The Local Tunnel Interface Fails to Ping the IP Address of the Remote Tunnel Interface

Procedure

• When the network layer protocol of one or both ends of a tunnel is Down
  1. Check that interfaces on both ends of the tunnel use the same tunnel encapsulation mode.

     Run the display this interface command in the tunnel interface view on both ends of the tunnel to check whether interfaces on both ends use the same tunnel encapsulation mode. If Tunnel protocol/transport GRE/IP is displayed, the tunnel encapsulation mode is GRE.

     • If the two interfaces use different tunnel encapsulation modes, run the tunnel-protocol command in the tunnel interface view to reconfigure the tunnel encapsulation mode of one interface to be the same as that of the other interface.

       

       After reconfiguring the tunnel encapsulation mode, reconfigure the tunnel source and destination addresses because configurations of the original source and destination addresses are lost.

     • If the two interfaces use the same tunnel encapsulation mode, go to step 2.

  2. Check that an IP address, a tunnel source address (or interface), and a tunnel destination address are configured for interfaces on both ends of the tunnel.

     Check whether the local tunnel source address (or interface) is the peer tunnel destination address and the local tunnel destination address is the peer tunnel source address (or interface). If not, no tunnel can be established between the two interfaces. A tunnel source address (or interface) and a tunnel destination address uniquely identify a tunnel.

     Run the display this command in the tunnel interface view to check the interface configuration. Ensure that the local tunnel source address (or interface) is the peer tunnel destination address and the local tunnel destination address is the peer tunnel source address.

     • If the tunnel source (or interface) and destination addresses are incorrect, run the source and destination commands in the tunnel interface view to reconfigure the tunnel source (or interface) and destination addresses.
     • If the tunnel source (or interface) and destination addresses are correct, go to step 3.

  3. Check that there are reachable routes between the tunnel source and destination addresses.

     If the interface configurations on both ends are correct but the tunnel status is still Down, check whether there are reachable routes between interfaces on both ends of the tunnel.

     • If the tunnel is established between two indirectly connected interfaces, check whether there are reachable routes between the two interfaces.

     • If the tunnel is established between two directly connected interfaces, a direct route exists.

     Run the display ip routing-table command to view the IP routing table. If the IP routing table is correct, run the display fib command to check the forwarding table (FIB table) and check whether data is correctly forwarded.

     If there is no reachable route between the tunnel source (or interface) and destination addresses, configure static routes between the tunnel source and destination addresses or configure a dynamic routing protocol to calculate reachable routes.

• When the network layer protocol of interfaces on both ends of a tunnel is Up

  If the network protocol status of the two interfaces is Up but they cannot ping each other, check whether their IP addresses are on the same network segment. If the IP addresses are on different network segments, configure static routes between the two devices or configure a dynamic routing protocol to calculate reachable routes.