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Tunnel Interface Alternates Between Up and Down States
Fault Description
After a GRE tunnel is configured, the tunnel interface alternates between Up and Down states.
Troubleshooting Procedure
Run the display fib destination-address command in any view multiple times to check whether the outbound interface in the FIB entry to the specified destination network segment changes. For example, the command outputs are displayed as follows:
<Huawei> display fib 10.2.1.0
Route Entry Count: 1
Destination/Mask Nexthop Flag TimeStamp Interface TunnelID
10.2.1.0/24 10.3.1.2 SU t[631838] Tun0/0/1 0x0
<Huawei> display fib 10.2.1.0
Route Entry Count: 1
Destination/Mask Nexthop Flag TimeStamp Interface TunnelID
10.2.1.0/24 1.1.1.2 GSU t[631840] GE1/0/0 0x0
The command outputs show that the outbound interface to 10.2.1.0 changes. As a result, the tunnel interface flaps.
If the outbound interface changes, adjust the network topology to ensure that the outbound interface is not a GRE tunnel interface. For VLL, PWE3, and BGP/MPLS IP VPN services, you are advised to run the tunnel-policy (system view) command to select the GRE tunnel by tunnel policy.