With VMware Distributed Virtual Switch or DVS, one of the new features in the upcomming VMware VI4, allows you to create Virtual Switchs at a cluster level and assign ESX Servers to them. Up to now, in VI3, virtual switches can only be created at a host level, and if in a DRS/HA Cluster, these virtual switches are normally configured the same across all hosts. With DVS, you only have to create a virtual switch once and assign it to all hosts. It also allows you to migrate virtual machines on existing virtual networks to a new network all with a few clicks!