Lenovo Flex System Fabric CN4093 Application Manual page 233

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Figure 27. Outer and Inner VLAN Tags
vNIC-Capable Server
OS/Hypervisor
Regular
NIC attached outer
VLAN ID
vNIC group VLAN ID
Outbound
Packet
Outer tag sets vNIC;
NIC strips outer tag
Inbound
Packet
Within the CN4093, all Layer 2 switching for packets within a vNIC group is based
on the outer vNIC group VLAN. The CN4093 does not consider the regular, inner
VLAN ID (if any) for any VLAN‐specific operation.
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 is 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 (four from bay 7 and four from bay 9)
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 CN4093, four
vNIC groups are created and the desired VLAN for each vNIC group is
configured. For example, if vNIC group 1 on the CN4093 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 (vNIC 1.1, 2.1, 3.1, and
4.1 on bay 7 and bay 9) 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.
Ports with
vNICs
NIC
Switching uses outer tag;
Ignores regular VLAN
Switching uses outer tag;
Ignores regular VLAN
Lenovo Switch Ports without
Switch does not
strip outer tag
Switch retains
outer tag
Chapter 16: Virtual NICs
vNICs
233