This article describes the Bidirectional Forwarding Detection implementation and examples.
A few words about BFD
Starting from the previous state (BFD neighbor is up) the BFD failure detection in this case is immediately followed by a withdrawal of the failed OSPF neighbour, triggering route reconvergence.
BFD packets seen from the CLI sniffer
FortiGate or VDOM operating in NAT Mode and running OSPF or BGP.
|Step 1 : BFD must be configured globally and per interface (per neighbor if used for BGP)
Default = 50ms ; threshold = 3
FGT # config system settings
FGT(settings) # set bfd enable
FGT # config system interface
FGT(interface) # edit port7
FGT(port7) # set bfd enable
Step 2 : configuration at protocol level
Configuration example at OSPF level
Configuration example at BGP level
Verification with CLI commands
TestFGT_5 # get router info bgp neighbors
BGP neighbor is 192.168.3.254, remote AS 65254, local AS 65250, external link
TestFGT_5 # get router info bfd neighbor
OurAddr NeighAddr LD/RD State Int
192.168.3.250 192.168.3.254 4/1 UP port7