I have 1 x WS-C3750X-48T-S switch and 4 x WS-C3560X-24T-L switches .
All are using 4 port 1 GbE SFP Module (C3KX-NM-1G) and SFP Transceiver Module SMF (GLC-LH-SMD).
My connection is simple , each 4 x 3560 switches will connected to 3750 ,distance about 2km and using single mode fiber link.
Problem is all 3560 fiber ports have light , but no light on 3750 fiber ports.
Then I test out by following ways,
1. tested 3560 switches putting side by side , connecting with working fiber patch cables , fiber ports are all working.
2. checked all the Modules (C3KX-NM-1G) and (GLC-LH-SMD) on 3560 and all are working fine.
3. tested 3560 and 3750 switches putting side by side, connecting with working fiber patch cables , no light on 3750 and light are blinking on 3560.
4. I have one more spare unit of 3750 and and tested with 3560 , same result ,no light on 3750 and light are blinking on 3560.
5.tested two 3750 switches putting side by side, connecting with working fiber patch cables , no light on both 3750 .
I only set name and ipaddress on all the switches , most of the config are default setting.
These switches and modules are tested in one year ago with same config and all links are working fine.
Then deliver to onsite store and keep it for one year.
Now installation in process and facing this problem .
is it 3750 switch hardware porblem or config ?
Please help ...!
