Aironet 2800 duplex mismatch on WLC 5520 with 8.5.160 and C2960X with 15.2(7)E0a

[wlcuser]

 I had running 40 Pieces of Aironet 2802I on a WLC 5520 with 8.5.160 temporary for an event.

I had on one port of an 2960X with SW 15.2(7)E0a the following issue:

%CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on GigabitEthernet1/0/8 (not half duplex), with AP_RES_101_2802I GigabitEthernet0 (half duplex).

The AP´s were deployed to six 2960X but the issue was on only one port of an 2960X although all switchports and all AP´s had the same identical configuration.

[wlcuser]

 I had running 40 Pieces of Aironet 2802I on a WLC 5520 with 8.5.160 temporary for an event.

I had on one port of an 2960X with SW 15.2(7)E0a the following issue:

%CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on GigabitEthernet1/0/8 (not half duplex), with AP_RES_101_2802I GigabitEthernet0 (half duplex).

The AP´s were deployed to six 2960X but the issue was on only one port of an 2960X although all switchports and all AP´s had the same identical configuration.

[Leo Laohoo]

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@wlcuser wrote:

I had on one port of an 2960X with SW 15.2(7)E0a

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First, try upgrading the firmware.  DO NOT use 15.2(7)E0a.  Use a different version. 

[Leo Laohoo]

I had on one port of an 2960X with SW 15.2(7)E0a

[wlcuser]

But 15.2.7E0a is the Cisco suggested version:

https://software.cisco.com/download/home/284795740/type/280805680/release/15.2.7E0a

Which should i use instead?

[Leo Laohoo]

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@wlcuser wrote:

Which should i use instead?

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15.2(7)E1

[Scott Fella]

Did you verify the cable run to the ap? If you swapped the ap to a known good one, did you see the same results?

[wlcuser]

No i did´nt, but the switchport was running on 1000Full with no errors and i had no traffic impact. Only the error message was in the log. And with sh cdp neighbors detail i saw the same error. I cannot reproduce or test anymore, it was for an event last week, the event is finished in the meantime and the AP´s are not active anymore.

I can test it at the next event, if it will appear again.

[Scott Fella · Accepted solution]

Seems to me that it’s a cabling issue, but until you perform some process of elimination, it’s all a guess.

[wlcuser]

Ok, i cannot do anymore right know, if ist will appears in the future i will try some elimination processes.