(Optional) Configuring the Inbound LDP Policy

An inbound LDP policy can be configured to prevent the establishment of unwanted LSPs, efficiently using memory.

Context

An LSR is usually able to receive Label Mapping messages from all LDP peers, speeding up LDP LSP convergence. This leads to a great number of unwanted LSPs to be established, wasting resources. An inbound LDP policy can be configured to reduce the number of Label Mapping messages to be received. The inbound LDP policies help reduce the number of unwanted LSPs to be established and efficiently use memory.

The inbound LDP policy helps an LSR provide a specific function based on one of the following parameters:

none: filters out all forwarding equivalence classes (FECs). A specified peer does not receive any IGP route-based Label Mapping messages sent by peers.
host: allows FECs for host routes to pass. A specified peer receives host route-based Label Mapping messages sent by peers.
ip-prefix: allows only the FEC for a specified IP prefix to pass. A specified peer receives IP prefix-based Label Mapping messages sent by peers.

Procedure

Run system-view
The system view is displayed.
Run mpls ldp
The MPLS-LDP view is displayed.
Run ipv4-family
The MPLS LDP IPv4 view is displayed.
Run inbound peer { peer-id | peer-group peer-group-name | all } fec { none | host | ip-prefix prefix-name }
An inbound policy for allowing the local LSR to receive label mapping messages from a specified LDP peer for a specified IGP route is configured.

To apply a policy associated with a single FEC range to an LDP peer group or all LDP peers from which the local LSR receives Label Mapping messages, configure either the peer-group peer-group-name or all parameter in the command.
If multiple inbound policies are configured for a specified LDP peer, the first configured one takes effect. For example, the following two inbound policies are configured:
```
inbound peer 2.2.2.2 fec host
inbound peer peer-group group1 fec none
```
As group1 also contains an LDP peer with peer-id of 2.2.2.2, the following inbound policy takes effect:
```
inbound peer 2.2.2.2 fec host
```
If two inbound 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 inbound policies are configured:
```
inbound peer 2.2.2.2 fec host
inbound peer 2.2.2.2 fec none
```
The second configuration overwrites the first one. This means that the following inbound policy takes effect on the LDP peer with peer-id of 2.2.2.2:
```
inbound peer 2.2.2.2 fec none
```
If an inbound policy for all peers is configured and another inbound policy for a specific peer or peer group is configured, the previous policy has a higher priority, and the later policy does not take effect. For example:
```
inbound peer all fec none
inbound peer 2.2.2.2 fec host
```
The following inbound policy takes effect:
```
inbound peer all fec none
```
MPLS and MPLS LDP must be enabled globally before an inbound policy is configured.

To delete all inbound policies simultaneously, run the undo inbound peer all command.
Run commit
The configuration is committed.