Re: I-D Action: draft-ietf-rtgwg-ordered-fib-07.txt

[Saku Ytti <[e-mail]>]

On 9 September 2012 22:45, Stewart Bryant <[e-mail]> wrote:

> The expected use of this technology in the failure case
> is in conjunction with IPFRR where following a protected
> failure, and in the absence of a convergence control
> technology, microloops may form and/or the repair
> may be staved.

If failure cannot be IPFRR protected, conventional FIB insertion would be used?

> Note not only do you need to learn of the failure
> and compute the new SPF, you also need to update the
> FIB. The FIB update time can be the dominant factor in
> re-convergence.

Yes, certain modern chassis based L3 switch can literally take >hour
in real network to update its FIB.

I once thought of sending commit-to-FIB absolute time in TLV in LSP
(Router NTP can give 500us precision easily). But maybe that wouldn't
be deterministic enough. In oFIB I fear that FIB delay in devices I'd
actually want to use in practical scenarios are less than my
linkdelays, so signalling would just reduce convergence time.

-- 
  ++ytti