Configuring global LDP outbound FEC filtering

MPLS and LDP protocol must be enabled on the router to use LDP outbound FEC filtering.

To enable global LDP outbound FEC filtering, perform the following steps.

In privileged EXEC mode, enter global configuration mode.
```
device# configure terminal
```
Configure the prefix list to be referenced by the LDP outbound FEC filter to deny an address.
```
device(config)# ip prefix-list list-out deny 10.40.40.0/24
```
In this example, the list-out prefix list prevents the 10.40.40.0/24 route address.
Configure the prefix list to allow all other FECs to all neighbors.
```
device(config)# ip prefix-list list-out permit permit 0.0.0.0/0 ge 32
```
In this example, the list-out prefix list allows the default route address.
Enable MPLS on the device.
```
device(config)# router mpls
```
Access LDP configuration mode.
```
device(config-router-mpls)# ldp
```
Configure the LDP outbound FEC filter.
```
device(config-router-mpls-ldp)# filter-fec-out list-out
```
In this example, LDP prevents advertisement of FEC 10.40.40.0/24 through the list-out prefix list and allows all others FECs to all neighbors.

Note
When the prefix list referenced by the LDP outbound FEC filter is configured or changed, all the existing outbound FECs and received later are subject to the changed prefix list. There is a configurable delay between changing the prefix list and the changed prefix list taking effect on LDP FEC filter configuration.

Verify the outbound FEC-filter configuration.

device(config-router-mpls-ldp)# do show running-config router mpls ldp
router mpls
 ldp
  ....
  filter-fec-out list-out
 !
!

The following example shows the previous steps to configure the LDP outbound FEC filter.

device# configure terminal
device(config)# ip prefix-list list-out deny 10.40.40.0/24
device(config)# ip prefix-list list-out permit 0.0.0.0/0 ge 32
device(config)# router mpls
device(config-router-mpls)# ldp
device(config-router-mpls-ldp)# filter-fec-out list-out