is there any alternate command to create sub interfaces with gig ports as it does not supports the command " int gig1/0/1.1 "
enter the fallowing commands hope it will be clear you,
Switch-01#switchport trunk encapsulation dot1q
Switch-01#switchport mode trunk
I don't think the 3750 support subinterfaces as per command:
You would usually communicate with subinterfaces on a router with a trunk port and specific vlans for each broadcast domain. Otherwise known as Router-On-A-Stick.
Got some more information from the configuration guide, that confirms my suspicion.
From the configuration guide:
"A routed port behaves like a regular router interface, except that it does not support VLAN subinterfaces."
Here is the link for the configuration guide:
Again your solution is Router-On-A-Stick, for inter-vlan communication, or SVIs.