Re: How are you configuring BFD timers?

[Ben Bartsch <uwcableguy () gmail com>]

No sure if this link has been provided yet, but this is how I learned BFD -
https://supportforums.cisco.com/t5/service-providers-documents/bfd-support-on-cisco-asr9000/ta-p/3153191

My only experience with BFD has been with short paths using grey optics and
interstate DWDM spans.  I found 3x50ms echo mode worked well, but you need
to watch out for QoS on the remote side as the packet that hairpins back to
the sender is subject to queuing.  As the link becomes saturated, the BFD
packet goes in the queue with everyone else as the far end router hairpins
it and can cause a false link down condition if it goes in the bit bucket.
I saw timers as low as 3x10ms echo mode with QoS work really well on a
strictly ASR9k network.

I never tried to run it on bundle links or over layer 2.

I did try to run it on some Dell Z9100 and S4048 boxes running FTOS 9 and
it failed miserably even with very conservative timers.  I haven't had a
chance to test it with IPI OcNOS 1.3.3 on the same boxes, or with JunOS.

On Thu, Mar 22, 2018 at 3:16 PM, Scott Weeks <surfer () mauigateway com> wrote:

> --- saku () ytti fi wrote:
> From: Saku Ytti <saku () ytti fi>
>
> ...but I have far more BFD caused problems than BFD solved
> problems, spanning multiple vendors. (CAT7600, ASR9k, MX).
> ----------------------------------------
>
>
> Yes, that's for sure.  Also, it's hard to scale when you're
> tweaking knobs on each session trying to get the time down
> w/o causing failure unnecessarily.
>
> scott