Subject: interoperability with draft12 LAC

From: Venkatesan Pradeep <[email-masked]>
Date: Mon, 28 Feb 2000 18:27:31 -0800 (PST)

I am implementing an LNS and I want to be able to deal with both
draft12 and RFC compliant LACs. I want to have sequence numbers on
all payload packets, by default. Since both RFC and draft12 say that
payload packet sequencing can be dynamically enabled/disabled by the
LNS, I thought it would be a simple matter of having the LNS start
sending out packets with sequence numbers after the session is
established.

However, I found that the LAC (most likely a draft12 implementation)
that I am using does not send sequence numbers unless I send a
RWS AVP in the ICRP. Is the LAC behaving correctly w.r.t draft12?

According to draft12, unless either peer sends a RWS AVP, sequence
numbers are absent for the session but it also says that if the LAC
has not sent the Sequencing Required AVP, the LNS is free to
dyanmically enable or disable sequencing. Perhaps the LAC I am using is
interpreting this to mean that since RWS AVP has not been sent by
either peer there is no sequencing involved and thus the LNS cannot
enable it - it can only disable sequencing if already enabled and
re-enable it.

If the LAC is behaving correctly, how do I deal with this situation?.
I thought of sending an ICRP with the RWS AVP with RW=0 but that
would make me behave like a draft12 LNS.

Thanks,

Pradeep.

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From: "W. Mark Townsley" <[email-masked]>
Date: Tue, 29 Feb 2000 02:14:42 -0500

> sending out packets with sequence numbers after the session is

Should be.

> RWS AVP in the ICRP. Is the LAC behaving correctly w.r.t draft12?

It is actually operating pre-draft 12. If it were operating at draft-12,
then it should handle the dynamic sequencing.

> dyanmically enable or disable sequencing. 

That is correct. It had both.

> Perhaps the LAC I am using is

No, you had it right the first time.

> would make me behave like a draft12 LNS.

Depends on how important it is for you to work with this LAC, and/or how
willing they are to change. You are in the "right" given the current
RFC, as well as draft 12. But, if you want to work with them now and
have no other course, it is fairly safe to send the RWS AVP=0 as most
implementations are aware of its existance. If you do this, I would
suggest being able to configure this mode on/off in the hopes of not
needing it one day.

- Mark