IFPCEENLBCluster::VIP property

Applies to: desktop apps only

The VIP property gets the virtual IP address of the Network Load Balancing (NLB) cluster.

This property is read-only.


  BSTR *pbstrVIP
' Data type: String

Property VIP( _
  ByVal pbstrVIP As BSTR _
) As String

Property value

String that specifies the virtual IP address of the NLB cluster.

Error codes

This property method returns S_OK if the call is successful; otherwise, it returns an error code.


This property is read-only. Its default value is an empty string. The virtual IP address of the NLB cluster can be modified by calling the SetVIPAndMask method or by importing the value of this property from a saved configuration.

Note  If you programmatically change the primary virtual IP address of an NLB cluster by importing this setting from a stored configuration when one or more additional virtual IP addresses are configured in the AdditionalVIPs property, IP address conflicts between array members are inevitable.

Forefront TMG requires every network adapter in an NLB cluster to have a dedicated IP address and a virtual IP address. When the virtual IP address of an NLB cluster is configured in Forefront TMG, Forefront TMG integration with NLB sets this IP address as the second IP address of all the network adapters attached to the applicable network in the array. Forefront TMG also sets the first IP address in the TCP/IP properties of these network adapters as the dedicated IP address provided it is not equal to the IP address specified in the VIP property.

The DNS name of the array, which is the DNSName property of the FPCArray object, can be mapped in the DNS zone files used by clients to the virtual IP addresses of all the NLB clusters that are configured in the array followed by the default IP addresses of the array members. When an NLB cluster is enabled, clients in the applicable network that send requests to the DNS name of the array would use its virtual IP address because it is the first available IP address to which the DNS name is resolved. When the cluster is disabled, clients would use the first available dedicated IP address.

For SecureNAT clients sending requests that are not handled by the Forefront TMG Web proxy to an NLB cluster, the default gateway should be set to the virtual IP address of the cluster.


Minimum supported client

Windows Vista

Minimum supported server

Windows Server 2008 R2, Windows Server 2008 with SP2 (64-bit only)


Forefront Threat Management Gateway (TMG) 2010





See also




Build date: 7/12/2010