Very high collision

Answered Question
Apr 15th, 2010

Hi everyone,

One of the switches in my network, there is more than one interface has a lot of collisions. May I know it could be effect the switch or is it a normal situation? I also attach one of the interface’s information. I really appreciate any advice.

FastEthernet0/23 is up, line protocol is up (connected)

  Hardware is Fast Ethernet, address is 0018.1904.8217 (bia 0018.1904.8217)

  Description: "CCTV"

  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, media type is 100BaseFX

  input flow-control is off, output flow-control is unsupported

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

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

  Last clearing of "show interface" counters 12w4d

  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 148000 bits/sec, 29 packets/sec

  5 minute output rate 21000 bits/sec, 27 packets/sec

     121642981 packets input, 2246753017 bytes, 0 no buffer

     Received 183 broadcasts (0 multicast)

     0 runts, 0 giants, 0 throttles

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

     0 watchdog, 0 multicast, 0 pause input

     0 input packets with dribble condition detected

     124977329 packets output, 2804069558 bytes, 0 underruns

     14018 output errors, 271824 collisions, 0 interface resets

     0 babbles, 14018 late collision, 419821 deferred

     0 lost carrier, 0 no carrier, 0 PAUSE output

     0 output buffer failures, 0 output buffers swapped out

I have this problem too.
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Correct Answer by Paolo Bevilacqua about 6 years 7 months ago

100BaseFX can also be half-duplex. Some hubs used that many years ago. If you think about, even copper ethernet has separate wires for TX and RX, in that there is no difference from fiber.

And the errors are not even that many, one each 8500 good packets approx.

But in any case, the best thing is to set the devices in full-duplex.

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Leo Laohoo Thu, 04/15/2010 - 23:01

Half-duplex, 100Mb/s, media type is 100BaseFX

It's caused by the half-duplex.  Collisions tend to slow down your network as missed packets need to be re-transmitted.  Is this a 2924C?
piconet006 Fri, 04/16/2010 - 00:19

This is 24FX 3550C . End devices are electrical power system and and some are CCTV camera. They might be using half-duplex mode.

Giuseppe Larosa Fri, 04/16/2010 - 02:04

Hello,

Half-duplex, 100Mb/s, media type is 100BaseFX

for me something is going wrong half duplex makes sense over RJ-45 copper but over a fiber based link the only meaningful state is full duplex because we usually have one fiber for tx and one for rx.

100BaseFX should be full duplex only.

Hope to help

Giuseppe

Correct Answer
Paolo Bevilacqua Fri, 04/16/2010 - 02:29

100BaseFX can also be half-duplex. Some hubs used that many years ago. If you think about, even copper ethernet has separate wires for TX and RX, in that there is no difference from fiber.

And the errors are not even that many, one each 8500 good packets approx.

But in any case, the best thing is to set the devices in full-duplex.

piconet006 Sat, 04/17/2010 - 04:27

Should I use full-duplex mode if the end device is CCTV camera? Is there any preventive steps for this "high collisions" error? Any all of the advices are really help me to find out the problem but also got a lot of knowledge.

piconet006 Sat, 04/17/2010 - 07:36

Paolo,

Thanks a lot for your answer. Now I know what to do. Could you please tell me what can be happen on switch if that amount of collision? Anyway, thanks a lot.

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