Subject: [pim] Transmission of Holdtime info

From: [email-masked]
Date: Wed, 11 Sep 2002 23:02:46 -0400 (EDT)

Hello,

Whenever Hello_Period is an odd number, Holdtime in the Hello Message will
not be a whole number.  However, according to section 4.10.2:

"Holdtime is the amount of time a receiver must keep the neighbor
reachable, in seconds."

In this situation, is Holdtime truncated or rounded up?  What is compliant
behavior?

Thanks,
-Ben

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From: Pavlin Radoslavov <[email-masked]>
Date: Thu, 12 Sep 2002 00:05:40 -0700

> In this situation, is Holdtime truncated or rounded up?  What is compliant

It shoudn't really matter. Either truncation or rounding up would be
compliant.
If you configure two routers with Hello_Period of, say, 31 seconds,
the "worst" could happen is one of them will be sending Hello
messages with Hello_Holdtime of 108, and the other one with 109
secs.
The Hello_Holdtime doesn't have to be same for neighbors, so those
routers would work fine without any interoperability issues.

Regards,
Pavlin

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From: John Zwiebel <[email-masked]>
Date: Thu, 12 Sep 2002 10:47:31 -0700

Round up if you have any doubts.  You don't want a hold time of zero
 seconds.

OTOH: experience has shown that changing this isn't all that beneficial
 since it (at least in theory) should then also change the hold time in
 all other PIM messages, which leads to problems in getting all the
 routers on the network configured with the same times.

I'm not saying that it can't be done, but it isn't as obvious as one
 might first believe.