This release contains these new switch features or enhancements:
Quality of service (QoS) egress priority queue on a port. Shaped round robin (SRR) services the priority queue until it is empty before servicing the other three queues. You enable the egress priority queue by using the priority-queue out interface configuration command.
QoS Differentiated Services Code Point (DSCP) transparency allows the user to prevent the switch from rewriting the DSCP field in the user IP packet when QoS is enabled.
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat3750m/12114ax/ol464603.htm