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New Member

Collision Problem

I have a Catalyst 6009 connected to a 3640. Port 2/1 on the 6009 is configured at 10MB/half as is port E0/0 on the 3640. I'm getting a lot of collisions on both ports. I have swapped the cable, changed the port on the 6009 to port 2/5 and changed the port on the 3640 to port E1/0. Cleared the counters for the ports and still I'm seeing many collisions.

Any thoughts would be greatly appreciated.

10 REPLIES
New Member

Re: Collision Problem

What is a "high" number? You should calculate this as a percentage of total packets and realize that there will always be some number of collisions. I think the official Cisco position is no more than .1% of packets result in collisions.

New Member

Re: Collision Problem

Hi,

The issue here is of speed and duplex setting.

Try setting the Duplex setting in router E0/0 interface and catalyst port as 10Mbps full forcibly.

If your router IOS doesn't give this option under interface mode or global mode, try upgrading the IOS ( I know thats pretty unusual!!) to 12.1 train.

The solution has been tested.

Hope that helps.

Daipayan

New Member

Re: Collision Problem

8042527 packets input

736926 collisions

which works out to be 9.16%

I have tried setting both ports to 10/half and 10/full but get the same results. I guess I should open a TAC case to see what Cisco has to say.

Thanks for your help!

New Member

Re: Collision Problem

Try setting the duplex of both interfaces to full duplex. I believe collisions are normal on half duplex links.

--Kevin

New Member

Re: Collision Problem

I agree, full duplex the connection on the 3640 and the 6009. This also solved my issues as well.

New Member

Re: Collision Problem

To my understanding, the IOS supports 100MB/full duplex if I have those cards installed but I don't, I only have the 10MB cards installed that only support half-dulpex.

Purple

Re: Collision Problem

I have never seen a Cisco card that doesn't support full duplex unless you have an old hub . All Cisco's copper cards have the option of setting them to full duplex even they are single speed cards on the 6X00 series , change to full duplex will get rid of collisions ,collisions are a normal function on a half duplex link . The more traffic you have the more collisions you will have .

New Member

Re: Collision Problem

Thanks for your help. FYI...

According to Cisco, I need to get the (T) or "T-train" version of code on my router so it will support the full duplex function.

Jim

New Member

Re: Collision Problem

Jim,

Tell me more about that, did they also tell you which minimum version you should get? I would love to get the 3640's I have to run in FD mode.

Thanks, Maarten Sjouw.

New Member

Re: Collision Problem

I'm runnng the Enterprise/FW/IDS Plus IPSec 56 Feature Set. Based on the amount of memory that I have (16MB flash & 64MB dram), the latest image that I can run is 12.1(5)T9.

Hope this helps.

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