[c-nsp] 2651xm packet loss with 200 ft ethernet link

[Andy Dills]

I'm having a weird problem that I can't quite seem to wrap my head around.

I have customer who has a 2651XM that we're hooking up to a Level3 
(copper) ethernet circuit. Because of the distance between our telco 
handoff and his rack, he has about 200 feet. Which shouldn't be a problem. 

However, we were seeing tremendous packet loss. After determining the 
errors were coming from this end, and testing and replacing everything in 
the path, we finally tried moving the router into the telco handoff room 
so we could try to eliminate a lot of variables. With a short patch cable, 
it worked fine, no packet loss.

So, we made a 200 ft cable to simulate the issue, and hooked it up to the 
router while it sat next to the Level3 handoff...major packet loss again. 
We tried the other fastethernet interface on the 2651...same problem.

However, if I take that same cable and terminate it into one of our 7200s, 
we get zero packet loss.

In sum:

This 2651xm with long cable, major packet loss
This 2651xm with short cable, works fine
Our 7200 with the same long cable, works fine

What's going on here? Is the controller in the 2651xm failing? Perhaps not 
producing enough voltage?

Thanks,
Andy

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Andy Dills
Xecunet, Inc.
www.xecu.net
301-682-9972
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