Subject: Re: [Isis-wg] Hello Intervals

From: Radia Perlman - Boston Center for Networking <[email-masked]>
Date: Mon, 11 Sep 2000 21:17:01 -0400 (EDT)

>>	From: Danny McPherson <[email-masked]>

>>	Several service provider networks I'm familiar with actually increase 
the 
>>	multiplier to 4 or 5 and lower the interval to 1-2s. 

What is the value in increasing the multiplier? I understand why you'd
want to set the hello interval to be small in order to detect failure
quickly. The only reason I could imagine for setting the multiplier
higher is if the link is very flaky and it's likely you'll miss
several hellos in a row. Are the networks you refer to
using very fast and very flaky links?
Or are the routers likely to lose a lot of packets without looking at
them first, so that most hellos do get lost?

Just curious...

Radia

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From: Robert Raszuk <[email-masked]>
Date: Mon, 11 Sep 2000 20:55:16 -0700

Radia,

One of the reasons I know of for incresing the multiplier would be to
avoid unnecessary adj. flaps when you have bursts of traffic - hence
temporary congestions - and your hardware is not capable of separating
discarded protocol packets from data packets on an ingress line card. (I
know a few boxes which have such a characteristic :).

R.

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From: Tony Li <[email-masked]>
Date: Mon, 11 Sep 2000 22:53:52 -0700 (PDT)

| One of the reasons I know of for incresing the multiplier would be to
 | avoid unnecessary adj. flaps when you have bursts of traffic - hence
 | temporary congestions - and your hardware is not capable of separating
 | discarded protocol packets from data packets on an ingress line card. (I
 | know a few boxes which have such a characteristic :).

And before this provokes a discussion, I think most folks would agree that
that's not a particularly robust implementation.

Tony