Late collision error on int fa0/0

[M Talha]

Pls someone help me in this regard, i am getting this error everything else is working fine.

i am using cisco 2801. Any help would be greatly appreciated. Thanks

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*Aug 29 06:25:15.179: %GT96K_FE-5-LATECOLL: Late Collision on int  FastEthernet0

/0

*Aug 29 06:25:16.743: %GT96K_FE-5-LATECOLL: Late Collision on int  FastEthernet0

/0

*Aug 29 06:25:16.743: %GT96K_FE-5-LATECOLL: Late Collision on int  FastEthernet0

/0

*Aug 29 06:25:17.179: %LINK-3-UPDOWN: Interface FastEthernet0/0, changed state t

o up

*Aug 29 06:25:17.455: %GT96K_FE-5-LATECOLL: Late Collision on int  FastEthernet0

/0

*Aug 29 06:25:17.775: %GT96K_FE-5-LATECOLL: Late Collision on int  FastEthernet0

/0

*Aug 29 06:25:19.067: %GT96K_FE-5-LATECOLL: Late Collision on int  FastEthernet0

/0

*Aug 29 06:25:19.455: %LINK-3-UPDOWN: Interface FastEthernet0/0, changed state t

o up

*Aug 29 06:25:23.471: %GT96K_FE-5-LATECOLL: Late Collision on int  FastEthernet0

/0

*Aug 29 06:25:23.591: %GT96K_FE-5-LATECOLL: Late Collision on int  FastEthernet0

/0

*Aug 29 06:25:23.959: %GT96K_FE-5-LATECOLL: Late Collision on int  FastEthernet0

/0

*Aug 29 06:25:24.123: %GT96K_FE-5-LATECOLL: Late Collision on int  FastEthernet0

/0

*Aug 29 06:25:24.291: %GT96K_FE-5-LATECOLL: Late Collision on int  FastEthernet0

/0

*Aug 29 06:25:24.943: %GT96K_FE-5-LATECOLL: Late Collision on int  FastEthernet0

/0

*Aug 29 06:25:25.471: %LINK-3-UPDOWN: Interface FastEthernet0/0, changed state t

o up

*Aug 29 06:25:25.599: %GT96K_FE-5-LATECOLL: Late Collision on int  FastEthernet0

/0

[Kevin Dorrell · Accepted solution]

My guess is that you have a duplex mismatch.  The sitchport thinks it is half-duplex, and the thing connected to it is full duplex.  Can you post a "show int F0/0", and let us kow what is connected on the port?

Kevin Dorrell

Luxembourg

[M Talha]

Here is the output of F0/0 interface

Router#show int F0/0

FastEthernet0/0 is up, line protocol is up

  Hardware is Gt96k FE, address is 001f.6ccf.1f28 (bia 001f.6ccf.1f28)

  Internet address is 58.27.246.10/30

  MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,

     reliability 255/255, txload 1/255, rxload 2/255

  Encapsulation ARPA, loopback not set

  Keepalive set (10 sec)

  Half-duplex, 100Mb/s, 100BaseTX/FX

  ARP type: ARPA, ARP Timeout 04:00:00

  Last input 00:00:01, output 00:00:00, output hang never

  Last clearing of "show interface" counters never

  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

  Queueing strategy: fifo

  Output queue: 0/40 (size/max)

  5 minute input rate 878000 bits/sec, 130 packets/sec

  5 minute output rate 634000 bits/sec, 132 packets/sec

     243048 packets input, 162012637 bytes

     Received 43 broadcasts, 0 runts, 0 giants, 0 throttles

     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

     0 watchdog

     0 input packets with dribble condition detected

     289275 packets output, 237012333 bytes, 0 underruns

     1970 output errors, 4852 collisions, 1861 interface resets

     0 unknown protocol drops

     0 babbles, 1973 late collision, 0 deferred

     0 lost carrier, 0 no carrier

     0 output buffer failures, 0 output buffers swapped out

[Kevin Dorrell]

My peferred way of dealing with duplex on a 100 Mbps Ethernet is to rely on the auto at both ends.  A common mistake is to have auto on the switch, but to hard-configure full-duplex on the attached host.  This will result in the sort of situation you have here.  The hard-configured full-duplex will disable the negotiation, so the switch will therefore revert to half-duplex, resulting in the mismatch.

Kevin Dorrell

Luxembourg

[Peter Paluch]

Kevin,

Good catch! I absolutely second your choice. In fact, I avoid setting the speed and duplex manually unless necessary for (usually) obscure reasons. The autonegotiation may have been unreliable in its early beginnings but now it works fine. One can do much more harm by circumventing it than by relying on it.

Best regards,

Peter