Troubleshooting Ethernet Interfaces

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Mar 5th, 2009
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I have a 6503 running 12.2(18)SXF5 with a SUP-720. In slot 3, we have a 16-port WS-6516A GBIC line card. In each port we have a WS-5486 GBIC plugged into it.

I cant get 2 of the gigabitethernet interfaces to come up. So, while the field techs troubleshoot the fiber patches, I wanted to try to run port diagnostics on my end. Is there a way to loopback an ethernet interface as we can with a serial interface? With a serial/T1 interface, for example, you can plug in a hard loopback plug with pins 1 looped to 4 and 2 looped to 5. Or you can run software loopbacks from the onboard CSU/DSU.

What about the ethernet port? Can I use a hard loopback plug? If so, what should the encapsulation be set for? Are there any software dignostics/loopback tests?

Im doing my own research on Cisco's website, but I thought I would put this question out to everyone for a possible quick answer and feedback.

Thanks, folks.

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Giuseppe Larosa Thu, 03/05/2009 - 08:01
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Hello Victor,

I would try by closing TX on RX at the end of the fiber pair

you may need

switchport nonegotiate

receiving its own keepalive should be fine after that

Hope to help



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