UNCLASSIFIED My 2c worth is that all fibre patch panels should be crossed over, as the cables to the servers are straight through. All ours are here. We've had 1 instance where the contractor obviously lost concentration for a while and 1 pair out of 24 were straight through!
Fun happens when you patch to other patch panels. You need an odd number in the run, otherwise you need to swap the server cables. Greg. From: [email protected] [mailto:[email protected]] On Behalf Of Adam Levin Sent: Friday, 12 October 2012 9:54 AM To: Jeff Woolsey; [email protected] Subject: Re: [lopsa-tech] fibrechannel patch panels Yeah, thanks. I think it is very strange that nobody had solved this common problem, but we ended up breaking them apart and flipping the sides after all. It is rough with so many cables at once. Adam Jeff Woolsey <[email protected]> wrote: On 10/11/12 10:05, Adam Levin wrote: Here's the problem: when we run cables from HBAs (in hosts or in storage systems) direct to the switches, the Tx and Rx are correct. When the lightguide patch is in the middle, the Tx and Rx are reversed. Some time ago, almost ten years now, when we started hooking things up in a newly-renovated server room, it took a while to figure out which part of the storage path was borken. Turned out that the connections between patch panels was straight-through. What I'm not sure about is what is normal for this configuration? Do people normally buy "crossover" FC cables to use with a patch panel, or do people buy proper patch panels which "uncross" the streams? In my opinion, all duplex fiber should be crossover, even the runs in walls between patch panels. That way you have a net twist, everything has Rx connected to Tx. (You will run into a problem if you use any passive bulkheads (FDDI had some, SC could too)) If the panels are straight, then the conections can be kludged in one place (of four possibilities, since these were SC-LC cables) by unclipping either end (and not reclipping to make a straight cable), making the problem a little more noticeable. Alas I wasn't in charge of that room and nobody ever fixed the parity on the panels, as far as I know... IMPORTANT: This email remains the property of the Department of Defence and is subject to the jurisdiction of section 70 of the Crimes Act 1914. If you have received this email in error, you are requested to contact the sender and delete the email.
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