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Create a new port rule

Updated: January 21, 2005

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

To create a new port rule

  1. Open Network Load Balancing Manager.

  2. If Network Load Balancing Manager does not already list the cluster, connect to the cluster.

  3. Right-click the cluster, and then click Cluster Properties.

  4. Click the Port Rules tab.

  5. Click Add.

  6. Using information from the enabling and configuring checklist, specify values for the following:

    • Cluster IP address, which is the virtual IP address that you want this rule to apply to. Enter a specific virtual IP address to create a virtual cluster, or check All to apply the rule to all virtual IP addresses.

    • Port range

    • Protocols

    • Filtering mode and as appropriate, values for Affinity, and Load weight, and then click OK.


  • The number and type of rules must be exactly the same for each host in the cluster. This is best achieved by using Network Load Balancing Manager to configure port rules (see second note below). If you are using Network Load Balancing Manager, when you add additional hosts, they will automatically inherit the cluster port rules from the initial host.

    If a host attempts to join the cluster with a different number of rules, or with different rules from the other hosts, it is not accepted as part of the cluster. The rest of the cluster then continues to handle the traffic as before. At the same time, a message is entered into the Windows event log. When this happens, consult the event log to determine which host is in conflict with the other cluster hosts, resolve the conflict, and then restart Network Load Balancing on that host.

  • In order to allow Network Load Balancing to properly handle IP fragments, you should avoid using None when selecting UDP or Both for your protocol setting.

  • You cannot add more than 32 port rules to a Network Load Balancing cluster.


  • When using Network Load Balancing Manager, you must be a member of the Administrators group on the host that you are configuring, or you must have been delegated the appropriate authority. As a security best practice, consider using Run as to perform this procedure. If you are configuring a cluster or host by running Network Load Balancing Manager from a computer that is not part of the cluster, you do not need to be a member of the Administrators group on that computer. For more information, see Default local groups, Default groups, and Using Run as.

  • To start Network Load Balancing Manager, open a Command prompt. From the command window, type NLBMgr, and then press ENTER.

  • To start Network Load Balancing Manager, open a Command prompt. From the command window, type NLBMgr, and then press ENTER.

  • If all of your hosts are running a product in the Windows Server 2003 family, you can specify port rules to apply to only specific IP addresses. This is useful when creating virtual clusters. If you are not running a Windows Server 2003 family product, you must apply the port rules to all IP addresses. For more information about virtual clusters, see "Understanding Virtual Clusters."

  • The list of all currently installed port rules is sorted by port range.

  • The parameters set in the properties dialog box are recorded in the registry on each host.

  • Changes to Network Load Balancing parameters are applied when you click OK in the properties dialog box. Clicking OK stops Network Load Balancing (if it is running), reloads the parameters, and then restarts cluster operations.

  • To start Network Load Balancing Manager, open a Command prompt. From the command window, type NLBMgr, and then press ENTER.

  • To ensure that Network Load Balancing Manager is displaying the most recent host information, right-click the cluster and click Refresh. This step is necessary because the host properties that Network Load Balancing Manager displays are a copy of the host properties that were configured the last time Network Load Balancing Manager connected to that host. When you click Refresh, Network Load Balancing Manager reconnects to the cluster and displays updated information.

Information about functional differences

  • Your server might function differently based on the version and edition of the operating system that is installed, your account permissions, and your menu settings. For more information, see Viewing Help on the Web.

See Also

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