Seamless Bidirectional Forwarding Detection (S-BFD) [RFC 7880
] defines a simplified mechanism to use Bidirectional Forwarding Detection (BFD) [RFC 5880
] with large portions of negotiation aspects eliminated, thus providing benefits such as quick provisioning as well as improved control and flexibility to network nodes initiating the path monitoring.
For the monitoring of a service path end to end via S-BFD, the headend node (i.e., Initiator) needs to know the S-BFD Discriminator of the destination/tail-end node (i.e., Responder) of that service. The link-state routing protocols (IS-IS [RFC 7883
] and OSPF [RFC 7884
]) have been extended to advertise the S-BFD Discriminators. With this, an Initiator can learn the S-BFD Discriminator for all Responders within its IGP area/level or optionally within the domain. With networks being divided into multiple IGP domains for scaling and operational considerations, the service endpoints that require end-to-end S-BFD monitoring often span across IGP domains.
BGP - Link State (BGP-LS) [RFC 7752
] enables the collection and distribution of IGP link-state topology information via BGP sessions across IGP areas/levels and domains. The S-BFD Discriminator(s) of a node can thus be distributed along with the topology information via BGP-LS across IGP domains and even across multiple Autonomous Systems (ASes) within an administrative domain.
This document defines extensions to BGP-LS for carrying the S-BFD Discriminators' information.