I am dealing with a point to point gig connection Provider is using a single mode fiber and connecting to a Ciena 311v device (1550). Then they are handing it off to us as multi mode (850). This connection was connected to a 2960 switch using a fiber sfp running 12.xxx IOS. I took this and connected it to a 4948E switch with the same SFP but running 15.xxx IOS I did not get a link light. When I connect that 4948E to another Cisco device using the same sfp and cable link comes up. (Note: This is a Tengig port supports 1Gig and 10 Gig)
I connect it back to 2960 and link comes up. Next I upgrade the IOS on the 2960 to 15.0 and no link again. I downgrade the IOS and it works. Provider is telling me with absolute confidence that the issue is with the Cisco.
Any thoughts, experience with Ciena 311v and connecting it to a Cisco switch particularly 4948E with 1/10gig ports?
