Sonu,
About a year ago someone asked the same question and this was the answer at that time:
The 3560-E and 3750-ES have a switching Fabric of 4 ports and each port is 32 gig. 128Gig
in total. One port is connected to the stack wise plus, One port is connected to the 2X
10 Gig ports, the other two ports are connected to two port Asics which provide 48 gig
access ports.
Switching fabric provides local switching in case of cat 3560-E 48port
48 gig + 20 gig ( uplinks) = 68gig which is the wire rate backplane.
Hope it helps,
Gary