Path: utzoo!mnetor!uunet!husc6!think!ames!ptsfa!varian!kinetics!tim
From: tim@kinetics.UUCP (Tim McCreery)
Newsgroups: comp.protocols.appletalk
Subject: Re: Kinetics Fastpath hardware bug
Message-ID: <196@kinetics.UUCP>
Date: 12 Dec 87 23:40:59 GMT
References: <8712090036.AA02061@umd5.UMD.EDU>
Reply-To: tim@kinetics.UUCP (Tim McCreery)
Organization: Kinetics, Inc., Walnut Creek, CA.
Lines: 33

I have not been keeping up with reading this newsgroup lately,
but the recent item by Dan Magorian concerning FastPath definitely
got my attention. Mostly, I want to clear up a few points with some facts.

The "hardware bug", i. e. "misplaced capacator (sic)" is not quite
correct. In different network environments, tranceivers, tranceiver
cables, etc. inject different levels of noise into the gateway.
There is a crystal oscillator circuit to the SIA (usually the AMD 7992)
and the sensitivity to noise of the TCLK input to that SIA is also
quite variable. Therefore, different units experience noise problems
to lesser (i. e. not at all) or greater extent. Reduced noise sensitivity
can be obtained by moving a capacitor closer to the serial interface chip,
thereby reducing some of the common ground path near it. All current and
future units from Kinetics are reducing noise sensitivity in this fashion.

We recommend this capacitor movement change to all sites which are
experiencing an intermittent failure problem which shows up as the
boxes appear to hang (no RTMP packets are being sent), but then fully
recover after a power cycle. I should note that most problems reported
to us are not like this, but are due to configuration inconsistencies
and this "fix" will not solve those problems.

With respect to Microsoft, the implication in Dan's article is that ALL
the units were failing several times per day. This is false. Because of
the size of the Microsoft installation and their excellent network
administration, they became an ideal site for diagnosing the problem
as being unit and environment specific. We are grateful for their patience
and assistance in helping us first document and then find this problem.

We are in the process of writing a technical note concerning this problem
and the fix and will be mailing it to all of our customers within the next
week or so.
tim