3Com Switch 8800 Configuration Guide Chapter 37 BGP/MPLS VPN Configuration37-90[PE2-bgp] quitConfigure multi-role host feature.Configure a default route pointing to PE1 on CE2.[CE2] ip route-static 0.0.0.0 0.0.0.0 20.1.1.2If routing protocol is used between CE2 and PE1, to avoid routing loop, disable PE1from advertising any route to CE2. In this example, no routing protocol is used betweenPE1 and CE2; so, a static route for PC2 is directly configured on PE1 (you can alsoadopt other similar configuration here).[PE1] ip route-static vpn-instance vpn2 172.16.0.0 16 20.1.1.1Import the route of VPN1 to VPN2 using the VPN Target attribute.[PE1] ip vpn-instance vpn2[PE1-vpn-vpn2] vpn-target 100:1 import-extcommunity37.5 TroubleshootingI. Symptom 1In central server topology networking mode, the local end switch (spoke PE) cannotlearn the routing information of the peer end switch (spoke PE).Solution:z Check whether the BGP adjacent of spoke PE and hub PE is created correctly.z Check whether the routing attributes import/export relation of each VPN-instanceis correct.z Check from the hub PE that whether the routing information between two VPNinstances can be learnt by each other. if not, perform the following operation:check if the EBGP protocol runs between hub PE and hub CE, check whether thepeer peer-address allow-as-loop command is configured between PE and CE.II. Symptom 2PE at the local end can learn private network route of the PE at peer end, but two PEscannot intercommunicate with each other.Solution:z Check whether the loopback interface configured on the PE has the address with32-bit mask.z Check whether the tag of private network route is correct.z Check whether the LDP session is established using the display mpls ldpsession command.z Check whether the LSP tunnel is established using the display mpls lspcommand.
