RE: Advertisement Interval Vs Timeout

Danny,

Actually I agree with you 100%, and I made similar
arguments earlier. Theoretically, this result doesn't
make sense and I suspect it really means something
else is going on that we don't yet understand.

Nevertheless, since *I* was not (and am still not)
in a position to get any hands on experience, I felt
I should defer to the people that were actually seeing
the issues first hand, even when the protocol itself
was being complicated by the issue, as was the case
then.

Happily, as things stand now (with the Minimum
Advert Int), it's no longer a protocol issue at all,
and we can leave it to administrators actually in the
field with real operational environments to adjust
this value if they find they need to. The cost to
the protocol itself is now essentially zero: "less
than or equal to" vs. just "equal to", and even that's
in the implementation, not the protocol description.

(Well, except I guess it makes sense to add an
"actual advert interval" to the MIB, although I
hate to say it.)

-don

> -----Original Message-----
> From: Danny J. Mitzel [mailto:[email protected]]
> Sent: Tuesday, April 17, 2007 2:00 PM
> To: [email protected]
> Subject: RE: [VRRP] Advertisement Interval Vs Timeout
> 
> 
> I'll admit right up front that I haven't been
> following the subsecond timers draft, feel free to
> ignore this question if it's already been discussed.
> 
> 
> --- Don Provan <[email protected]> wrote:
> > If the master were allowed to send at faster rates,
> > more than three advertisements could be sent per
> > timeout interval, which is what people experimenting
> > with faster timeouts tell us they found was 
> > necessary for stability in that environment.
> 
> I'm not understanding why people experimenting with
> faster timeouts are claiming more Advertisements
> are required to insure VRRP stability?  Stability of
> the protocol as currently written is not dependent on
> the timeout interval it's dependent on the packet loss
> rate (link Bit Error Rate (BER) and/or switch or
> router packet drops).  Are the fast timeout
> experimenters emulating higher BER or non-linerate
> capable switches with high packet drop rates?
> 
> I agree that the ability to send Advertisements at a
> higher rate can make VRRP more robust in LANs with
> extremely high BER or congested switches.  I'm just
> trying to understand if there's some claim that this
> is required just because the timeout is scaled down?
> 
> 
> danny
> 
> 
> 
> 
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