Re: [c-nsp] CRC Errors on Ethernet Router
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.nyaga...@gmail.com wrote: From: alex nyagah alex.nyaga...@gmail.com Subject: Re: [c-nsp] CRC Errors on Ethernet Router To: Kasper Adel karim.a...@gmail.com Cc: cisco-nsp@puck.nether.net cisco-nsp@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.a...@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.d...@usg.eduwrote: 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-boun...@puck.nether.net [mailto: cisco-nsp-boun...@puck.nether.net] On Behalf Of alex nyagah Sent: Wednesday, February 23, 2011 6:19 AM To: cisco-nsp@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.. -- ** ___ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/ ___ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/ ___ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/ ___ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
[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.. -- ** ___ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
Re: [c-nsp] CRC Errors on Ethernet Router
On 23/02/2011 9:19 PM, alex nyagah wrote: Hi All, I am noting CRC errors on my Ethernet port on my cisco router, what could it be causing it.. duplex mismatch, bad cable, cosmic rays. Send though a show interface from both ends. -James. ___ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
Re: [c-nsp] CRC Errors on Ethernet Router
duplex? On 23.02.2011 12:19, alex nyagah wrote: Hi All, I am noting CRC errors on my Ethernet port on my cisco router, what could it be causing it.. ___ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
Re: [c-nsp] CRC Errors on Ethernet Router
On Wed, 23 Feb 2011, alex nyagah wrote: I am noting CRC errors on my Ethernet port on my cisco router, what could it be causing it.. You have to provide more information. Is this copper or fiber, what speed, what is at the other end, how long is the cable etc. -- Mikael Abrahamssonemail: swm...@swm.pp.se ___ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
Re: [c-nsp] CRC Errors on Ethernet Router
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-boun...@puck.nether.net [mailto:cisco-nsp-boun...@puck.nether.net] On Behalf Of alex nyagah Sent: Wednesday, February 23, 2011 6:19 AM To: cisco-nsp@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.. -- ** ___ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/ ___ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
Re: [c-nsp] CRC Errors on Ethernet Router
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.d...@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-boun...@puck.nether.net [mailto: cisco-nsp-boun...@puck.nether.net] On Behalf Of alex nyagah Sent: Wednesday, February 23, 2011 6:19 AM To: cisco-nsp@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.. -- ** ___ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/ ___ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/ ___ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
Re: [c-nsp] CRC Errors on Ethernet Router
Thanks so much, I now have a point to start checking... alex On Wed, Feb 23, 2011 at 5:37 PM, Kasper Adel karim.a...@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.d...@usg.eduwrote: 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-boun...@puck.nether.net [mailto: cisco-nsp-boun...@puck.nether.net] On Behalf Of alex nyagah Sent: Wednesday, February 23, 2011 6:19 AM To: cisco-nsp@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.. -- ** ___ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/ ___ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/ ___ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
