The Bidirectional Forward Detection (BFD) protocol is a simple hello mechanism that detects failures in a network. Hello packets are sent at a regular specified intervals. A neighbor failure is detected when the router stops recieving a reply after the specified interval. The failure detection timers for BFD have shorter time limits than default failure detection mechanisms, providing faster detection. These timers are also adaptive and can be adjusted to be more or less aggressive. For example, the timers can adapt to a higher value if the adjacency fails, or a neighbor can negotiate a higher value for a timer than the one configured. This KB explains how to configure and verify BFD under OSPF protocol.

Configuration:

1. Configure the bfd timer minimum-interval to specify the transmit and receive intervals on the interface where the ospf neighbor is connected                 

2. Configure the multiplier number which is the number of hello packets not received by a neighbor that causes the originating interface to be declared down

             [edit protocols ospf area 0.0.0.0]
       user@switch# set interface ge-0/0/2.0 bfd-liveness-detection multiplier 3
  

        3.  Configure BFD sessions only for the OSPF neighbors with full neighborship adjacency. The default behavior is to establish BFD sessions for all OSPF neighbors.


This feature is applicable only from JUNOS 9.5 release and higher.