Subject: RE: [Isis-wg] Three-way Handshake question

From: Les Ginsberg <[email-masked]>
Date: Tue, 15 May 2001 17:02:22 -0700

All very true.

Which is why it would be "nice" if the current 3way draft were updated to
indicate that the TLV has an acceptable form that includes only the
adjacency state and that the len could be "1-17" rather than "5-17".

Given that the old form of handshake is still in widespread use this is more
than a historical issue.

   Les

> 
> 
> > 
> > Hi,
> > 
> > I have a question related to the Three-Way handshake operation.
> > 
> > In the "Point-to-Point Adjacency State" TLV definition of
> > draft-ietf-isis-3way-03, length is defined to be between 5 
> to 17 octets.
> > However, I have noticed that some implementations have only 
> the "Adjacency
> > State" included in this TLV. i.e. "Extended Local Circuit ID" is not
> > included.
> > 
> > What is the expected behavior on receipt of such a IIH PDU?
> 
>   Be strict in what you send, be liberal in what you accept.
> 
>   The first version of the 3-way handshake used to have only 
> the "Adjacency
>  State" included. Many years after this had been implemented, 
> the need for
>  more information in the TLV arose. There are still a zillion 
> routers out
>  there that only send and understand the first byte of the 
> TLV. The dominant
>  implementation of those days luckily will ignore any extra 
> bytes in the TLV.
> 
>   So IMHO if you know about this, you should build your 
> implementation in
>  such a way that it will be able to interoperate with these 
> older boxes.
>  Your customers will appreciate it.
> 
>     hope this helps,
> 
>                     henk.
> 
> 
> > Thanks,
> > Ravi
> > _______________________________________________
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> > 
> 
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