How to Add or Modify Virtual Networks on a Host
Applies To: Virtual Machine Manager 2008, Virtual Machine Manager 2008 R2, Virtual Machine Manager 2008 R2 SP1
This topic provides step-by-step instructions for adding a new virtual network or modifying an existing virtual network on a host.
For Hyper-V hosts, VMM makes use of the virtual networks in Windows Server 2008 or Windows Server 2008 R2 virtualization, which are capable of using virtual local area networks (VLANs). A VLAN provides a method for creating independent logical networks within a physical network. This helps ease network administration by separating the logical segments of a LAN that should not exchange data, and this is done by using a LAN that is configurable rather than hardwired. Because a VLAN configuration is flexible, computers can easily be moved and still maintain their network configurations.
For virtual machines on Hyper-V hosts, each port corresponds to a virtual network adapter on the virtual machine. You can configure VLANs by assigning a numerical value called a VLAN identifier (VLAN ID) for the port on the virtual machine. Internally, all network traffic originating from that port is tagged with this VLAN ID. VLAN-enabled networks, both virtual and physical, route all tagged network traffic based on the VLAN ID of the tag. This ensures that network traffic for a VLAN is routed only to and from ports on the same VLAN. For more information about configuring virtual networks in VMM, see Configuring Virtual Networks in VMM.
To view a graphical representation of the virtual networking configuration on a host, in Hosts view, right-click the host, and then click View networking. The Networking window displays the following:
Virtual networks on the host
Virtual network adapters of virtual machines on the host and which networks that they are attached to
Physical network adapters on the host and which virtual networks and external networks that they are bound to
You can position the pointer over objects in the diagram to display information about the object, and you can click an object to view its connection path in the network. You can also change the scope of the diagram by adding other hosts, switching views, copying the diagram to the clipboard, and changing the scale.
To add or modify a virtual network on a Hyper-V host
In Hosts view, navigate to the host group that contains the host, and then, in the results pane, double-click the host.
Click the Networking tab and then do one of the following:
Click Add to create a new virtual network.
In the Virtual Networking list, click an existing network that you want to modify.
In the Virtual network details area, do the following:
In the Name box, type a name for the virtual network.
In the Network tag box, type or select the network tag you want to use.
In the Description box, type a description.
In the Network bindings area, do the following:
Click Private network to create an internal network that allows virtual machines on the host to communicate with each other but not with the host.
Click Internal network to create an internal network that allows virtual machines on the host to communicate between each other and with the host, and then, if you want to enable virtual machines to access the host through a VLAN, do the following:
Select the Access host through a VLAN check box.
In the VLAN ID box, select the VLAN ID that you want to use.
Click Physical network adapter to create an external network that is bound to a physical network adapter so that virtual machines on the host can access a physical network, and then do the following:
If you do not want the virtual machines on the host to access the host (the default setting), clear the Host access check box.
Important
If the physical network adapter is the host’s only connection to VMM, clearing the Host access check box breaks that connectivity. The only way to restore connectivity will be to modify the configuration.
If you want to enable virtual machines to access the host through a VLAN, ensure that the Host access check box is selected, and then in the VLAN ID box, select the VLAN ID that you want to use.
Note
VMM 2008 R2 allows you to take advantage of network optimization capabilities that are available on Hyper-V hosts that are running Windows Server 2008 R2. If network optimization has been enabled on a Windows Server 2008 R2 host, VMM automatically discovers this. A read-only property above the Host access check box indicates whether or not network optimization is available. The network optimization features are enabled in Windows Server 2008 R2. For more information about network optimization and the hardware that supports it, see the Windows Server 2008 R2 documentation.
Click Add, and then in the Switch binding dialog box do the following:
In the Host network adapter list, click a network adapter for this virtual network.
If you want to enable VLANs on this network adapter, select the Enable VLANs on this connection check box, and then do one of the following:
Click Access mode, in the VLAN ID box, select the VLAN ID that you want to use.
Click Trunk mode, then do one of the following:
Select the Trunk all VLAN IDs check box.
In the VLAN ID box, select a VLAN ID that you want to use, and then click Add. You can add multiple VLAN IDs.
Important
Before enabling VLANs on this network adapter, ensure that there will be at least one other network adapter available for communications between the host and the VMM server.
To add or modify a virtual network on a Virtual Server host
In Hosts view, navigate to the host group that contains the host, and then, in the results pane, double-click the host.
Click the Networking tab and then do one of the following:
Click Add to create a new virtual network.
In the Virtual Networking list, click an existing network that you want to modify.
In the Virtual network details area, do the following:
In the Name box, type a name for the virtual network.
In the Network tag box, type or select the network tag you want to use.
In the Description box, type a description.
In the Network bindings area, do the following:
In the Physical network adapter list, click a network adapter on the host to create an external network, or click None (Guests Only) to configure an internal network.
If you are creating a new virtual network, in the Virtual network path box, type a path on the host where the virtual network configuration (.vnc) file will be stored, or click Select to browse to a destination folder.
Note
You can use one folder to store multiple network configuration (.vnc) files. After the virtual network has been created, you cannot modify this path.
If you want to enable a virtual DHCP server, in the Virtual DCHP area, select the Enable virtual DHCP server check box, and then click Configure.
In the Virtual DHCP Server Settings dialog box, configure the DHCP settings as you would for a physical computer. For more information about DHCP settings, see DHCP server role: Configuring a DHCP server (https://go.microsoft.com/fwlink/?LinkId=103037).
Configuring Common Virtual Networks on Host Clusters
If a virtual network will be used by highly available virtual machines on a host cluster, you must configure it to be a common virtual network on all hosts in the cluster.
For a virtual network to be considered common by VMM and available to highly available virtual machines, each virtual network in the host cluster must meet the following requirements:
The virtual network name must be identical on each host in the cluster. Virtual network names are case-sensitive, so the cases of all characters must match.
The host network adapters to which the virtual network is attached on each host in the cluster must have the same location.
The virtual network must have the same tag on each host in the cluster.
To ensure that the virtual networks are recognized as common and are available to highly available virtual machines on the cluster, after you attach host network adapters on each clustered host to the virtual networks, refresh the host cluster. Then check the Networks tab in the host cluster properties to verify that the networks have been added to it.