Subject: [Isis-wg] do different p2p DataLinkBlockSizes work with IS-IS

From: Norbert van Bolhuis <[email-masked]>
Date: Tue, 23 Mar 2004 12:31:53 +0100

Do different p2p DataLinkBlockSizes actually work with
IS-IS (RFC 1195 and/or ISO-10589 v2001 *without* the three-way
handshake p2p extension) ?

What should happen is that Node-A with DLB A and Node-B with DLB B,
(given that DLB A != DLB B) should not get an IS-IS level 1 p2p
adjacency, but I think they do.

The problem is that, suppose DLB A > DLB B, Node A (which correctly
receives the first (padded) p2p IIH from Node B) will send unpadded
p2p IIHs after sending the first one (shich should be padded).
Although Node B couldn't receive the first p2p IIH, it can receive
all subsequent ones since they are not padded anymore.
As a consequence both Nodes establish a p2p adjacency to eachother.

Is the above really true, and is this a problem in the IS-IS standard
or do I miss something.

Thanks in advance for any response/comment.

Norbert van Bolhuis.

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From: Les Ginsberg <[email-masked]>
Date: Wed, 24 Mar 2004 15:41:59 -0800

Norbert -

This question pops up every so often. Thanx to Jeff Parker (and friends) we 
now have a readily available answer.
Please see RFC 3719 Section 6.
If you still have questions after reading that, let us know.

     Les