Which feature of vSphere networking restricts the inbound and outbound network bandwidth of a group of virtual machines?

Differentiated Services Code Point (DSCP) is a packet-marking standard used to signal QoS priority to physical network devices; it tags traffic but does not itself enforce or restrict bandwidth within vSphere.

NetFlow is a traffic monitoring and export protocol that collects IP flow statistics for analysis by external tools; it observes traffic but does not control or limit bandwidth.

Traffic Shaping is a port group policy in vSphere that controls network bandwidth by configuring average bandwidth, peak bandwidth, and burst size limits on a virtual switch port group. It is the only vSphere networking feature specifically designed to cap and shape the rate of traffic flowing to and from virtual machines. It can be applied on both vSphere Standard Switches and Distributed Switches.

Port Mirroring duplicates traffic from selected ports to a designated monitoring port for packet capture and analysis; it has no mechanism to restrict or shape bandwidth.