SUMMARY: Twisted Pair Ethernet

From: Keith McNeill (eplrx7!
Date: Mon Jul 15 1991 - 16:11:24 CDT

After a little summary.

My original message:

> We just switched some systems to unshielded twisted pair (UTP) ethernet. On all
> the Sun's on the UTP we see a lot of:
> le0: No carrier - transceiver cable problem?
> Both of our UTP hubs have the same problem.
> Are other people seeing this problem with twisted pair? Is there anything
> that can be done about this or is this just the nature of the beast.
> We are using Ungermann-Bass Net/One Twisted Pair equipment.

The very day I sent out the note my intrepid networking people fixed the
problem....Murphy strikes again.

Ungermann-Bass has 2 twisted pair ethernet cards. The old version
implements UB's pre-10BASET standard version of UTP (model # ECM300). The
new version implements the 10BASET standard (model # ECM310). We were using
the old version. The networking people had a beta 10BASET version that they
swapped in on one of our hubs. Since then there have been no

        le0: No carrier - transceiver cable problem?

messages on that hub.

Most people replied that they were having no problems at all (one person has
1000's of nodes on UTP) using several different UTP vendors. Among the

        check the connections
        check the transceiver
        make sure the cabling is not too close to electrical cabling or
                fluorescent lights
        disable SQE
        enable SQE
        YELL, SCREAM, THREATEN the vendor to fix the problem
        use shielded twisted pair
        don't fear actually works

I'd add to the list:

        make sure you are using 10BASET technology not UB's UTP

Thanks to:

cogsci.UCSD.EDU!wallen (Mark R. Wallen)!osm (Owen Scott Medd)!matt (Matt Goheen)!tim (Kam Tim Chan)
fid.Morgan.COM!dpk (Doug Kingston)!scott (Scott Hazen Mueller)!casper (Casper H.S. Dik)
Richard Niziak <uunet!!ontologic!gremlin!rickn>
uunet!CS.YALE.EDU!long-morrow!shj (Steve Jay)!pomeranz (Hal Pomeranz)
ddull@Rational.COM!oran (Oran Davis)
Rex Mammel <uunet!!rexm>


    Keith McNeill | Du Pont Company
    eplrx7! | Engineering Physics Laboratory
    (302) 695-9353/7395 | P.O. Box 80357
                                  | Wilmington, Delaware 19880-0357

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