Network Router User Manual

2 GRE troubleshooting
Nortel Secure Router 8000 Series
Troubleshooting - VPN
2-4 Nortel Networks Inc. Issue 5.3 (30 March2009)
2.2 Troubleshooting GRE
This section covers the following topics:
z
Typical networking
z
Configuration notes
z
Troubleshooting flowchart
z
Troubleshooting procedure
2.2.1 Typical networking
Figure 2-3 Typical GRE networking diagram
Nortel1
Tunnel1/0/0
30.1.1.1/24
Tunnel1/0/0
30.1.1.2/24
10.2.1.1/2410.1.1.1/24
POS1/0/0
10.1.1.2/24
POS1/0/0
100.1.1.1/24
POS1/0/0
100.1.1.2/24
POS1/0/0
100.2.1.2/24
POS2/0/0
100.2.1.1/24
POS2/0/0
10.2.1.2/24
PC1
PC2
Tunnel
Nortel3
Nortel2
As shown in
Figure 2-3:
z
A GRE tunnel is set up between Nortel 1 and Nortel 2.
z
Nortel 1 and Nortel 3 directly connect.
z
Nortel 2 and Nortel 3 directly connect.
2.2.2 Configuration notes
If you create a tunnel interface on a distributed device, configure the same slot numbers for the tunnel
interface and the tunnel source. Use the slot that sends out GRE packets to improve the forwarding
efficiency.
Item Subitem Notes
Configuring the
encapsulation
mode on both
ends of a tunnel
Tunnel
protocol
The encapsulation mode must be the same on both
ends of a tunnel.