Understanding Network Location and Tags in SCVMM

Network Location: This represents the logical network identity for an individual physical network adapter. The Network Location Awareness (NLA) service provider on the Windows-based virtual machine host is used to return this information for every active network connection. NLA will first identify the logical network by DNS domain name. If that fails, information stored in the registry is used. If this information is not available then the subnet address is used. VMM stores the identified logical network as part of the virtual machine host object. You can query the network adapter of the virtual machine host for this information. When deploying a virtual machine to a host, VMM will match the desired logical network with the actual logical network advertised by the host. You can also override the default logical network discovered using NLA and specify your own logical network string

Network Tag: You can decorate a virtual network with additional metadata called Network Tag. This property is user specified and so is not automatically populated as Network Location is. Tagging a virtual network is important if you need to differentiate two networks that return the same logical network information.

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For more information see the following topics in the SCVMM 2008 TechNet library:

How to Configure Network Adapters for a Virtual Machine

Network location. This setting is used by placement to determine equivalence between virtual networks across different hosts. Virtual networks determine their location from the host network adapter associated with them. You can link multiple host network adapters to multiple virtual networks and have one address set as the location. This allows a virtual machine to move and retain the correct connectivity.

Network tag. A tag is a virtual network property that allows you to define precise constraints on the network access of a virtual machine. For example, a host may have two network adapters, both with connectivity to the same network, but one dedicated to a Backup network. The Backup virtual network can be configured to have "Backup" as its tag.

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Frequently Asked Questions: Virtual Networks in VMM

How are network locations created, and can I change them?

For Windows-based computers in an Active Directory domain, network locations are automatically discovered as the Domain Location. For network adapters that are disconnected, are not connected to a domain, or are on a host that is not in a domain, the network location is empty. You can configure different network locations for physical network adapters on a host by configuring settings on the Hardware tab of the Host Properties dialog box or by using the Set-VMHostNetworkAdapter cmdlet with the –NetworkLocation parameter in the Windows PowerShell – Virtual Machine Manager command shell.

During virtual machine placement, how does VMM consider the networking needs of a virtual machine?

While creating or deploying a virtual machine, you can specify the network location to which to connect the virtual machine. During virtual machine placement, VMM checks the virtual machine’s networking requirements against the networks configured on all managed hosts. Any host that does not have a network adapter configured with the specified location receives a zero star rating.

ref: Mike Briggs and http://blogs.technet.com/b/scvmm/archive/2010/05/10/understanding-network-location-and-tags-in-scvmm.aspx