SUMMARY: le0: No carrier - error

From: ken lewis (
Date: Wed Jul 22 1992 - 21:57:09 CDT

Thanks to all for the quick response. (THEGR81) (Anthony Veale')
daniel@CANR.Hydro.Qc.CA (Daniel Hurtubise) (Gurvinder Singh Ahluwalia) (Lance Eric Greenwade)
jsin@JANET.UCLA.EDU (John Sin)
era@niwot.scd.ucar.EDU (Ed Arnold) (HAO Computer System Managment Group)
deltam!tigger!jt@uunet.UU.NET (jim wills)
Robert Allan Zeh <> (Michael Baumann)
guyj (Guy Jones) (John M. Crowell)
zeke@mpl.UCSD.EDU (Rob Scott)
Kayvan Sylvan <kayvan@satyr.Sylvan.COM>

My original question was:

        I have been receiving the following error message several times a day
        for many weeks.
        le0: No carrier - transceiver cable problem?
        This error is not hardware related.
        The cable and transceiver have been swapped.
        the cable has not been coming loose at either end.
        What are the other possibilities that could generate this message
        and are they something to worry about?
As many pointed out, it may still be a hardware error even though the transceiver
and cable are ok. Which is really what I meant to say (nothing like a poorly worded
question to simulate response). I also should have added that this is a 10BT network.

The most succinct description of the error message was
        The le0 chip has lost input to its carrier detect pin
        while trying to transmit a packet, causing the packet
        to be dropped. Possible causes include an open circuit
        somewhere in the network and noise on the carrier
        detect line from the transceiver.

I have not tested all the responses but all are valid places to check if you have
similar problems.

1) cabling/termination is the most common answer.

   a) thicknet check your tap
   b) thinnet check your connections and tees.
   c) 10bt test cable again
   d) bad terminator or grounding
   e) in all cases look for other potential electro-magnetic
      interferance, like flourescent lights.

2) other hardware problems include
   a) mother bd going bad (le0 chip)
   b) concentrator going bad
   c) bad transceiver elsewhere on net

3) the network is heavily loaded with traffic.

4) the thin-net coax connected to the transceiver had a floating ground
    where it was connected to a multiport repeater on the floor below.
    So check continuity, grounding, and termination on the LAN.


1) get a good cable analyser for your type of cabling.

2) Connect another machine to the same wall socket and/or
   move this machine to a different wall socket

3) Put two terminators directly onto the Sun transceiver to establish
   that neither the transcievcer or the terminators are at fault.
   Then add each length of ethernet cable, one at a time until you find
   the culprit.

4) use 10BASET technology not Ungermann-Bass Net/One Twisted Pair equipment

5) disable SQE/enable SQE

6) use ifconfig -a to check network #'s for le0 lo0

      _ |_| Kenneth R. Lewis,
   _ |_| Applied Software
  |_| 1908 Cliff Valley Way
   _ _ _ Atlanta, Georgia 30329
  |_||_||_| Voice: (404) 633-8660
   _ _ _ Fax: (404) 633-0154
  |_||_||_| Internet:

Be excellent to everyone.

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