Re: [RRG] Re: map change due to a path failure?

["William Herrin" <bill@herrin.us>]

On Mon, Mar 24, 2008 at 10:14 PM, Stephen Sprunk <stephen@sprunk.org> wrote:
> Thus spake "William Herrin" <bill@herrin.us>
>  > 2a. What's the maximum acceptable time in which one EID may be
>  > inaccessible to another during change propagation due to a path
>  > failure?
>
>  A second or two at most, ideally, because folks are going to try to run VoIP
>  over this system.  The good news is that it's not "zero" or "50ms" like it
>  would have been a decade ago, as cell phones have conditioned people to
>  expect occasional audio loss they wouldn't have accepted when accustomed to
>  the general high reliability of the wireline PSTN.

Gak; hit the send button early. Okay, lets try that again.

Two seconds is extremely ambitious for any architecture. BGP takes
anywhere from 30 to 120 seconds under normal conditions. I'm not sure
its possible to reliably detect that a path has failed in two seconds,
let alone propagate state change knowledge.

Bear in mind, this question is a two parter. There's also:

2b. What's the maximum acceptable time in which one EID may be
inaccessible to another because of a planned change?

Two seconds might well be a reasonable answer to 2b and 0 seconds may
turn out to be possible.

Regards,
Bill Herrin


-- 
William D. Herrin ................ herrin@dirtside.com  bill@herrin.us
3005 Crane Dr. ...................... Web: <http://bill.herrin.us/>
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