Lenovo RackSwitch G8264 Application Manual page 330

The outer vNIC group VLAN is not removed by the switch before the packet
egresses any internal port or external uplink port. For untagged packets sent by the
server, the uplink NIC uses this outer tag to switch the packet to destined VLAN.
The shared mode is useful in cases where the multiple vNIC groups need to share
an uplink port. The vNIC group tag defines the user VLAN. Following is an use
case:
An ESX server is presented with eight vNICs used with four virtual switches of the
ESX host and with no tagged port groups. A pair of odd/even vNICs is placed
within each virtual switch. On the G8264, four vNIC groups are created and the
desired VLAN for each vNIC group is configured. For example, if vNIC group 1 on
the G8264 has four interfaces: 1.1, 2.1, 3.1, 4.1. vNIC group 1 is configured with
VLAN 10. Packets coming from any VM connecting with the virtual switch that
VMNIC 2 and 3 will be assigned with VLAN 10. These packets go out the uplink
with VLAN 10 tag. The upstream switch sends these packets to the desired
destination on VLAN 10.
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G8264 Application Guide for ENOS 8.4