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 ...