The Cisco Catalyst 3750-X Series and 3560-X Series Switches support four optional network modules for uplink ports. The default switch configuration doesn't include the uplink module; at the time of switch purchase the customer has the flexibility to choose from network modules
The SFP+ interface supports both 10GbE and GbE port, allowing customers to use their investment in GbE SFP and upgrade to 10GbE when business demands change, without having to do a comprehensive upgrade of the access switch.