LDP Auto configuration

LDP have a feature called auto configuration. This feature will allow you to enable mpls on all the interface which is running IGP protocol. We don’t need to provide individual interface mpls ip command.

To enable this and try this feature am going to remove MPLS command on R3 and going to configure  MPLS via autoconfig feature.

R3(config)#int s1/0

R3(config-if)#no mpls ip

R3(config)#int s1/1

R3(config-if)#no mpls ip

Lets verify are we running MPLS

R3#sh mpls interfaces

Interface              IP            Tunnel   Operational

We are not. Now lets autoconfig LDP on R3.

R3(config)#router ospf 1

R3(config-router)#mpls ldp autoconfig area 0                      { This autoconfig will work only on OSPG IGP protocol }

R3#sh mpl ldp discovery

 Local LDP Identifier:

    3.3.3.3:0

    Discovery Sources:

    Interfaces:

        Serial1/0 (ldp): xmit/recv

            LDP Id: 2.2.2.2:0

        Serial1/1 (ldp): xmit/recv

            LDP Id: 4.4.4.4:0

R3#sh mpl ldp discovery detail

 Local LDP Identifier:

    3.3.3.3:0

    Discovery Sources:

    Interfaces:

        Serial1/0 (ldp): xmit/recv

            Enabled: IGP config; ==========================> MPLS is enabled via IGP.

            Hello interval: 5000 ms; Transport IP addr: 3.3.3.3

            LDP Id: 2.2.2.2:0

              Src IP addr: 10.0.0.5; Transport IP addr: 2.2.2.2

              Hold time: 15 sec; Proposed local/peer: 15/15 sec

              Reachable via 2.2.2.2/32

If we want to remove one particular interface within this autoconfig MPLS. Go to that particular interface and issues this command

R3(config)#int s1/1

R3(config-if)#no mpls ldp igp autoconfig

R3#sh mpl ldp discovery

 Local LDP Identifier:

    3.3.3.3:0

    Discovery Sources:

    Interfaces:

        Serial1/0 (ldp): xmit/recv

            LDP Id: 2.2.2.2:0

See only LDP peer to R4 is removed.