Which settings are required for virtual machine guest tagging for VLAN 100 in a vSphere 5.x environment?
A. Port Group configured for VLAN 100, physical switch configured as a VLAN trunk
B. Port Group configured for VLAN 4095, physical switch configured as a VLAN trunk
C. Port Group configured for VLAN 100, physical switch configured for VLAN 100
D. Port Group configured for VLAN 4095, physical switch configured for VLAN 100
Correct Answer: B
Explanation/Reference:
The question states VM guest tagging therefore the vSwitch has to allow all VLANs (4095) and the physical switch must be trunked.
VLAN ID 0 (zero) Disables VLAN tagging on port group (EST Mode)
VLAN ID 4095 Enables trunking on port group (VGT Mode)
More Info.
The answer comes from the VMWare network guide found here:
http://www.vmware.com/files/pdf/virtual_networking_concepts.pdf
This link shows how to configure the VGT mode, and the use of port 4095:
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1010733
Virtual switch tagging (VST mode) - This is the most common configuration. In this mode, you provision one port group on a virtual switch for each VLAN, then attach the virtual machine’s virtual adapter to the port group instead of the virtual switch directly. The virtual switch port group tags all outbound frames and removestags for all inbound frames. It also ensures that frames on one VLAN do not leak into a different VLAN.
Use of this mode requires that the physical switch provide a trunk.
Virtual machine guest tagging (VGT mode) - You may install an 802.1Q VLAN trunking driver inside the virtual machine, and tags will be preserved between the virtual machine networking stack and external switch when frames are passed from or to virtual switches. The format for the header of a packet tagged in this way is shown in Figure 3.
Use of this mode requires that the physical switch provide a trunk.
External switch tagging (EST mode) - You may use external switches for VLAN tagging. This is similar to a physical network, and VLAN configuration is normally transparent to each individual physical server.
There is no need to provide a trunk in these environments
and the article on how to configure VGTS…
Configuring Virtual Guest VLAN tagging (VGT) mode on a vNetwork Distributed Switch (1010733)
Purpose
This article describes the concept and configuration of Virtual Guest VLAN tagging (VGT) mode on ESX 4.x. Resolution
Note: For additional information on dvPortGroup configuration, see vNetwork Distributed PortGroup (dvPortGroup) configuration (1010593).
This is a new Virtual Network Adapter, also known as Advanced VMXNET. It is based on Enhanced VMXNET introduced in ESX 3.5, it provides these new features:
•IEEE 802.1Q VLAN tagging
•No more need for e1000 Driver inside of a virtual machine
•VLAN tagging and tag removal offloading
•Only one VLAN per NIC for Windows
•TCP Segmentation Offloading for IPv4 and IPv6
•TCP and UPD Checksum Offloading for IPv4 and IPv6
•MSI (Messaged Signalled Interrupt) and MSI-X support (subject to guest kernel support)
•Receive Side Scaling (supported in Windows Vista, 2008 and any other system using NDIS 6.x)
•VMXNET 3 is the new “state of the art” Virtual Network Adapter.
To modify and add vNetwork Distributed Port Groups (dvPortGroup):
1.In vCenter, click Home > Inventory > Networking.
2.Right-click on dvPortGroup and choose Edit Settings.
3.Under dvPortGroup > Policies > VLAN, these settings can be specifed:
VGT – VLAN Guest Tagging
VLAN Trunking – Physical equivalent to: VLAN in Trunk/Tagged mode
Standard vSwitch equivalent to: VLAN ID set to 4095
Note: Distributed Switch Only specifies the range of VLANs to trunk, to improve security.
Explanation/Reference:
The question states VM guest tagging therefore the vSwitch has to allow all VLANs (4095) and the physical switch must be trunked.
VLAN ID 0 (zero) Disables VLAN tagging on port group (EST Mode)
VLAN ID 4095 Enables trunking on port group (VGT Mode)
More Info.
The answer comes from the VMWare network guide found here:
http://www.vmware.com/files/pdf/virtual_networking_concepts.pdf
This link shows how to configure the VGT mode, and the use of port 4095:
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1010733
Virtual switch tagging (VST mode) - This is the most common configuration. In this mode, you provision one port group on a virtual switch for each VLAN, then attach the virtual machine’s virtual adapter to the port group instead of the virtual switch directly. The virtual switch port group tags all outbound frames and removestags for all inbound frames. It also ensures that frames on one VLAN do not leak into a different VLAN.
Use of this mode requires that the physical switch provide a trunk.
Virtual machine guest tagging (VGT mode) - You may install an 802.1Q VLAN trunking driver inside the virtual machine, and tags will be preserved between the virtual machine networking stack and external switch when frames are passed from or to virtual switches. The format for the header of a packet tagged in this way is shown in Figure 3.
Use of this mode requires that the physical switch provide a trunk.
External switch tagging (EST mode) - You may use external switches for VLAN tagging. This is similar to a physical network, and VLAN configuration is normally transparent to each individual physical server.
There is no need to provide a trunk in these environments
and the article on how to configure VGTS…
Configuring Virtual Guest VLAN tagging (VGT) mode on a vNetwork Distributed Switch (1010733)
Purpose
This article describes the concept and configuration of Virtual Guest VLAN tagging (VGT) mode on ESX 4.x. Resolution
Note: For additional information on dvPortGroup configuration, see vNetwork Distributed PortGroup (dvPortGroup) configuration (1010593).
This is a new Virtual Network Adapter, also known as Advanced VMXNET. It is based on Enhanced VMXNET introduced in ESX 3.5, it provides these new features:
•IEEE 802.1Q VLAN tagging
•No more need for e1000 Driver inside of a virtual machine
•VLAN tagging and tag removal offloading
•Only one VLAN per NIC for Windows
•TCP Segmentation Offloading for IPv4 and IPv6
•TCP and UPD Checksum Offloading for IPv4 and IPv6
•MSI (Messaged Signalled Interrupt) and MSI-X support (subject to guest kernel support)
•Receive Side Scaling (supported in Windows Vista, 2008 and any other system using NDIS 6.x)
•VMXNET 3 is the new “state of the art” Virtual Network Adapter.
To modify and add vNetwork Distributed Port Groups (dvPortGroup):
1.In vCenter, click Home > Inventory > Networking.
2.Right-click on dvPortGroup and choose Edit Settings.
3.Under dvPortGroup > Policies > VLAN, these settings can be specifed:
VGT – VLAN Guest Tagging
VLAN Trunking – Physical equivalent to: VLAN in Trunk/Tagged mode
Standard vSwitch equivalent to: VLAN ID set to 4095
Note: Distributed Switch Only specifies the range of VLANs to trunk, to improve security.
