R3721-F3210-F3171-HP High-End Firewalls VPN Configuration Guide-6PW101

19
Displaying and maintaining GRE
Task Command Remarks
Display information
about a specific or all
tunnel interfaces.
display interface [ tunnel ] [ brief [ down ] ] [ | { begin |
exclude | include } regular-expression ]
display interface tunnel number [ brief ] [ | { begin |
exclude | include } regular-expression ]
Available in any view
Display IPv6
information about a
tunnel interface.
display ipv6 interface tunnel [ number ] [ brief ] [ | { begin
| exclude | include } regular-expression ]
Available in any view
Troubleshooting GRE
NOTE:
In this example, either Router A or Router C is the firewall.
The key to configuring a GRE tunnel is to keep the configurations consistent on both ends of the tunnel.
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 Troubleshooti
ng GRE
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
• Execute the display ip routing-table command on Router A and Router C to view whether Router A
has a route over tunnel0 to 10.2.0.0/16 and whether Router C has a route over tunnel0 to
10.1.0.0/16.
• If such a route does not exist, execute the ip route-static command in system view to add the route.
Take Router A as an example:
[RouterA] ip route-static 10.2.0.0 255.255.0.0 tunnel 1
IP network
IP network
Router A
Router B
Router C
Host A
Host B
10.1.1.1/16 10.2.1.1/16
Tunnel0 Tunnel0
IP network
GRE Tunnel