An Interface Fails to Communicate with the Peer Device After IP Unnumbered Is Configured

Procedure

1. Check whether the IP unnumbered interface is a VLANIF or tunnel interface.
   

   Currently, only VLANIF or tunnel interfaces on the device can borrow IP addresses from other interfaces. Ethernet interfaces cannot borrow IP addresses from other interfaces.

   If IP unnumbered is configured in the VLANIF or tunnel interface view, go to step 2.

2. Check whether the numbered interface specified in the IP unnumbered interface configuration has an IP address.

   Run the display this command in this interface view to check whether the interface has an IP address.

   • If ip address x.x.x.x is not displayed, run the ip address ip-address { mask | mask-length } command in this interface view to configure an IP address.
   • If ip address x.x.x.x is displayed, go to step 3.

3. Check whether a static route to the peer device is configured on the local device.
   

   The IP unnumbered interface cannot run dynamic routing protocols because it does not have an IP address itself. To enable the interface to communicate with the peer device, configure a static route to the peer device.

   Run the display ip routing-table command to check whether a static route to the peer device is configured. In the routing table, static routes are identified by Static in the Proto field.

   • If no static route in the routing table matches the destination IP address on the peer device, run the ip route-static ip-address { mask | mask-length } interface-type interface-number [ nexthop-address ] command to configure a static route.
   • If the routing table contains a static route matching the destination IP address on the peer device and the outbound interface is the unnumbered interface, go to step 4.

4. Collect the following information and contact technical support personnel:
   • Results of the preceding troubleshooting procedure
   • Configuration file, logs, and alarms of the local device