Can you detect wiring issues (xover vs straight) via IOS?

Answered Question
Aug 19th, 2009

Folks, given two switchports from different switches connected to each other, is there any way to detect pins/wiring is wrong based on output of 'show controller' or another IOS command?

I have this problem too.
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Correct Answer by Leo Laohoo about 7 years 5 months ago

Depending on the model of the appliance, you can also use the Time Delay Reflectometer (TDR) cable test.

test cable-diagnostics tdr command reference

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/software/release/12.1_19_ea1/command/reference/cli2.html#wp2253269

Hope this works.

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Lucien Avramov Wed, 08/19/2009 - 18:35

wiring / pins wrong can be detected in the show ip interface brief. If an interface shows down / down, that means you have a cabling issue.

If the link shows up, it means layer 1 is OK.

news2010a Wed, 08/19/2009 - 19:26

Well, in the case today I witnessed that the logic "interface down/down = layer 1 issue" did not work. It appeared as :

FastEthernet3/2 is up, line protocol is down (notconnect)

and the thing was definitely a bad cable.

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