10.128.159.128/25 IBGP 255 0 RD 1.1.1.1 GigabitEthernet0/0/0 由于2台PE之间是直接,2条vpn的路由经过的路径是一样的,正常在PE2上学到的这2条路由的cost值应该是一样的,但在路由表中发现却不一样,难道在PE2上有2条10.128.159.128/25网段的路由,进一步查看PE2上收到的vpna路由: [PE2]disp bgp vpnv4 vpn-instance vpna routing-table BGP Local router ID is 2.2.2.2 Status codes: * - valid, > - best, d - damped, h - history, i - internal, s - suppressed, S - Stale Origin : i - IGP, e - EGP, ? - incomplete VPN-Instance vpna, Router ID 2.2.2.2: Total Number of Routes: 719 Network NextHop MED LocPrf PrefVal Path/Ogn *>i 10.128.159.128/25 1.1.1.1 0 100 0 ? * i 1.1.1.1 15 100 0 ? 通过查看vpna路由发现此网段确实有2条路由,而在路由表中优选了cost值小的路由,此路由是从何而来? 查看2台PE的配置发现vpna的RT设置中同时接收了vpnb的路由,此路由是从vpnb学习到的?在PE1下查看vpnb路由表确实发现也存在此网段的路由: [PE1]dis ip routing-table vpn-instance vpnb Route Flags: R - relay, D - download to fib ------------------------------------------------------------------------------ Destination/Mask Proto Pre Cost Flags NextHop Interface 10.128.159.128/25 Static 60 0 RD 1.1.14.2 GigabitEthernet0/0/2 为了进一步确认是否为vpnb下的路由,再次在PE2上查看路由的详细信息,发现此路由的标签值为1028,通过标签值对比可以确定在PE2上学习到的10.128.159.128/25网段路由是vpnb引进的而不是vpna本身的路由。
[PE2]dis ip routing-table vpn-instance vpna 10.128.159.128 verbose Route Flags: R - relay, D - download to fib ------------------------------------------------------------------------------ Routing Table : vpna Summary Count : 1 Destination: 4.4.4.0/24 Protocol: IBGP Process ID: 0 Preference: 255 Cost: 0 NextHop: 1.1.1.1 Neighbour: 1.1.1.1 State: Active Adv Relied Age: 00h12m44s Tag: 0 Priority: low Label: 1028 QoSInfo: 0x0 IndirectID: 0x3 RelayNextHop: 1.1.12.1 Interface: GigabitEthernet0/0/0 TunnelID: 0x1 Flags: RD 而在PE1上查看vpna和vpnb为此网段分配的标签值为: <PE1>dis mpls lsp verbose ------------------------------------------------------------------------------- LSP Information: BGP LSP ------------------------------------------------------------------------------- No : 3 VrfIndex : vpna RD Value : 0:0 Fec : 4.4.4.0/24 Nexthop : ------- In-Label : 1026 Out-Label : NULL In-Interface : ---------- Out-Interface : ---------- LspIndex : 4098 Token : 0x0 LsrType : Egress Outgoing token : 0x0 Label Operation : POP Mpls-Mtu : ------ TimeStamp : 1475sec FrrToken : 0x0 FrrOutgoingToken : 0x0 BGPKey : ------- BackupBGPKey : ------- FrrOutLabel : ------- No : 5 VrfIndex : vpnb RD Value : 0:0 Fec : 4.4.4.0/24 Nexthop : ------- In-Label : 1028
Out-Label : NULL In-Interface : ---------- Out-Interface : ---------- LspIndex : 4100 Token : 0x0 LsrType : Egress Outgoing token : 0x0 Label Operation : POP Mpls-Mtu : ------ TimeStamp : 1480sec FrrToken : 0x0 FrrOutgoingToken : 0x0 BGPKey : ------- BackupBGPKey : ------- |