Troubleshooting Gre - 3Com MSR 50 Series Configuration Manual

1600 C 81: GRE C
HAPTER

Troubleshooting GRE

ONFIGURATION
# Configure an IPv4 address for interface Tunnel0.
[RouterB-Tunnel0] ip address 10.1.2.2 255.255.255.0
# Configure the tunnel encapsulation mode.
[RouterB-Tunnel0] tunnel-protocol gre ipv6
# Configure the source address of interface Tunnel0 to be the IP address of
interface Serial 2/1.
[RouterB-Tunnel0] source 2002::2:1
# Configure the destination address of interface Tunnel0 to be the IP address of
interface Serial 2/0 on Router A.
[RouterB-Tunnel0] destination 2002::1:1
[RouterB-Tunnel0] quit
# Configure a static route from Router B through interface Tunnel0 to Group 1.
[RouterB] ip route-static 10.1.1.0 255.255.255.0 tunnel 0
The GRE configurations are relatively simple. The key is to keep the configurations
consistent. Most faults can be pinpointed by using the debugging gre or
debugging tunnel command. This section analyzes only one type of fault, as
shown in Figure
Figure 446 Troubleshoot GRE
IP network
Host A
10.1.1 .1/16
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:
On Router A and Router B, carry out the display ip routing-table command
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in any view respectively. On Router A, observe whether there is a route from
Router A through Tunnel0 to 10.2.0.0/16. On Router B, observer whether there
is a route from Router B through Tunnel0 to 10.1.0.0/16.
For any missing static routes, use the route-static command in system view to
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configure. For example, configure a static route on Router A as follows:
[RouterA] ip route-static 10.2.0.0 255.255.0.0 tunnel 0
446.
Tunnel0
IP network
GRE Tunnel
Router A
Router B
Tunnel 0
IP network
Router C
Host B
10.2.1.1 /16