路由重发布时的一些实现特点。由于这些特点区别于友商CISCO的BGP功能实现，在具体的工程实施过程中需要注意。本文档仅限公司内部使用，严禁外传。如果您在阅读中产生疑问，请与文档维护人联系。目录1OSPF重分发BGP路由1.1注意点这里Cisco验证的版本为工程RuijieCisco备注BGP路由的下发BGP不会将直连路由下发到核心路由表，因此重分发BGP路由的时候是没有BGP的直连路由BGP会将BGP的直连路由下发到核心路由表，因此重分发BGP路由的时候，会重分发BGP的直连路由解决方法：在OSPF配置BGP的直连路由，参看“重分发BGP的直连路由〞。重分发IBGP路由默认重分发所有BGP路由默认不允许重分发BGP的IBGP路由。在BGP配置模式下可以使用bgpredistribute-internal命令允许IGP协议重分发IBGP路由解决方法：1、RGNOSv10.3(4)将增加支持bgpredistribute-internal功能；2、使用route-map的matchroute-type功能，参看“重分发IBGP路由〞。BGP路由下发的控制不对下发的路由进行控制可以使用table-map修改下发到核心路由表的路由属性解决方法：1、RGNOSv10.3(4)将增加支持table-map功能。1.2应用实例网络拓扑四台设备之间建立EBGP/IBGP/EBGP连接。C1为CISCO3550、C2、C3是Cisco模拟器，R1是我司设备，实验设备为RG-S5750。C1和R1建立EBGP连接，R1和C2建立IBGP连接，C2和C3建立EBGP连接。其中C1和C3主要是发送路由，具体的操作在R1和C2。配置文件C1 简化配置C1#shorunning-configBuildingconfiguration...Currentconfiguration:2557bytes!version12.2noservicepadservicetimestampsdebuguptimeservicetimestampsloguptimenoservicepassword-encryption!hostnameC1!!noaaanew-modelipsubnet-zeroiprouting!!!!!!nofileverifyautospanning-treemodepvstspanning-treeextendsystem-id!vlaninternalallocationpolicyascending!!interfaceLoopback0ipaddress!interfaceFastEthernet0/1noswitchport!interfaceFastEthernet0/2switchportmodedynamicdesirable!interfaceFastEthernet0/3switchportmodedynamicdesirable!...!routerbgp1nosynchronizationbgplog-neighbor-changesredistributestaticneighbor192.168.16.2remote-as23noauto-summary!ipclasslessiproute192.168.111.0255.255.255.0Loopback0iproute192.168.112.0255.255.255.0Loopback0ipserveripsecure-server!!!control-plane!!linecon0linevty04privilegelevel15passwordwlogin!!endC1#C2简化配置C2#shorunnBuildingconfiguration...Currentconfiguration:1450bytes!version12.4servicetimestampsdebugdatetimemsecservicetimestampslogdatetimemsecnoservicepassword-encryption!hostnameC2!boot-start-markerwarm-rebootboot-end-marker!!noaaanew-model!resourcepolicy!ipcef!!!!interfaceLoopback0ipaddress192.168.125.1255.255.255.0secondaryipaddress192.168.126.1255.255.255.0secondaryipaddress!interfaceFastEthernet0/0duplexfull!interfaceEthernet1/0noipaddressshutdownduplexhalf!interfaceEthernet1/1noipaddressshutdownduplexhalf!interfaceEthernet1/2noipaddressshutdownduplexhalf!interfaceEthernet1/3duplexfull!routerospf1log-adjacency-changesnetwork.20.0.0.0area0network192.168.26.0.7area0!routerbgp23nosynchronizationbgplog-neighbor-changesneighbor.6remote-as23neighbor.6update-sourceLoopback0neighbor.6next-hop-selfneighbor192.168.23.2remote-as3noauto-summary!noipservernoipsecure-server!!...!linecon0stopbits1lineaux0linevty04privilegelevel15passwordwlogin!!endC2#C3简化配置C3#shorunnBuildingconfiguration...Currentconfiguration:1178bytes!version12.4servicetimestampsdebugdatetimemsecservicetimestampslogdatetimemsecnoservicepassword-encryption!hostnameC3!boot-start-markerboot-end-marker!!noaaanew-model!resourcepolicy!ipcef!!!!!!interfaceLoopback0ipaddress!interfaceFastEthernet0/0noipaddressshutdownduplexfull!interfaceEthernet1/0noipaddressshutdownduplexhalf!interfaceEthernet1/1noipaddressshutdownduplexhalf!interfaceEthernet1/2noipaddressshutdownduplexhalf!interfaceEthernet1/3duplexfull!routerbgp3nosynchronizationbgplog-neighbor-changesredistributestaticneighbor192.168.23.1remote-as23noauto-summary!iproute192.168.131.0255.255.255.0Loopback0iproute192.168.132.0255.255.255.0Loopback0noipservernoipsecure-server!!!loggingalarminformational!...!linecon0stopbits1lineaux0linevty04privilegelevel15passwordwlogin!!endC2#R1简化配置R1#showrunnBuildingconfiguration...Currentconfiguration:2080bytes!versionRGNOS(3),Release(38105)(FriApr2515:29:44CST2023-ngcf31)hostnameR1co-operateenable!!!!route-mapospf_redistpermit10matchroute-typeexternal!vlan1!!!!!interfaceGigabitEthernet0/1noswitchportnoipproxy-arp!interfaceGigabitEthernet0/2!...!interfaceGigabitEthernet0/23!interfaceGigabitEthernet0/24noswitchportnoipproxy-arp!interfaceLoopback0ipaddressipaddress192.168.165.1255.255.255.0secondaryipaddress192.168.166.1255.255.255.0secondary!!!!!!!!routerbgp23neighbor.2remote-as23neighbor.2update-sourceLoopback0neighbor192.168.16.1remote-as1!address-familyipv4neighbor.2activateneighbor.2next-hop-selfneighbor192.168.16.1activateexit-address-family!!routerospf1router-id.6network.60.0.0.0area0network192.168.26.0.7area0!!!iproute192.168.161.0255.255.255.0Loopback0iproute192.168.162.0255.255.255.0Loopback0!!linecon0linevty010privilegelevel15loginpasswordw!!end检验配置效果C2使用showipbgp可以看到125.0/126.0是源发路由，111.0/112.0/165.0/166.0是IBGP路由，131.0/132.0是EBGP路由。使用showipospfdatabase可以看到，OSPF中没有外部路由。C2#showipbgpBGPtableversionis25,localrouterIDis.2Statuscodes:ssuppressed,ddamped,hhistory,*valid,>best,i-internal,rRIB-failure,SStaleOrigincodes:i-IGP,e-EGP,?-incompleteNetworkNextHopMetricLocPrfWeightPath*>i192.168.111.0.6010001?*>i192.168.112.0.6010001?*>192.168.125.0.0032768i*>192.168.126.0.0032768i*>192.168.131.0192.168.23.2003?*>192.168.132.0192.168.23.2003?*>i192.168.165.0.601000i*>i192.168.166.0.601000iC2#showipospfdataOSPFRouterwithID(.2)(ProcessID1)RouterLinkStates(Area0)LinkIDADVRouterAgeSeq#ChecksumLinkcount.2.2910x800000090x00B6402.6.64980x800000040x00CD202NetLinkStates(Area0)LinkIDADVRouterAgeSeq#Checksum192.168.26.2.2910x800000030x00C1CFC2#R1使用showipbgp可以看到165.0/166.0是源发路由，125.0/126.0/131.0/132.0是IBGP路由，111.0/112.0是EBGP路由。使用showipospfdatabase可以看到，OSPF中没有外部路由。R1#showipbgpStatuscodes:ssuppressed,ddamped,hhistory,*valid,>best,i-internal,SStaleOrigincodes:i-IGP,e-EGP,?-incompleteNetworkNextHopMetricLocPrfPath*>192.168.111.0192.168.16.101?*>192.168.112.0192.168.16.101?*>i192.168.125.0.20100i*>i192.168.126.0.20100i*>i192.168.131.0.201003?*>i192.168.132.0.201003?*>192.168.165.0.00i*>192.168.166.0.00iTotalnumberofprefixes8R1#showipospfdataOSPFRouterwithID(.6)(ProcessID1)RouterLinkStates(Are.0)LinkIDADVRouterAgeSeq#CkSumLinkcount.2.22540x800000090xb6402.6.66590x800000040xcd202NetworkLinkStates(Are.0)LinkIDADVRouterAgeSeq#CkSum192.168.26.2.22530x800000030xc1cf重分发BGP的直连路由C2配置OSPF重分发BGP路由：routerospf1redistributebgp23subnets使用showipospfdatabase可以看到EBGP路由(131.0/132.0)和直连路由(125.0/126.0)都重分发给OSPF，而IBGP路由没有重分发给OSPF。