Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!noao!asuvax!mcdphx!mcdphx.UUCP!dtk
From: dtk@mcdphx.UUCP (Dave)
Newsgroups: comp.dcom.lans
Subject: Re: Cabletron Twisted Pair Ethernet
Keywords: twisted pair ethernet
Message-ID: <10610@mcdphx.phx.mcd.mot.com>
Date: 28 Mar 89 19:17:45 GMT
References: <1297@cunixc.cc.columbia.edu>
Sender: listen@mcdphx.phx.mcd.mot.com
Reply-To: dtk@mcdphx.UUCP (Dave)
Distribution: usa
Organization: Motorola Microcomputer Division, Tempe, Az.
Lines: 53

In article <1297@cunixc.cc.columbia.edu> chen@cunixc.cc.columbia.edu (Bill Chen) writes:
>I've seen notes bounce around about Synoptics Lattisnet, but has
>anyone had experiences (good or bad) with Cabletron's twisted pair
>ethernet product (MMAC-3)?

At mcdphx we have recently installed our new facility with Cabletron
MMAC-3 twisted pair ethernet along with ATT wiring and pds. Our
network consists of 5 MMAC-8's and 3 MMAC-3's with the Cabletron
FOT fiber transceivers between buildings.  We ordered the "dumb"
repeater modules, but were sent and not charged for the "intelligent"
repeater modules (IRM). My experience has been good with Cabletron support
personnel.

We had one MMAC-3 DOA, due to a power supply problem, and have had
another power supply module die since installation. We have been
online since 1/89.

The intelligent repeater module is of limited use since no one seems
to know what constitutes an error to increment on the status screen.
The error could be a runt/oversize/late collision or ???.  As such, it
may flag a problem, but really points you to use other tools.  The
limits and other "features" in the IRM are disabled, and I feel of
little use.  During the demo of the MMAC, the entire network shutdown
because the sales person had enabled the limits with very small
values. As soon as the values were exceeded, the ports were disabled.
Since we were not in the pds room, we tried all sorts of things before
figuring out that the ports were disabled. We use a dumb terminal
hooked to the IRM and not the PC based software.

We have installed ~ 225 tpt2 transceivers with 5 DOA.  I thought the
leds would be of limited use, but they have been very useful.

I am not terribly overjoyed at the number of errors reported by the IRM
or by the number of errors detected by our hosts.  The number is well
within the 802 spec, but is a jump from our previous configuration of
"mellow yellow", RG8.

I guess my recommendation would be summed up in that we are buying a
whole new set of Cabletron MMAC's for the old building.

The biggest problem getting the network up was wiring, bad rj45
connections, and twisted pairs to/from the pds.  It also is a 
challenge to keep an accurate picture of the pds with all the phone,
 rs232, and TP enet running through.
We used the patch cords for maximum flexibility and
I believe this to be a mistake.  Our pds is very difficult to work on
since all the patch cords form a large vertical pile.

We use it, we abuse it, and it works for us.

Dave Knappenberger     dtk@mcdphx.UUCP	(602) 438-3741
These are my opinions and not necessarily those of
Motorola Micro Computer Division