Configuring LDP inbound FEC filtering

1. In privileged EXEC mode, enter global configuration mode.
   

   device# configure terminal

2. Configure the prefix list to be referenced by the LDP inbound-FEC filter.
   

   device(config)# ip prefix-list list-abc permit 10.20.20.0/24

   In this example, the list-abc prefix list allows the 10.20.20.0/24 route address.
3. Enable MPLS on the device.
   

   device(config)# router mpls

4. Access LDP configuration mode.
   

   device(config-router-mpls)# ldp

5. Configure the LDP inbound FEC filter.
   

   device(config-router-mpls-ldp)# filter-fec-in list-abc

   In this example, LDP accepts inbound FEC 10.20.20.0/24 through the list-abc prefix list and filter out all others FECs.

   

   Note

   When the prefix list referenced by the LDP inbound-FEC filter is configured or changed, all the existing in-bound 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.
6. Verify the inbound FEC-filter configuration.
   

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

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

device# configure terminal
device(config)# ip prefix-list list-abc permit 10.20.20.0/24
device(config)# router mpls
device(config-router-mpls)# ldp
device(config-router-mpls-ldp)# filter-fec-in list-abc