Dynamically Associating the Shared IP Interface with the Layer 2 Interface

You can specify that the shared IP interface dynamically tracks a next hop using the ip share-nexthop command. If the next hop changes, the shared IP interface moves to the new layer 2 interface associated with the IP interface toward the new next hop.

The shared interface is operationally up when the layer 2 interface associated with the specified next hop is operationally up. However, if the layer 2 interfaced associated with the specified next hop is an MPLS next hop (for example, an RSVP or LDP tunnel), the shared interface remains operationally down.

If you issue the ip share-nexthop command on a shared IP interface, the shared interface cannot dynamically track the next hop for the specified destination if the next-hop IP address is resolvable over MPLS.

If you specify a virtual router, the command fails if the VR does not already exist. If you do not specify a VR, the current VR is assumed.

Note: All IP configurations will be removed from the interface when you issue the no ip interface command in Interface Configuration mode. You cannot issue the ip share-interface command for the IP shared interface if the ip share-nexthop command is issued on the IP shared interface.

To specify that the shared IP interface dynamically tracks a next hop:

• Issue the ip share-nexthop command in Interface Configuration mode.
  host1:vr-a:vrf-1(config-if)#ip share-nexthop 10.0.0.1

  Use the no version to halt tracking of the next hop.

Related Documentation

• Shared IP Interfaces Overview
• IP Shared Interface Statistics Overview
• Monitoring IP Shared Interfaces
• ip share-interface
• ip share-nexthop
• no ip interface