[c-nsp] CRC Errors on Ethernet Router

[danger will]

It sometimes happens when one side of teh connection has hardcoded the speed and duplex and the other one doesn't . Check how the duplex was negotiated (should see a-half) , you should see both CRC and inbound erros incrementing in this case 

--- On Wed, 2/23/11, alex nyagah <alex.nyagah.k at gmail.com> wrote:

From: alex nyagah <alex.nyagah.k at gmail.com>
Subject: Re: [c-nsp] CRC Errors on Ethernet Router
To: "Kasper Adel" <karim.adel at gmail.com>
Cc: "cisco-nsp at puck.nether.net" <cisco-nsp at puck.nether.net>
Date: Wednesday, February 23, 2011, 4:46 PM

Thanks so much, I now have a point to start checking...
alex


On Wed, Feb 23, 2011 at 5:37 PM, Kasper Adel <karim.adel at gmail.com> wrote:

> Hi,
>
> Usually when Cyclic Redundancy Check (CRC) errors are incrementing in the
> show interface command output, it indicates that the cyclic redundancy
> checksum generated by the originating LAN/WAN device does not match the
> checksum calculated from the data received. On a LAN, this usually indicates
> noise or transmission problems on the LAN interface or cable. A high number
> of CRCs is usually the result of collisions or a station transmitting bad
> data.
>
> So we can safely assume that CRCs are a very critical alarm and it can not
> be ignored so I don’t think there should be a threshold in general, the NMS
> should monitor interfaces for CRCs and if the number increments then an
> immediate check is needed, we are talking on the core links here. So we cant
> wait till the counter increments.
>
> Once we have CRCs, then we have a bad cable, port or router and this needs
> immediate attention.
>
> Regards,
> Kim
>
>
> On Wed, Feb 23, 2011 at 3:53 PM, Harold 'Buz' Dale <buz.dale at usg.edu>wrote:
>
>> First thing I would do would be to check for a duplex mismatch and then
>> check the wiring (either by replacing the cable if it's a simple patch or
>> using a cable tester over the span.) You might also just physically trace it
>> and see if someone decided to hang a fluorescent light off of it or
>> something too.
>> Luck,
>> Buz
>>
>> -----Original Message-----
>> From: cisco-nsp-bounces at puck.nether.net [mailto:
>> cisco-nsp-bounces at puck.nether.net] On Behalf Of alex nyagah
>> Sent: Wednesday, February 23, 2011 6:19 AM
>> To: cisco-nsp at puck.nether.net
>> Subject: [c-nsp] CRC Errors on Ethernet Router
>>
>> Hi All,
>>
>> I am noting CRC errors on my Ethernet port on my cisco router, what could
>> it
>> be causing it..
>>
>> --
>> **
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