Collision Errors on interfaces

[jennyjohn]

I am getting collision errors on couple of interfaces on the my WS-C4506-E switch. The interfaces are all RJ45 interfaces.

Code: Select all

DIST_SW# sh int gi 3/22
GigabitEthernet3/22 is up, line protocol is up (connected)
  Hardware is Gigabit Ethernet Port, address is 000e.d742.a355 (bia 000e.d742.a355)
  Description: *** Connected to User ***
  MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Half-duplex, 100Mb/s, link type is auto, media type is 10/100/1000-TX
  input flow-control is on, output flow-control is on
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 18w5d, output never, output hang never
  Last clearing of "show interface" counters 3w4d
  Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 3000 bits/sec, 6 packets/sec
     846934 packets input, 161967727 bytes, 0 no buffer
     Received 1518 broadcasts (0 multicasts)
     1154661 runts, 0 giants, 0 throttles
     1154661 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 input packets with dribble condition detected
     22272881 packets output, 4849858040 bytes, 0 underruns
     0 output errors, 885620 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

DIST_SW#sh interfaces gi 3/22 counters errors

Port       CrcAlign-Err Dropped-Bad-Pkts Collisions   Symbol-Err
Gi3/22                0                0                 36509            0

Port          Undersize  Oversize  Fragments      Jabbers
Gi3/22                0           0          46886              0

Port         Single-Col Multi-Col   Late-Col   Excess-Col
Gi3/22        28164       8345            0               0

Port       Deferred-Col False-Car  Carri-Sen Sequence-Err
Gi3/22          226             0              0              0


I am getting Fragment errors, Single-Col, Multi-Col and Deferred-Col errors, What does it all mean?
If I change the cable will it get fixed?


Thanks in advance

[leolaohoo]

Half-duplex, 100Mb/s, link type is auto, media type is 10/100/1000-TX

It's caused by "half duplex". Make sure the client is set to auto-negotiate.

[jennyjohn]

Thanks all you guys,

I found out that all the connected devices were Xerox machines and they were all set to Half duplex.
I have set it to auto and now there are no collisions to be seen on the interfaces.

[ganeshh_iyer]

As pointed by leo check out the peer end duplex and speed setting,it should be on auto state or try hard code at both the ends.


Hope to Help !!
Ganesh.H

[Richard Burts]

Both Leo and Ganesh focus on the fact that the interface is operating in half duplex mode and assume that perhaps this represents a problem in negotiation with the peer, reflecting the common assumption that most switch ports would operate in full duplex mode. I wonder if both the switch and the peer are operating in half duplex mode and therefore is not really a problem. If the peer were full duplex and the switch was half duplex I would expect to see late collisions and none are reported.

Collisions are expected when Ethernet is operating in half duplex mode. And looking at your numbers I am not sure that the collisions are excessive. But if the collisions are alarming you then you should try to get both the switch and the connected device to operate in full duplex mode. In doing this it is important that both devices use the same approach. Either both devices should auto negotiate both speed and duplex or both devices should set both speed and duplex.


HTH
Rick