Subject: [Isis-wg] More comments on draft-ietf-isis-restart-01.txt

From: "Kent Wong" <[email-masked]>
Date: Thu, 20 Jun 2002 01:37:25 +0000

Hi,

Sorry if you got this e-mail more than once. I have trouble
sending the e-mail to the ISIS WG mailing list.

Some more comments on the draft:

1. On page 8, the draft states that SPF should not be run
when T3 is running. But on page 9, it says that if T3 expires
before T2, the level which have not completed their first SPF
run should generate LSP with OL bit set. But no level will
run their SPF before T3 expires anyway. Should this be
interpreted as "level of which T2 is still running should
generate their LSP with OL bit set"?

2. Along the same line of thought, I still don't understand
why we need two different timers T2 and T3. When T2 finishes,
T3 would be cancelled anyway. The only case T3 is supposed
to be useful is if it expires before T2, the restarting router
is supposed to generate own LSP with OL bit set. However,
this assumes that the restarting router has acquired its own
pre-start LSP before T3 expires. If not, what should the seq
number it use to generate the zeroth LSP with OL bit set? If the
seq num it uses in zeroth LSP is smaller than the nbr's DB copy,
the zeroth LSP will be ignored by helper nbr anyway.

So why not just combine T2 and T3 into a single timer per level and
set the timer to be the min. remaining holding time of its nbr.
If the timer expires before the DB re-sync finishes, then graceful
restart fails and everything reverts back to normal. Isn't this much
much simpler and effective?

Thanks.

Kent Wong

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