[nsp] LCP id mismatches

From: Tim Franklin (tim@colt.net)
Date: Fri Aug 04 2000 - 07:11:22 EDT


Has anyone seen before a problem between a Cisco 800 and AS5300 where on an
ISDN dial-up session, the 800 issues LCP CONFACKs with what appear to be
bogus ids? The problem seems to be tied to which end starts talking first.
The case where things work normally runs like:

AS5300 800
               <-- CONFREQ,id=93
CONFACK,id=93 -->
CONFREQ,id=7 -->
               <-- CONFACK,id=7

When it doesn't work, the sequence is:

AS5300 800
CONFREQ,id=8 -->
               <-- CONFREQ,id=94
CONFACK,id=94 -->
               <-- CONFACK,id=94

ie instead of ACKing the REQ it receives, the 800 appears to being trying to
ACK the ACK it received for its own REQ.

At this point the AS5300 reports 'LCP: ID 94 didn't match 8, discarding
packet' and starts the whole negotiation again, until it times out and hangs
up. Re-dialling usually gets the first timing sequence which works,
although occasionally there's a run of failures.

AS5300 is 12.0(4)XJ3, 800 has been tried with 12.0(5)T and 12.0(7)T.

Any pointers gratefully received,
Tim.

--
Tim Franklin           Email: tim@colt.net
Project Engineer       Phone: +44 20 7390 7848
COLT Internet          Fax: +44 20 7863 5876



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