HP VPN Firewall Appliances VPN Configuration Guide

20
Troubleshooting GRE
The key to configuring GRE is to keep the configurations consistent. Most faults can be located by using
the debugging gre or debugging tunnel command. This section analyzes one type of fault for illustration,
with the scenario shown in Figure 16.
Figure 16 Network diagram
Symptom
The interfaces at both ends of the tunnel are configured correctly and can ping each other, but Host A
and Host B cannot ping each other.
Solution
1. Execute the display ip routing-table command on Firewall A and Firewall C to view whether
Firewall A has a route over tunnel 0 to 10.2.0.0/16 and whether Firewall C has a route over
tunnel 0 to 10.1.0.0/16.
2. If such a route does not exist, execute the ip route-static command in system view to add the route.
Take Firewall A as an example:
[FirewallA] ip route-static 10.2.0.0 255.255.0.0 tunnel 0
IP network
IP network
Firewall A
Firewall B
Firewall C
Host A
Host B
10.1.1.1/16 10.2.1.1/16
Tunnel0 Tunnel0
IP network
GRE Tunnel