I have three Cisco 3750G (#1, #2 and #3) stacked as core switch. Each switch has fiber ports downlink with Cisco 2960.
The problem is I cannot ping the SVI interface from 2960 if it's connected to the #2 switch with fiber cable. it works properly in last week before this problem happen.
It works if I uplink the 2960 with copper cable to any core switch, it also works if I connect 2960 to the fiber port of #1 or #3. It looks all fiber ports on the #2 switch cannot route data .
I tried to reload the #2 switch individually. 2960 can ping SVI for few minutes after reboot, then the problem comes again.
Is it a hardware problem or configuration issues?
I'm appreciated for you replay. This problem was by replacing #2 swtich with a spare one, without changing the stack.
I think It should be hareware problem on Fiber data process module.