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How are you configuring BFD timers?

Using 200 ms / 200 ms / x3 on either metro dark fiber or longhaul waves
(Paris / Frankfurt / Amsterdam) successfully.

Best regards.


2018-03-21 16:11 GMT+01:00 Alex Lembesis <Alex.Lembesis at tevapharm.com>:

> Using 250ms x 3 on fiber connecting Pennsylvania to Florida...
> Best regards,
> Alex
> -----Original Message-----
> From: NANOG [mailto:nanog-bounces at nanog.org] On Behalf Of Jason Lixfeld
> (External)
> Sent: Wednesday, March 21, 2018 9:10 AM
> Subject: How are you configuring BFD timers?
> Hey,
> For those running BFD on your land-based point-to-point links, Iâ??m
> interested in hearing about what factors you consider when deciding how to
> configure your timers and multiplier.
> On paper, BFD between two devices over a local or metro dark fibre or wave
> seems pretty trivial:  Assuming your gear can a) support echo mode b)
> hardware offloads echo processing c) automatically treats echos as vital
> and puts them into the appropriate high priority queue, then setting the
> timers down to their lowest possible values (3ms on some of the gear that
> Iâ??ve seen) and some low multiplier seems more than reasonable.  But?
> From another angle, your link isnâ??t dark fibre or a wave but, for example,
> ethernet over some sort of IP based L2 Transport, and is still a low (sub
> 1ms) one-way latency local or metro link.  How do you set your timers, and
> what do you base that on?
> From yet another angle, what if your link is a long-haul wave, or for that
> matter a wave of any distance that imposes a one-way latency that is higher
> than the minimum tx and rx timers that are supported by your gear?  Weâ??ll
> assume an unprotected wave, because Iâ??m sure if itâ??s protected, you have no
> choice but to consider the one-way latency of the longest of the two
> segments.
> I made some assumptions above about support for echo mode and hardware
> offload, but what if (some of) your gear doesnâ??t support some or all of
> that stuff?  How do you factor your configuration decisions?
> Thanks!
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