Late collision errors

[ocaluag]

there were a lot of "late collision" experienced on the ethernet port of my router which is configured for HSRP as Active. I have swapped the available ethernet port of my router and still the same. This is connected to a switch. Any idea for cause ? can the switch port causes the prob.? What are some physical test i need to perform ?

thanks

cro

[okopp]

i think, that late collisions are caused collisions after first 64 bytes,this mean that the cable is too long. You could check cable lenght

[zhengliu]

Check the cable, connector and other physical medias between the two device.

Second, check the duplex mode, use full-duplex on both side of the link can decrease collisions.

[ali-franks]

Ethernet is CSMA/CD so you will see collisions anyway but the total should be 0.1 percent or less of the total output packets.

Ali

[okopp]

Ali,

Oliver wrote "late collision" it isn't the same as collision

Olda

[ali-franks]

So he did- apologies

[MickPhelps]

Late collisions are caused by either violating the 5-4-3 rule, cable lengths exceeding 100 meters, or duplex mismatches.

My money is on the duplex mismatch.

You will probably find the other interface is running full duplex and is seeing many CRC errors.

Set them both to be either full or half.

Mick.

[ocaluag]

thanks for the information

[vlausell]

HOWEVER, the 5-4-3 rule only applies to repeaters and hubs.  Many people don't know about this bc we don't use them anymore.  I had to do some research to figure out what you meant by that rule. Interesting though.  Always good to know a little bit of history. Thanks. 

[Joseph W. Doherty]

"Many people don't know about this bc we don't use them anymore."

Indeed they don't.  Just as possible even more don't know the 5-4-3 rule applies to 10 Mbps Ethernet.

100 Mbps Ethernet had more stringent rules, and had Class I and Class 2 repeaters.

NB:  Of course, knowing this is a bit easier when you have actually used/built such networks.