SplitRx mode uses multiple physical CPUs to process network packets received in a single network queue. This feature can significantly improve the network performance of certain workloads.

These workloads include:

• Multiple VMs on one ESXi host, all receiving multicast traffic from the same source.
• Traffic via the DVFilter API between two VMs on the same ESXi host.

vSphere 5.1 and later versions automatically enable this feature for a VMXNET 3 virtual network adapter (the only adapter type on which it is supported). They do so when they detect that a single network queue on a physical NIC is both heavily utilized and servicing more than eight clients (that is, VMs or vmknic) that have evenly distributed loads.