Use the following procedure to configure BFD on a Fabric Extend Tunnel.
enable
configure terminal
router bfd enable
ip bfd enable
ip bfd enable
logical-intf isis <1–255> bfd enable
Enable BFD on a Fabric Extend tunnel:
Switch:1>enable Switch:1#config terminal Enter configuration commands, one per line. End with CNTL/Z. Switch:1(config)#router bfd enable Switch:1(config)#interface loopback 1 Switch:1(config-if)#ip bfd enable Switch:1(config-if)#logical-intf isis 1 Switch:1(config-isis-1-1.2.3.5)#bfd enable