TCAMINTERRUPT

The name of the blog comes from an odd error I got on a customer 4510R-E switch running 12.2(50)SG1, the log showed:

%C4K_SWITCHINGENGINEMAN-4-TCAMINTERRUPT: flCam0 aPErr interrupt. errAddr: 0x2464 dPErr: 1 mPErr: 0 valid: 1

%C4K_SWITCHINGENGINEMAN-4-TCAMINTERRUPT: flCam0 aPErr interrupt. errAddr: 0x2464 dPErr: 1 mPErr: 0 valid: 1

%C4K_SWITCHINGENGINEMAN-4-TCAMINTERRUPT: flCam0 aPErr interrupt. errAddr: 0x2464 dPErr: 1 mPErr: 0 valid: 1

%C4K_SWITCHINGENGINEMAN-4-TCAMINTERRUPT: flCam0 aPErr interrupt. errAddr: 0x2976 dPErr: 1 mPErr: 0 valid: 1

The device was not affected, even though according to the docs, this is supposed to mean "A parity error in a TCAM entry was detected. Contents of the log register are printed out Software will automatically perform error recovery on the defective TCAM entry"

It the end it was the result of the following IOS bug:

CSCsv17545 %C4K_SWITCHINGENGINEMAN-4-TCAMINTERRUPT: flCam0 aPErr interrupt
Externally found severe (Sev2) bug: R-Resolved

Symptoms
Under normal operation we see the following messages appearing frequently in the logs:

%C4K_SWITCHINGENGINEMAN-4-TCAMINTERRUPT: flCam0 aPErr interrupt. errAddr: 0x2947 dPErr: 1 mPErr: 0 valid: 1

%C4K_SWITCHINGENGINEMAN-4-TCAMINTERRUPT: flCam0 aPErr interrupt. errAddr: 0x2B59 dPErr: 1 mPErr: 0 valid: 1

Conditions
The issue appears to happen under normal operation, so far this has been observed after around two weeks of uptime, but needs to be confirmed.

Workaround
None At Present.

Solution
Upgrade software to IOS version 12.2(52)SG or later OR 12.2(50)SG4 or later.