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

Differentiated Services Code Point (DSCP) marks packet headers with priority values to request QoS treatment from upstream physical network devices, but it does not itself enforce or restrict bandwidth on the vSphere host.

NetFlow is a network monitoring protocol that exports flow-level traffic data to an external collector for analysis; it observes and reports traffic but does not restrict or shape bandwidth.

Traffic Shaping is a vSphere networking policy applied at the port group level that restricts both inbound (ingress, available on vDS) and outbound (egress) bandwidth for virtual machines by specifying average bandwidth, peak bandwidth, and burst size. It directly controls how much network throughput a group of VMs can consume, making it the correct feature for bandwidth restriction.

Port Mirroring (SPAN) duplicates traffic from specified ports to a monitoring destination for packet capture and analysis; it has no mechanism to limit or restrict bandwidth.