VLAN Configuration on Virtual Switch, Physical Switch, and Virtual Machines

This article describes the various VLAN tagging methods used with ESX.

Virtual LAN (VLAN) implementation is recommended in ESX networking environments because:    

It integrates ESX into a pre-existing network It secures network traffic

It reduces network traffic congestion iSCSI traffic requires isolated network

Resolution

There are three methods of VLAN tagging that can be configured on ESX:   

External Switch Tagging (EST) Virtual Switch Tagging (VST) Virtual Guest Tagging (VGT)

External Switch Tagging

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All VLAN tagging of packets is performed on the physical switch.

ESX host network adapters are connected to access ports on the physical switch. The portroups connected to the virtual switch must have their VLAN ID set to 0. For more information, see Sample configuration - ESX connecting to physical switch via VLAN access mode and external switch VLAN tagging (EST Mode) (1004127). See the following example snippet of code from a Cisco switch port configuration:

switchport mode access switchport access vlan x

Virtual Switch Tagging

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All VLAN tagging of packets is performed by the virtual switch, before leaving the ESX host.

The ESX host network adapters must be connected to trunk ports on the physical switch.

The portgroups connected to the virtual switch must have an appropriate VLAN ID specified.

For more information, see Configuring a VLAN on a portgroup (1003825) . For a sample of VST, see Sample configuration of virtual switch VLAN tagging (VST Mode) (1004074).

See the following example snippet of code from a Cisco switch port configuration:

switchport trunk encapsulation dot1q switchport mode trunk

switchport trunk allowed vlan x,y,z spanning-tree portfast trunk

Note: The Native VLAN is not tagged and thus requires no VLAN ID to be set on the ESX portgroup.

Virtual Guest Tagging

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All VLAN tagging is performed by the virtual machine.

You must install an 802.1Q VLAN trunking driver inside the virtual machine, VLAN tags are preserved between the virtual machine networking stack and external switch when frames are passed to/from virtual switches. Physical switch ports are set to trunk port.

For more information, see Sample configuration of virtual machine VLAN tagging (VGT Mode) (1004252).

See the following example snippet of code from a Cisco switch port configuration:

switchport trunk encapsulation dot1q switchport mode trunk

switchport trunk allowed vlan x,y,z spanning-tree portfast trunk

For additional information on these configurations, see VMware ESX Server 3: 802.1Q VLAN Solutions.