Connecting a 3560 to a 4912

[stevenmedeiros]

I'm a little baffled with this one...

I connected a 3560, using an SFP GBIC and SC to LC Fiber cable, to a 4912 switch - worked fine. I disconnected the 3560 from the network for reasons not relevant to this discussion.

I connected the same 3560 with no config changes to the same 4912, using the same GBICS and Fiber cable cables. This time I get a "errdisabled link-flap" error on the uplink interface. I changed the speed on the interface to 1000 full and re-enabled the interface. The interface came up, but on the 4912 switch - the config shows that the interface is not connected.

Any suggestions?

Thanks

[stevenmedeiros]

More information.....

If I plug a 2948 switch using the same GBICs, same fiber cables, and same port on the 4912 - the 2948 gets connectivity no problem.

In addition, this is a flat network.

Thanks in advance for your help!