Bidirectional Forwarding Detection

Bidirectional Forwarding Detection (BFD) is used to detect faults between two routers across a link, even if the physical link does not support failure detection. Even in cases where physical link issues occur and are detected, BFD can coordinate reaction to these failures rather than each component relying on its own failure detection methods.

FRR uses UDP as a transport for BFD between directly connected routers (single hop/next hop) as described in RFC 5880 and RFC 5881.

Each BFD session monitors one link. Multiple BFD sessions are necessary to detect faults on multiple links. BFD sessions must be manually configured between endpoints as there is no method for automated discovery.

When using BFD, both endpoints transmit “Hello” packets back and forth between each other. If these packets are not received within the expected time frame the link is considered down. Links may also be administratively configured as down and will not recover until manually changed.

FRR currently supports BFD integration with BGP, OSPF, and OSPF6.

BFD is configured at Services > FRR BFD.

The BFD tab contains only the master Enable switch for BFD.


The BFD implementation in FRR does not currently support authentication.