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New Member

crc errors on 6009

I have a remote site that is connected to our main network via a MC3810 router. A 6009 switch is connected to the router at this remote site.

Every now and then I get crc errors on the port that goes to the ethernet interface of the router. I have to reboot the switch, about once a week, in order to get those clients back up on the network.

I know rebooting the switch every time isn't the answer. How can I begin to troubleshoot why this is happening?


New Member

Re: crc errors on 6009

It would help to know how many CRCs you're getting. Is every packet corrupted at this point, or is data still moving. Also, are there errors on the 6000's ethernet interface as well?

You may want to check for duplex mismatches. You'll see CRCs on the full-duplex side and late collisions on the half-duplex side. Are there other errors on either side besides CRCs? Interface resets? Does the ethernet cable run past anything that could generate EMI every few weeks? Lots of things to check :)


New Member

Re: crc errors on 6009


Thanks for the response.

I'm new to the Cisco arena. I just recently acquired my CCNA. So, some of this I don't know.

I do know the following.. Maybe this will help further explain my problem..

1. Data does not flow from the router to the switch or from the switch to the router. From a client I can't ping the E0 on the router. From the router, I can't ping any clients or the switch.

2. When I console into the router, I have UP/UP on E0 and S0.

3. When I console into the 6009 it gives me a message about CRC errors on port 47. This is the port that connects to the router.

4. Port 47, on the 6009, is set for auto on duplex and speed. I did this because I don't believe I have the option of setting duplex or speed on E0 of the MC3810.

5. Both Cisco devices are pretty much on top of each other. Mounted in the rack. No major electrical devices nearby. Just a power strip to plug the two devices into.

So, with that, I just reboot the switch. About a minute or two later all is well.

With my lack of knowledge, at this time, that's about all I know how to do. That's why I've posted a thread.


New Member

Re: crc errors on 6009

If your ethernet port on your 3810 is regular ethernet (10Mbps/Half duplex), hardcode the switch to 10/half.

Are you getting errors on the ethernet port on the 3810 of any kind?

Change the cable between the devices... you probably already have, but it needs to be said.

post a show int from the router for your e0 interface. Also, post the show port from the 6000 switch for that port number.