Most Hyper-V or VMware vSphere hosts take advantage of virtual LAN tagging. VLAN tagging allows you to configure virtual machines to run on multiple VLANs over shared switch ports. In order to use these features, you must configure the physical network switch ports for trunking. My Hyper-V 2012 R2 hosts have four interfaces on two network adapters and many of the interfaces are dedicated to virtual machine traffic. These interfaces are connected to highly available Cisco Catalyst 2960-S switches via Ethernet. Here are the basic Cisco IOS commands necessary to enable a switch port to pass traffic on multiple VLANs.
If you leave out the allowed VLAN statement, it will pass all VLANs by default. The native VLAN statement tells the switch port which VLAN to use when the traffic is not tagged, which may be necessary in some cases.
For HP Procurve network switches and some other network switch brands, you can achieve the same result by using the "Tag" and "Untag" commands. In the switch port configuration, you would leave one VLAN untagged, which has same effect as the native VLAN statement in Cisco IOS. The rest of the VLANs being used for virtual machine traffic would be set to "Tagged" mode. In Cisco terms, the untagged VLAN would be similar to the native VLAN and the tagged VLANs would be allowed to pass.