This is a very weird issue and I'd like to see what you all think about it.
I'm attempting to connect a 2960x 24p switch to a pair of 3750G 12p SFP switches running HSRP. The 2960 has a fiber link (GLC-LH-SMD modules in all devices) between each switch:
2960 1/0/25 --> 3750G 1/0/11
2960 1/0/27 --> 3750G 1/0/11
Each interface is configured as a trunk with dot1q and a native vlan. This is where it gets interesting. After connecting the fiber, link lights on the 2960x are green and the interfaces show up/up. CDP neighbors shows nothing. Spanning Tree shows FWD.
On the 3750G side (both switches same output), no link light, down(not connect) and no spanning tree info. CDP neighbors shows nothing on int 1/0/11.
2960x running 15.0(2a)EX5
3750G running 12.2(58)SE2
The 3750G is working fine, no other issues and a number of dual homed switches connected on other interfaces.
I've never experienced one side of a link show green while the other is not connect. I shot light over the fiber connection to visually verify that the connections are correct and they are indeed connected to the correct interfaces.
Any Ideas on what I can check? Thank you in advance.