3Com Switch 8800 Advanced Software V5 Configuration Guide

404 CHAPTER 33: TUNNELING CONFIGURATION
Troubleshooting
Tunneling
Configuration
Symptom: After the configuration of related parameters such as tunnel source
address, tunnel destination address, and tunnel type, the tunnel interface is still
not up.
Solution: Follow the steps below:
1 The common cause is that the physical interface of the tunnel source is not up.
Use the display interface tunnel or display ipv6 interface tunnel commands
to view whether the physical interface of the tunnel source is up or down. If the
physical interface is down, use the debugging tunnel event command in user
view to view the cause. For related commands and description of debugging
information, refer to the Switch 8800 Command Reference Guide.
2 Another possible cause is that the tunnel destination is unreachable. Use the
display ipv6 routing-table or display ip routing-table command to view
whether the tunnel destination is reachable. If no routing entry is available for
tunnel communication in the routing table, configure related routes.