I ran into a problem a few weeks ago and am still trying to figure out why either the 3560 switch or our Cacti syslog server did not alert us when one of our ports was experiencing heavy CRC and Input errors.
I had upgraded the IOS to 12.2(55)SE6 and rebooted the switch. About a week later, someone was troubleshooting why print jobs were having problems printing to a high speed printer. When I looked at the interface it showed a few thousand CRC and Input errors. I cleared the counters and had them print again and watched as the CRC and Input errors went up. When I did a "show log" there were no error messages. Looking at our Cacti Syslog there were also no errors present for the past 6 months.
We found that the device on the port was set to auto speed and duplex and the switch port was at 100/Full. Once we got them to match the problem was resolved, but we were left wondering why we never got any alerts.
We also have some 3548 and 3550 model switches that Cacti picks up %LINK-4-ERROR for any ports that show CRC and Input errors. I did some research and it appears that the 3560 switches do not have the LINK facility code. I believe it has been replaced with a PHY link code but I'm not sure. We do have some "%PHY-4-EXCESSIVE_ERRORS: Excessive FCS, data, or idle word errors found" but they are all for 3750 switches. I could not find any 3560 that had alerted for that error or the LINK error.
I also tripped port security on the 3560 switch just to make sure that it was reporting correctly to Cacti and that alert did show up.
My question is how do I get a 3560 switch to alert in the logging buffer for CRC/Input/FCS errors? Also, does anyone know how I can generate CRC and Input errors on purpose for testing? I tried mismatching the speed/duplex/Auto and only got collissions, no CRC or Input errors.
Thank you in advance for any help you can provide.
I am trying to find out how to get a 3560 switch to alert for CRC and Input errors or if it already does this, what does the alert look like? I've been searching through cisco documentation and have been unsuccesful finding an answer.
3550 and 3548 switches log an alert in syslog like the following:
Oct 16 06:15:27.001 Eastern: %LINK-4-ERROR: GigabitEthernet0/5 is experiencing errors
Unfortunately it doesn't seem like the 3560 switches do this.