eBGP multihop and Bidirectional Forwarding Detection

[WILLIAM STEGMAN]

Can anyone help clarify if Bidirectional Forwarding Detection (BFD) is compatible with eBGP multihop?  It seems it wouldn't naturally because the physical links are no longer associated with the BGP peer, but I found a document that suggests they can be used together.  Is anyone aware of the twon being used or any documentation that clarifies it further?

http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_bgp/configuration/15-s/irg-15-s-book/irg-multihop-cbit.pdf

thank you,

Bill

[Richard Burts · Accepted solution]

Bill

Page 11 of this NANOG presentation does talk about BFD and EBGP.

https://www.nanog.org/meetings/nanog45/presentations/Monday/Scholl_BFD_N45.pdf

Also RFC 5882 explicitly discusses using BFD with EBGP.

http://tools.ietf.org/html/rfc5882

HTH

Rick

[WILLIAM STEGMAN]

I seem to keep finding contradictions on the support.  The RFC states its support, but it looks like it may come down to vendor and OS version.

This states it's not supported on the ASR1000

http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_bgp/configuration/xe-3s/asr1000/irg-xe-3s-asr1000-book/irg-sup-for-bfd.html#GUID-F4FF8AFE-4DA4-441B-967C-2ABE75450B87

"BFD works only for directly-connected neighbors. BFD neighbors must be no more than one IP hop away. Multihop configurations are not supported. "

but it is on the ASR 901

http://www.cisco.com/c/en/us/td/docs/wireless/asr_901/Configuration/Guide/config_guide/multihopbfd.html#wp1087195

and Juniper seems to support it

http://www.juniper.net/techpubs/en_US/junos12.1/topics/topic-map/bgp-bfd.html

[Richard Burts]

Bill

It does not surprise me that there are inconsistencies in support for this new feature and that it does come down to vendor and OS version. Your original question was whether BFD is compatible with EBGP multihop. And the answer for now seems to be "sometimes it is". But we will need to read release notes carefully to determine whether a particular platform and version of OS do support it.

HTH

Rick