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

Answered Question
Aug 19th, 2009
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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?

Correct Answer by Leo Laohoo about 7 years 11 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
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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
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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.

Lucien Avramov Wed, 08/19/2009 - 19:27
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interesting i've never seen that before. what version of code are you running?

Correct Answer
Leo Laohoo Wed, 08/19/2009 - 18:56
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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.

Leo Laohoo Wed, 08/19/2009 - 21:53
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Thanks for the rating.

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