因此可以看出Cisco会向下通告BGP的直连路由〔这里是通过network命令配置的路由〕。C2#shoipospfdatabaseOSPFRouterwithID(.2)(ProcessID1)RouterLinkStates(Area0)LinkIDADVRouterAgeSeq#ChecksumLinkcount.2.2140x8000000A0x00BA392.6.69310x800000040x00CD202NetLinkStates(Area0)LinkIDADVRouterAgeSeq#Checksum192.168.26.2.25240x800000030x00C1CFType-5ASExternalLinkStatesLinkIDADVRouterAgeSeq#ChecksumTag192.168.125.0.2130x800000010x00D6ED0192.168.126.0.2130x800000010x00CBF70192.168.131.0.2130x800000010x00CAF03192.168.132.0.2130x800000010x00BFFA3R1配置OSPF重分发BGP路由：routerospf1redistributebgpsubnets使用showipospfdatabase可以看到IBGP路由(125.0/126.0/131.0/132.0)和EBGP路由(111.0/112.0)都重分发给OSPF的，而这里没有直连路由(165.0/166.0)。因为现在的实现中，BGP的直连路由是不下发的，因此重分发BGP路由的时候BGP的直连路由是不会被重分发的。R1#shoipospfdatabaseOSPFRouterwithID(.6)(ProcessID1)RouterLinkStates(Are.0)LinkIDADVRouterAgeSeq#CkSumLinkcount.2.27810x800000110xa6482.6.690x800000140xb3282NetworkLinkStates(Are.0)LinkIDADVRouterAgeSeq#CkSum192.168.26.2.215440x800000080xb7d4ASExternalLinkStatesLinkIDADVRouterAgeSeq#CkSumRouteTag192.168.111.0192.168.112.0192.168.125.0192.168.126.0192.168.131.0192.168.132.0.680x800000010xd4f因此需要重分发BGP的直连路由，就必须手工的在OSPF中配置BGP的直连路由。比方：routerospf1network192.168.165.0.255area0network192.168.166.0.255area0重分发IBGP路由C2配置OSPF重分发BGP路由：routerospf1redistributebgp23subnets使用showipospfdatabase可以看到IBGP路由(111.0/112.0/165.0/166.0)是不会重分发给OSPF，而EBGP路由(131.0/132.0)和源发路由(125.0/126.0)会重分发给OSPF。因此可以看出Cisco默认缺省是不重分发IBGP路由的，其它的EBGP路由和源发路由是可以被重分发的。C2#shoipospfdatabaseOSPFRouterwithID(.2)(ProcessID1)RouterLinkStates(Area0)LinkIDADVRouterAgeSeq#ChecksumLinkcount.2.2140x800000100x00AE3F2.6.62150x8000000F0x00C2DE4NetLinkStates(Area0)LinkIDADVRouterAgeSeq#Checksum192.168.26.2.25380x800000080x00B7D4Type-5ASExternalLinkStatesLinkIDADVRouterAgeSeq#ChecksumTag192.168.125.0.2130x800000010x00D6ED0192.168.126.0.2130x800000010x00CBF70192.168.131.0.2130x800000010x00CAF03192.168.132.0.2130x800000010x00BFFA3Cisco可以在BGP模式下使用bgpredistribute-internal命令允许IBGP路由重分发给IGP协议：routerbgp23bgpredistribute-internal此时使用showipospfdatabase可以看到，IBGP路由被重分发到OSPF中：C2#shoipospfdatabaseOSPFRouterwithID(.2)(ProcessID1)RouterLinkStates(Area0)LinkIDADVRouterAgeSeq#ChecksumLinkcount.2.21460x800000100x00AE3F2.6.63480x8000000F0x00C2DE4NetLinkStates(Area0)LinkIDADVRouterAgeSeq#Checksum192.168.26.2.26710x800000080x00B7D4Type-5ASExternalLinkStatesLinkIDADVRouterAgeSeq#ChecksumTag192.168.111.0.240x800000010x00834E1192.168.112.0.240x800000010x0078581192.168.125.0.21450x800000010x00D6ED0192.168.126.0.21450x800000010x00CBF70192.168.131.0.21450x800000010x00CAF03192.168.132.0.21450x800000010x00BFFA3192.168.165.0.240x800000010x001D7F0192.168.166.0.250x800000010x0012890R1配置OSPF重分发BGP路由：routerospf1redistributebgpsubnets使用showipospfdatabase可以看到IBGP路由(125.0/126.0/131.0/132.0)和EBGP路由(111.0/112.0)都重分发给OSPF的(这里没有源发路由)。这就是与Cisco不一致的地方：Cisco缺省不重分发IBGP路由，而Ruijie是重分发所有BGP路由的。R1#shoipospfdatabaseOSPFRouterwithID(.6)(ProcessID1)RouterLinkStates(Are.0)LinkIDADVRouterAg