3Com Switch 8800 Family IPsec Module Configuration and Command reference Guide

GRE Troubleshooting 141
Figure 36 Troubleshooting example of GRE
Symptom 1: The interfaces at both ends of the Tunnel are correctly configured and
both ends of the Tunnel can "ping" each other successfully, but PC A and PC B fail
to do so.
Troubleshooting: Perform the following steps:
■ In user view, perform the display ip route command on 3Com1 and 3Com2
respectively, making sure there is the route from interface Tunnel1/0/0 to
10.2.0.0/16 on 3Com1, and the route from interface Tunnel 2/0/0 to
10.1.0.0/16 on 3Com2.
■ If the needed static route do not exist in the output information of the above
step, perform the ip route command in system view to add it. Taking 3Com1
for example, make the following configuration:
<3Com1> system-view
[3Com1] ip route-static 10.2.0.0 255.255.0.0 Tunnel 0
PC A
10.1.1.1/16
PC B
10.2.1.1/16
Ethernet1/0/0 Ethernet2/0/1
Tunnel
Switch88001 Switch88003
Switch88002
Tunnel1/0/0 Tunnel2/0/0