Panasonic NN46240-710 - Manual (Page 68)

2 GRE troubleshooting
Nortel Secure Router 8000 Series
_________ Troubleshooting - VPN
Summary
Because the network layer protocols of the tunnel interfaces on both ends of the GRE tunnel are
up does not guarantee that the GRE tunnel is configured correctly. Two additional requirements
exist:
• The GRE keys on both ends are consistent.
• The route to the peer tunnel interface is configured on both ends.
2.3.2 PCs cannot ping through each other although tunnel
interfaces on two ends can ping each other successfully
Fault symptom
Figure 2-6 Networking diagram of the GRE troubleshooting II
Routers
PC1
10.1.1.1/16
Tunnel1/0/0 Tunnel2/0/0
Nortell Nortel2 PC2
10.2.1.1/16
In Figure 2-6, the interfaces on both ends of the tunnel are configured correctly and they can
ping each other successfully. However, PC1 and PC2 cannot ping through each other.
Fault analysis
The possible causes are:
• No route to PC1 exists on Nortel 1.
• No route to PC2 exists on Nortel 2.
• PC1 does not specify Nortel 1 as its default gateway.
• PC2 does not specify Nortel 2 as its default gateway.
Use the display ip routing-table command on Nortel 1 and Nortel 2 to view:
• Whether a route passes through Tunnel 1/0/0 to 10.2.0.0/16 on Nortel 1.
• Whether a route passes through Tunnel 2/0/0 to 10.1.0.0/16 on Nortel 2.
If the two routes do not exist, use the ip route-static command in the system view to configure
them.
For example, on Nortel 1, the configuration command is [Nortel1] ip route-static 10.2.0.0
255.255.0.0 tunnel 1/0/0.
After you complete the configuration, ping the peer tunnel on Nortel 1 and Nortel 2 to receive
the response packets.
2-14 Nortel Networks Inc. Issue 5.3 (30 March2009)