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Collisions on 3550


3550 has got lot of collisions on ports.

3,4 ports have got this message :

Error Message ETHCNTR-3-HALF_DUX_COLISION_EXCEED_THRESHOLD: Collision at [chars] exceed threshold. Consider as loop-back.

like show on this url

and the port pass in shutdown mode.

To reactivate the port, we pass the command : "no shutdown".

Follow informations about one of trouble ports.

FastEthernet0/6 is up, line protocol is up

Hardware is Fast Ethernet, address is 0009.43e3.e906 (bia 0009.43e3.e906)

Description: Vers Hub_10_12_5_126_LAN

MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,

reliability 255/255, txload 4/255, rxload 1/255

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

Half-duplex, 10Mb/s

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

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

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

Last clearing of "show interface" counters 6d23h

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 0 bits/sec, 0 packets/sec

5 minute output rate 170000 bits/sec, 39 packets/sec

2896528 packets input, 1608516928 bytes, 0 no buffer

Received 39267 broadcasts, 0 runts, 0 giants, 0 throttles

1237 input errors, 1237 CRC, 0 frame, 0 overrun, 0 ignored

0 watchdog, 468 multicast, 0 pause input

0 input packets with dribble condition detected

16467500 packets output, 3535857678 bytes, 6277 underruns

4 output errors, 670428 collisions, 2 interface resets

0 babbles, 0 late collision, 168682 deferred

0 lost carrier, 0 no carrier, 0 PAUSE output

6277 output buffer failures, 0 output buffers swapped out

We can't reduce this collisions on this ports and we search a solution to avoid the passage on shutdown mode.

Has someone got a idea ?

Thank You.

Community Member

Re: Collisions on 3550

First check the configuration of the device that is plugged into the port with exdessive collisons. Make sure it and the ports are set to autodetect speed and duplex. If not, change them both and reboot the device.

If this doesn't take care of the problem, take the device that is plugged into the port with excessive collisions and move it to a different port. If the collisions follow the device, replace the NIC in the device.

Community Member

Re: Collisions on 3550

Hello John and thank You for your answer.

The speed and the duplex are forced to 10 and half in both sides.

Behind the 3550, there are 3 Hub Cascade 3-Com.

We have already move the port into another but this problem persist.

The problem is present on 3,4 ports aleatory.

We can have no problem (no shutdown) during 1 week and many shutdown on this 3550 during

short time.

I hope that i'm explicit =)

All ideas are welcome.

Community Member

Re: Collisions on 3550

If you can't reduce the high number of collisions that you are experiencing on your Hub stack, my recommendation would be to break the 3Com stack. Uplink each of the hubs individually to a seperate port on the switch and eliminate the problem.

Hope it helps.


Community Member

Re: Collisions on 3550

Hello Bob and thank you for your help,

It's not really possible to break down the stacked Hub 3Com

because there is no port available on the 3550 :|.

We search a solution which is the cheapest.

All advices are excepts.

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