6880 silent traffic loss

[aleks]

Friends help with solving the problem!

There are two c6880X-LEs and they work as a VSS pair. Scheme is below – vss.png

Cisco IOS Software, c6880x Software (c6880x-ADVENTERPRISEK9-M), Version 15.5(1)SY4, RELEASE SOFTWARE (fc4)

Technical Support: http://www.cisco.com/techsupport

Copyright (c) 1986-2019 by Cisco Systems, Inc.

Compiled Mon 02-Sep-19 06:25 by prod_rel_team

ROM: System Bootstrap, Version 15.1(02)SY01 [ Rel 1.1], RELEASE SOFTWARE

The following problem occurs steadily every three months:

Silent Traffic loss, with no drop counters increment on any interfaces and no user facing exception/syslog. Shut/No-shut of the interface will not resolve the issue. And after that, other ports start to fly out periodically ... a day, a week after the first time. The problem is on both chassis.

Workaround:

A reload of the impacted module or move physical link and configuration from non-working port to different port.

According to the description, we fall under the following bugs: CSCvi51975; CSCvg81219; CSCve08995;

Maybe someone has a solution?

Rebooting is not an acceptable solution to the problem.

No way to contact TAC.

[aleks]

6880 experts where are you? :)))

[marce1000]

 - Your issue is clearly filed under at least one of the mentioned bug reports, therefore in my opinion if you can not work with TAC on it then you are dead-locked.

 M.

[aleks]

Totally agree with you! Therefore, I am here to find out if anyone has encountered such a problem and what was the solution.

[marce1000]

 - If the issue becomes mentioned in an authoritative bug report from Cisco ,  the solution then is to upgrade to one of the Known Fixed Releases, if mentioned in the bug report. If that information is not provided in the bug report  , then the only other solution is to work with TAC and look for alternatives.

 M.

[devilstide]

We are experiencing the same issue, we are on 15.5(1)SY6(listed as a fixed release) - still appears to be dropping traffic from the WLC's which one of the modules is hooked up to.

It's funny how it's very selective on which traffic to drop - I haven't confirmed this yet - but it appears to latch onto specific sources/destinations as we have been experiencing intermittent and odd issues here and there on a few WLC's connected there.

We are likely due a reload, but I have also raised a TAC case to rectify this.

[Giuseppe Larosa]

Hello @devilstide ,

>> t's funny how it's very selective on which traffic to drop - I haven't confirmed this yet - but it appears to latch onto specific sources/destinations 

Likely the bug is related to corruption of some CEF entries that are black holed.

Hope to help

Giuseppe

[devilstide]

Hi Giuseppe,

Would you have any examples on how I would be able to see these corrupted CEF entries and perhaps a way to clear them manually(without rebooting the switch)?

Thanks,

Ivars