I have to wonder whether there was something wrong (a weird incompatibility) in the design of the patch cables that you were using so that when you switched to another manufacturer's cable it started working.
This reminds me of a story that only readers of this posting would be likely to appreciate. I once spent a couple of months debugging a problem with a Codex stat mux that would crash once a week or so at one customer site in Italy. The field service guy recognized that the PTT had provided a very noisy circuit, so we started by plugging in a noise generator to see if we could recreate the problem. Sure enough, it was the line noise that provoked the crash, but we still didn't know why the box was crashing. Watching on a protocol analyzer, I figured out that the crash happened about once for every 60,000 bad packets! I woke up in the middle of the night with the solution. Wanna guess?
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This reminds me of a story that only readers of this posting would be likely to appreciate. I once spent a couple of months debugging a problem with a Codex stat mux that would crash once a week or so at one customer site in Italy. The field service guy recognized that the PTT had provided a very noisy circuit, so we started by plugging in a noise generator to see if we could recreate the problem. Sure enough, it was the line noise that provoked the crash, but we still didn't know why the box was crashing. Watching on a protocol analyzer, I figured out that the crash happened about once for every 60,000 bad packets! I woke up in the middle of the night with the solution. Wanna guess?