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From: bmar@cac.washington.edu (Bill Mar)
Newsgroups: comp.dcom.sys.cisco
Subject: Re: Appliques can fail .....
Message-ID: <32744@boulder.Colorado.EDU>
Date: 28 Feb 91 02:54:21 GMT
Sender: daemon@boulder.Colorado.EDU
Lines: 15

We had similar symptoms while evaluating the new Codex 3500 56k DSUs on
a production circuit between two cisco routers.  Problem was resolved by
replacing the V.35 applique with a later vrs 6.  Apparently vrs 4 and 5
incorrectly inverted some of the data and/or clock lines, which was
corrected in vrs 6.  The symptoms do not neccessarily show up
immediately, because four pairs of different vendor/model DSUs tested
fine on this circuit.  When the 3500s were tried, they BERT'd the
circuit ok, PING'd locally ok, but could not PING across the link. 
Codex concludes the 3500 is designed to enforce industry standard data
and clock phase relation, while the older DSUs allowed out of spec phase
and the frequently less than desirable results. 

Bill Mar
Univ of Wash
Seattle, WA