3

I would like to know how I can configure Bidirectional Forward Detection on a Virtual-Template interface. Tested on IOSv and IOS-XE (ISR-4451):

router#configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
router(config)#interface Virtual-Template99 type tunnel
router(config-if)#bfd ?
% Unrecognized command
router(config-if)#exit
router(config)#interface tunnel 99
router(config-if)#bfd ?              
  echo      Use echo adjunct as bfd detection mechanism
  interval  Transmit interval between BFD packets
  template  BFD template
router(config-if)#

This is a FlexVPN environment where we want to use BFD.

5

Bidirectional Forward Detection (BFD) has been deactivated on virtual and dialer interfaces on newer IOS and IOS-XE versions.

On earlier releases like IOS-XE 3S, the Cisco IOS software incorrectly allowed configuration of BFD on virtual-template and dialer interfaces; however, BFD functionality on virtual-template and dialer interfaces is not supported. Avoid configuring BFD on virtual-template and dialer interfaces.

That is what the Cisco configuration guide says for BFD on IOS XE:

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_bfd/configuration/xe-3s/irb-xe-3s-book/irb-bi-fwd-det.html

| improve this answer | |
  • Thank you for the explanation. So is there another alternative on how to use BFD in a FlexVPN environment? I found a cisco FlexVPN configuration example with BFD, but they use manually created tunnel interfaces on the hubs, i mean what the heck? cisco.com/c/en/us/support/docs/security/flexvpn/… – Mario Jost Apr 16 '19 at 15:35
  • 1
    @MarioJost I'm really sorry sir, i do not know of any alternatives. – user56700 Apr 16 '19 at 16:36

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