Strange. All of our siemen panels are simplex lc fibers at the back so we don't run into this problem. On Oct 11, 2012 8:36 PM, "Robinson, Greg" <[email protected]> wrote:
> *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. **** > > _______________________________________________ > Tech mailing list > [email protected] > https://lists.lopsa.org/cgi-bin/mailman/listinfo/tech > This list provided by the League of Professional System Administrators > http://lopsa.org/ > >
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