A vSphere distributed switch functions as a single switch across all associated hosts. This enables you to set network configurations that span across all member hosts, and allows virtual machines to maintain consistent network configuration as they migrate across multiple hosts.

vSphere Distributed Switch Network
A vSphere Distributed Switch network

Like a vSphere standard switch, each vSphere distributed switch is a network hub that virtual machines can use. A distributed switch can forward traffic internally between virtual machines or link to an external network by connecting to physical Ethernet adapters, also known as uplink adapters.

Each distributed switch can also have one or more distributed port groups assigned to it. Distributed port groups group multiple ports under a common configuration and provide a stable anchor point for virtual machines connecting to labeled networks. Each distributed port group is identified by a network label, which is unique to the current datacenter. A VLAN ID, which restricts port group traffic to a logical Ethernet segment within the physical network, is optional.

Network resource pools allow you to manage network traffic by type of network traffic.

In addition to vSphere distributed switches, vSphere 5 also provides support for third-party virtual switches. For information about configuring the Cisco Nexus 1000v switch, go to http://www.cisco.com/go/1000vdocs.