Cisco 3850 interface reliability and output drops

[carl_townshend]

Hi All

We have an issue with a 100Mbit connection to our other site.

We have a 100Mbit ethernet circuit plugged into a 3850-24 port switch.

On the interface I can see the reliability drops to 180/255, the interface also has output drops incrementing as well as output errors, the values on these are the same, how come the output errors are the same as the drops?

I am guessing the drops are due to congestion? but why has the reliability dropped? we have changed the port and cable to the NTE but it is still not reliable.

Also could I reconfigure to help the output drops? maybe increase the queue-limit / buffers?

Any ideas?

[carl_townshend]

Hi

The output is as above, that was with the cables replaced

cheers

[Leo Laohoo]

Carl,
Pair B is not complete. Please re-run the test.
Post the "sh version". I want to also see the uptime and the version.

[carl_townshend]

EUUK-HWE2-SERVER-SW#sh ver
Cisco IOS Software, IOS-XE Software, Catalyst L3 Switch Software (CAT3K_CAA-UNIV                                                                                                                                                             ERSALK9-M), Version 03.06.06.E RELEASE SOFTWARE (fc1)

EUUK-HWE2-SERVER-SW uptime is 11 weeks, 4 days, 5 hours, 45 minutes
Uptime for this control processor is 11 weeks, 4 days, 5 hours, 50 minutes
System returned to ROM by Power Failure at 13:47:49 UTC Mon Jul 31 2017
System restarted at 03:10:52 UTC Sun Jul 15 2018
System image file is "flash:cat3k_caa-universalk9.SPA.03.06.06.E.152-2.E6.bin"
Last reload reason: Power Failure

[Leo Laohoo]

Ok, 3.6.6 and uptime is very low.
The TDR should come up with Pair A & B with result.

[carl_townshend]

Hi

We are getting exactly the same thing on our other site with a similar setup, so it must me the output drops making the reliability of the interface to go down.

[Leo Laohoo]

Reliability is not "governed" or "dependent" by output drops. But output drops are fully dependent to reliability. If reliability drops, output drops increase.

[carl_townshend]

Hi
The output drops are increasing with the output errors being the same, with them being errors this will surely bring the reliability down ?

[Leo Laohoo]

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@carl_townshend wrote:
The output drops are increasing with the output errors being the same, with them being errors this will surely bring the reliability down ?

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Hmmmm ... You have a point there. 

The stack is running 3.6.6.  Try uprgrading to 3.6.8 or 3.6.9.