(Optional) Configuring the LDP Label Policies
Context
The LSR distributes labels to both upstream and downstream LDP peers, which increases the LDP LSP convergence speed. However, receiving and sending Label Mapping messages result in the establishments of a large number of LSPs, which wastes resources. To reduce the number of LSPs and save memory, use the following policies:
Configure the LDP outbound policy.
Configure LDP outbound policy to restrict the sending of Label Mapping messages.
Configure the LDP split horizon policy.
Access devices on the MPLS network have low performance If LDP distributes labels to all peers, a large number of LSPs will be established, which cannot be processed by the LSR. The split horizon policy is recommended.
Procedure
- Configure an outbound LDP policy.
- Perform either of the following steps to apply the outbound
policy that allows Label Mapping messages for specified routes to
be sent to a specified LDP peer:
To configure an outbound policy that allows Label Mapping messages for specified IGP routes to be sent to a specified LDP peer, run outbound peer { peer-id | peer-group peer-group-name | all } fec { none | host | ip-prefix prefix-name }
To configure an outbound policy that allows Label Mapping messages for specified labeled Border Gateway Protocol (BGP) routes to be sent to a specified LDP peer, run outbound peer { peer-id | peer-group peer-group-name | all } bgp-label-route { none | ip-prefix prefix-name }
To apply a policy associated with a single Forwarding Equivalence Class (FEC) range to an LDP peer group or all LDP peers to which the local LSR sends Label Mapping messages, configure either the peer-group peer-group-name or all parameter in the command.
If multiple outbound policies are configured for a specified LDP peer, the first configured one takes effect. For example, the following two outbound policies are configured:
outbound peer 2.2.2.2 fec host outbound peer peer-group group1 fec none
As group1 also contains an LDP peer with peer-id of 2.2.2.2, the following outbound policy takes effect:
outbound peer 2.2.2.2 fec host
If two outbound policies are configured in sequence and the peer parameters in the two commands are the same, the second command overwrites the first one. For example, the following two outbound policies are configured:
outbound peer 2.2.2.2 fec host outbound peer 2.2.2.2 fec none
The second configuration overwrites the first one. This means that the following outbound policy takes effect on the LDP peer with peer-id of 2.2.2.2:
outbound peer 2.2.2.2 fec none
- Perform either of the following steps to apply the outbound
policy that allows Label Mapping messages for specified routes to
be sent to a specified LDP peer:
- Configure an LDP split horizon policy.
