12-29-2009 08:13 AM - edited 03-06-2019 09:06 AM
I am getting some complaints from users on a telnet app that is breaking. It seems like the session freezes. They get an error. I researched the error and I found that it was a connectivity problem.
So I looked at the interfaces of the switch where these people site. here is an an example:
FastEthernet2/12 is up, line protocol is up (connected)
!
!
5 minute output rate 0 bits/sec, 0 packets/sec
0 packets input, 0 bytes, 0 no buffer
Received 0 broadcasts (0 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 input packets with dribble condition detected
418 packets output, 47790 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out
Most of the time this is how they look. All the ports look good.
Ocassionnally I see an increment on 1 lost carrier. This happens to all ports on the switch. And then it goes away. I have not been able to correlate the lost carrier increment and the lost telnet session. What does it mean to have a lost carrier? I guess my question is could a lost carrier break a tcp session?
Thanks,
Pete
12-29-2009 08:30 AM
Check for a bad cable. This is usually a physical issue.
Mike
12-29-2009 08:37 AM
Thanks Burleyman for the information.
The odd thing about the 1 Lost Carrier increment is that it is switch wide. In other words, when it happens, it happens to all the ports that are connected at the time except the fiber uplinks. The fiber links do not have any lost carrier increment. It only happens to the copper ports on all blades.
What does this say I cannot be sure. An electrical problem perhaps?
Still I wonder if a lost carrier would break a tcp session?
12-29-2009 09:01 AM
I would check the other end (server connection) to see if the issue is there and not on the users switch. See this documnet for troubleshooting interface errors.
http://www.cisco.com/en/US/products/hw/switches/ps700/products_tech_note09186a008015bfd6.shtml
Hope this helps,
Mike
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide