3Com Switch 8800 Family Configuration Guide

Troubleshooting BGP/MPLS VPN Configuration 599
# Configure a default route pointing to PE1 on CE2.
[CE2] ip route-static 0.0.0.0 0.0.0.0 20.1.1.2
# Configure a multiple-role host route on PE1.
[PE1] ip route-static vpn-instance vpn1 172.16.0.0 16 vpn2 20.1.1.1
# Import the route of VPN1 to VPN2 using the RT attribute.
[PE1] ip vpn-instance vpn2
[PE1-vpn-vpn2] vpn-target 100:1 import-extcommunity
Troubleshooting
BGP/MPLS VPN
Configuration
Symptom 1
In central server topology networking mode, the local end switch (spoke PE)
cannot learn the routing information of the peer end switch (spoke PE).
Solution:
■ Check whether the BGP adjacent of spoke PE and hub PE is created correctly.
■ Check whether the routing attributes import/export relation of each
VPN-instance is correct.
■ Check from the hub PE that whether the routing information between two
VPN instances 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 the peer peer-address allow-as-loop command is configured
between PE and CE.
Symptom 2
PE at the local end can learn private network route of the PE at peer end, but two
PEs cannot intercommunicate with each other.
Solution:
■ Check whether the loopback interface configured on the PE has the address
with 32-bit mask.
■ Check whether the tag of private network route is correct.
■ Check whether the LDP session is established using the display mpls ldp
session command.
■ Check whether the LSP tunnel is established using the display mpls lsp
command.
Symptom 3
In Hub&Spoke networking mode, spoke PE cannot learn the private networking
route of Hub PE.
Solution:
■ Check whether the LSP tunnel is established using the display mpls lsp
command.