Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

CRC error and collisions

We discover a incrasing problem ved CRC errors and Collisions on catalyst 2950 and catalyst 3560 connected to clients (PC?s)with Gigabit NIC. Gigabit NIC?s is common on all new PC?s. The NIC?S are forced to 100 Mb half duplex and newest drivers.

The configuration on switchport is as follow: 100 Mb half duplex

Anybody know why ?

1 ACCEPTED SOLUTION

Accepted Solutions
Silver

Re: CRC error and collisions

The matched duplex will elimiate the collision problem. But for the CRC, there may be another issue.

According to below link, CRC errors occur when a number of frames arrive with an invalid CRC.

CRCs on the Ethernet are usually an indication of cabling problems. Verify whether all network cable connections are clean, and ensure there is nothing that can cause electromagnetic interference on the cabling.

http://www.cisco.com/en/US/products/hw/wireless/ps441/products_tech_note09186a0080177aa0.shtml

Hope this helps.

6 REPLIES
Hall of Fame Super Bronze

Re: CRC error and collisions

Collisions and CRC are normal on Half Duplex connections. The question is, why are you forcing the speed/duplex to 100/Half Duplex ?

You should configure Auto/Auto at both ends.

New Member

Re: CRC error and collisions

Hi,

Here are Cisco's recommendations how to setup parameters on the link between switch and NIC.

http://www.cisco.com/warp/public/473/46.html#bk

//Mikhail Galiulin.

Silver

Re: CRC error and collisions

If you configure auto-auto but not negoiated w/ 100/full or 1000/full. You better manual configure both at same speed and full duplex. There may be some issue between switch and NIC to negoiate the correct dupelx.

New Member

Re: CRC error and collisions

If the duplex is manually set at 100/ full for both ends, what else can cause CRC errors?

I have an AIR-AP1220B that has CRC errors off of the F0 port (not the wireless), but the interface on the 3500XL switch it is connected to shows no errors.

Silver

Re: CRC error and collisions

The matched duplex will elimiate the collision problem. But for the CRC, there may be another issue.

According to below link, CRC errors occur when a number of frames arrive with an invalid CRC.

CRCs on the Ethernet are usually an indication of cabling problems. Verify whether all network cable connections are clean, and ensure there is nothing that can cause electromagnetic interference on the cabling.

http://www.cisco.com/en/US/products/hw/wireless/ps441/products_tech_note09186a0080177aa0.shtml

Hope this helps.

New Member

Re: CRC error and collisions

Thanks for the reply;

The WAP has been moved out of its original location and I'm testing it at my desk, so the change of location, and of course, cabling, may rule out those causes (I tried a crossover also, just to rule that out).

Right now I'm leaning toward hardware failure at the interface as the cause, by process of elimination; I guess that would mean device replacement if this isn't an RMA-covered device.

265
Views
7
Helpful
6
Replies