Fiber Port (notconnect)

[jeremiah.nelson]

Ok so I am not nearly as Cisco knowledgable as I want to be and probably less so about fiber but I have to start somewhere.

I have 2 Cisco 3750x with 2 sfp+ modules (SFP-10g-lr) that don't see each other.  The layout is like this:  switch A -> fiber jumper -> cassette -> line -> cassette -> fiber jumper -> switch B.  A colleague and I have tested the jumpers and the 12 physical pairs of both cassettes and all are working.  The sfp+ modules are known working. The switch ports are known working.  I cannot get link lights on the two ten gig fiber ports.  I have defaulted the ports just to get a link light of sorts and nothing.  I have shut and no shut on these ports and still nothing.  I know it looks like a layer 1 issue but I don't how else to confirm that layer 1 has connectivity.

I'm sure it's something that is a blatant oversight but I am pulling out my hair.  Any ideas?

Jeremiah Nelson

[coleman.j · Accepted solution]

Do you have a "crossover" somewhere so that tx from SFP A is going to Rx on SFP B, if you are usings all LC connectors you can (carefully) snap the fibers out of the bracket and reverse them (This was much easier to do with SC and ST connectors) 

[jeremiah.nelson]

I actually have 2 crossovers.  Both jumpers are "crossovers".  So for instance on the switch the blue plug is on the right and it goes in the cassette on the left.  On the other side it comes out the left on the cassette and the right on the cable.  So the end result is right side on switch A to right side on switch B and vice versa.

Jeremiah Nelson

[jeremiah.nelson]

I just went and checked the patch cable my colleague checked and it was a straight through.  Thank you for your help.  I knew it was something obvious. 

[coleman.j]

So 1 Crossover too many, The left side of switch a needs to go to the right side of switch b and vice versa.