Subject: RE: [Isis-wg] Operation of P-toP links

From: Neal Castagnoli <[email-masked]>
Date: Wed, 2 May 2001 14:50:23 -0700

> any decent implementation does only flush its own LSPs these 
> days. Flushing
> other people LSPs has proven to be a bad idea.

Right.  In NLSP we eliminated the "bad checksum purge" when receiving
corrupted LSPs, because a corrupting link (or misbehaving router on the
other end of the link) could bring down a network.  We discarded the bad
ones, and alerted the administrator.

The other instance of a network wide purge is receipt of an LSP that has the
same "newness" (same sequence number, same lspid, both non-zero lifetime),
but different checksums.  In this case, we included checksum as a part of
the "newer" calculation.  LSPs with higher checksums were "newer."  This
prevented routers from purging others LSPs, and in the case of two routers
battling over a system ID, it allowed the LSPs to flow back and forth
between the battling routers (both routers complain).

Is this being done with ISIS implementations?  If so, it seems all routers
need to have the same algorithm (what is it?).  If not, what is being done
to prevent the purge?

>> <way to recover from corrupt LSPs in the database deleted>
> even simpler solutions to the problem exist given some 
> cooperation from your
> neighbor
> 

Do you know what the simpler solutions are?  Care to describe them?

(which begs the question of whether it is even right to try to recover!).

>             -- tony

  --Neal
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From: Tony Przygienda <[email-masked]>
Date: Wed, 02 May 2001 15:32:11 -0700

> (which begs the question of whether it is even right to try to recover!).

think sending SNPs when the spec doesn't call for it. Most implementation
will do the right thing then.

Whether it is right to recover depends on many things, one of them your
marketing departement and overall architecture of the box ;-)

    'nuff said

    -=-= tony