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I haven't found a really clear definition about what a 'carrier error' is within the context of the ifconfig output for a interface. I have been searching on Google and there really isn't a great definition, or list of issues that cause this.

I am assuming from the context, that this means something about the Ethernet signal is bad. I suspect something about the interconnecting cable, or the network interface/port is causing this problem?

I hardly ever see this counter changing, but a client contacted me this morning and mentioned network issues. The carrier counter is increasing by about 200 each second. They had recently made some modifications to the equipment connecting to the Linux box I manage. I would like to be able to give them some more specific details about what may be causing the problem, other then saying, something you changed is broke.

eth0      Link encap:Ethernet  HWaddr 00:1b:21:f3:ea:ae  
          inet addr:172.16.0.9  Bcast:172.16.255.255  Mask:255.255.0.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:13386121 errors:0 dropped:0 overruns:0 frame:0
          TX packets:21255715 errors:1701 dropped:0 overruns:0 carrier:1031707
          collisions:1313642 txqueuelen:1000 
          RX bytes:2467874046 (2.2 GiB)  TX bytes:3820141165 (3.5 GiB)

So what is it a 'carrier error', and what are the typical problems that cause it.

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Most of the time I've seen this is wh.@((%!($*@****CARRIER LOST –  EEAA Oct 28 '11 at 19:44
    
Upvoted because it was your 42nd question. –  Wesley Dec 17 '11 at 8:14
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1 Answer

up vote 5 down vote accepted

Carrier errors occur when there is a problem with the modulation of your signal.

This could indicate either a duplex mismatch, or a problem with the physical cable/connector.

Restarting autonegotiation and checking the ethernet connector are some things you could try to fix the problem.

Look here for some instructions on how to restart autonegotiation.

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I would suspect a duplex mismatch based on the number of collisions being reported. –  joeqwerty Oct 28 '11 at 19:31
    
I must be blind, I didn't even notice the collisions. Yes, a duplex issue seems likely. –  Zoredache Oct 28 '11 at 20:00
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