Overview of ORF Support for BGP Labeled Unicast
In earlier releases, BGP does not negotiate the labeled IPv4 unicast address family separately from the unlabeled IPv4 unicast address family. This results in outbound route filtering (ORF) negotiation failure when peering with other operating systems in the network.
Starting from Cisco IOS XE Cupertino 17.8.1, BGP uses the label-unicast unique mode. Unlabeled and labeled unicast BGP-prefixed sessions are treated separately. This improves the interoperability with other operating systems.
The BGP prefix-based ORF is enabled through the advertisement of ORF capabilities to peer routers. The advertisement of the ORF capability indicates that a BGP peer accepts a prefix list from a neighbor and applies the prefix list to locally configured ORFs (if any exist).
This feature uses BGP ORF send and receive capabilities to minimize the number of BGP updates that are sent between BGP peers. It can also filter out unwanted routing updates at the source to reduce the amount of system resources that are required for generating and processing routing updates.