LDP Autoconfiguration

LDP Autoconfiguration

By default, no LDP is enabled on any interfaces. LDP is enabled on per-interface using mpls ip command manually. Instead of going to every interface and enabling LDP, there is another way to enable on all OSPF/ISIS enabled interfaces.

Pre-requisite: LDP should be enabled globally using mpls ip command for LDP Autoconfiguration.

From OSPFrouter configuration mode, use mpls ldp autoconfig [area area-id] command.

From ISIS router configuration mode, use mpls ldp autoconfig [level-1 | level-2] command.

To disable LDP on a particular interface, use no mpls ldp igp autoconfig from interface configuration mode.

To view if LDP is enabled manually on per-interface basis or auto-configured, use show mpls ldp discovery or show mpls interfaces detail command. "Interface Config" indicates LDP was enabled from the interface using mpls ip command. "IGP Config" indicates LDP was enabled through the router configuration mode using mpls ldp autoconfig command.

Consider the following-

R1 and R2 routers are connected via point-to-point serial link. LDP is enabled from the interface using mpls ip command.

R1# show mpls ldp discovery detail

Local LDP Identifier:

1.1.1.1:0

Discovery Sources:

Interfaces:

Serial0/0 (ldp): xmit/recv

Enabled: Interface config

Hello interval: 5000 ms; Transport IP addr: 1.1.1.1

LDP Id: 2.2.2.2:0

Src IP addr: 10.1.1.2; Transport IP addr: 2.2.2.2

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

Reachable via 2.2.2.2/32

R1# show mpls interfaces detail

Interface Serial0/0:

IP labeling enabled (ldp):

Interface config

LSP Tunnel labeling not enabled

BGP tagging not enabled

Tagging operational

Fast Switching Vectors:

IP to MPLS Fast Switching Vector

MPLS Turbo Vector

MTU = 1500

R1# show ip ospf mpls ldp interface serial 0/0

Serial0/0

Process ID 1, Area 0

LDP is not configured through LDP autoconfig

LDP-IGP Synchronization : Not required

Holddown timer is disabled

Interface is up

Now, LDP autoconfiguration is performed as below-

R1# show mpls ldp discovery detail

Local LDP Identifier:

1.1.1.1:0

Discovery Sources:

Interfaces:

Serial0/0 (ldp): xmit/recv

Enabled: IGP config;

Hello interval: 5000 ms; Transport IP addr: 1.1.1.1

LDP Id: 2.2.2.2:0

Src IP addr: 10.1.1.2; Transport IP addr: 2.2.2.2

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

Reachable via 2.2.2.2/32

R1# show mpls interfaces detail

Interface Serial0/0:

IP labeling enabled (ldp):

IGP config

LSP Tunnel labeling not enabled

BGP tagging not enabled

Tagging operational

Fast Switching Vectors:

IP to MPLS Fast Switching Vector

MPLS Turbo Vector

MTU = 1500

R1# show ip ospf mpls ldp interface serial 0/0

Serial0/0

Process ID 1, Area 0

LDP is configured through LDP autoconfig

LDP-IGP Synchronization : Not required

Holddown timer is disabled

Interface is up