Configure Hardware Load Balancing for Hub Transport Servers


Applies to: Exchange Server 2010 SP3, Exchange Server 2010 SP2

You can configure a hardware load balancing solution to distribute non-Exchange messages among your Hub Transport or Edge Transport servers. To learn more about load balancing SMTP traffic, see Understanding SMTP Failover and Load Balancing in Transport.


Using a load balancing solution to handle message traffic between the Exchange servers in your organization isn't supported. You must exclude message traffic between Exchange servers from any load balancing solution you deploy in your environment.

Looking for other management tasks related to handling SMTP traffic? Check out Managing Message Routing.


Step 1: Use DNS to create the SMTP namespace

You first need to create an SMTP namespace that will be used for Windows Network Load Balancing (NLB). The following steps apply to the Active Directory-integrated Windows Domain Name System (DNS). If you use a third-party DNS server, refer to that documentation to create the necessary DNS records with the attributes shown in this procedure.

To perform this step, the account you use must be delegated membership in the DNS Admins group or the Domain Admins group.

  1. Log on to a computer that has the DNS management console installed, click Start, point to Administrative Tools, and then click DNS to open DNS Manager.

  2. If you aren't connected to the DNS server of your domain, use the following steps to connect to a DNS server. If you are connected to the correct server, go to step 3.

    1. On the Action menu, select Connect to DNS Server.

    2. Click The following computer, type the name of the DNS server to which you want to connect, and then click OK.

  3. On the menu, click View, and then select Advanced mode unless it's already selected.

  4. Expand the server name, and then expand the Forward Lookup Zones node.

  5. Right-click the zone in which you want to create the SMTP namespace, and then select New Host (A).

  6. Specify the host name for the SMTP namespace and the associated IP address, and then set Time to live (TTL) to 5 minutes. For example:

    • Name   mail   

    • IP Address


      You will notice that when you type the host name, the FQDN box is automatically updated. Make sure that the FQDN box shows the exact name you want to use for your SMTP namespace.

  7. Click Add Host.

  8. Click OK in the confirmation window, and then click Done.

  9. Close DNS Manager.

Step 2: Use your vendor documentation to configure the virtual SMTP service on your hardware load balancing solution

For the steps required to create and configure the virtual SMTP service on the hardware load balancing solution used within your organization, see the hardware load balancing documentation provided by your vendor. Most hardware load balancing vendors have detailed documentation about how their product works with Exchange 2010 including steps about how to create a virtual SMTP service that can distribute incoming SMTP traffic among the Hub Transport servers in your organization.

For more information about Exchange 2010 server load balancing solutions, see Microsoft Unified Communications Hardware Load Balancer Deployment.

Step 3: Use Network and Sharing Center to add additional IP addresses to your Hub Transport servers

This step should be completed for each Hub Transport server participating in the hardware load balancing solution.

To perform this step, the account you use must be delegated membership in the Server Operators group or the local Administrators group.

  1. Click Start, click Control Panel, and then double-click Network and Sharing Center.

  2. Click Manage network connections.

  3. Right-click the connection for the internal network, and then select Properties.

  4. Double-click Internet Protocol Version 4 (TCP/IPv4).

  5. Click the Advanced button.

  6. Under IP addresses, click Add.

  7. Enter the IP address and subnet mask to which your hardware load balancer will direct SMTP traffic.

  8. Click Add, and then click OK twice to close the property page for Internet Protocol Version 4 (TCP/IPv4).

  9. Click Close to exit the property page for the connection.

Step 4: Use the EMC to create a Receive connector

This step should be completed for each Hub Transport server participating in the hardware load balancing solution.

You need to be assigned permissions before you can perform this procedure. To see what permissions you need, see the "Receive connectors" or "Receive connectors - Edge Transport" entry in the Transport Permissions topic.

  1. In the console tree, navigate to Server Configuration > Hub Transport.

  2. In the result pane, select the server on which you want to create the connector, and then click the Receive Connectors tab.

  3. In the action pane, click New Receive Connector. The New SMTP Receive Connector wizard opens.

  4. On the Introduction page, enter a name for the connector, and then select Custom in the Select the intended use for this Receive connector box. Click Next.

  5. On the Local network settings page, select (All Available IPv4), and then click Edit.

  6. In the Edit Receive Connector Binding window, select Specify an IP address, and then enter the virtual IP address of the Hub Transport server that you added to this Hub Transport server in step 3. Click OK.

  7. On the Local network settings page, enter the SMTP namespace you created in step 1 in the Specify the FQDN this connector will provide in response to HELO or EHLO box, and then click Next.

  8. On the Remote network settings page, leave the default values, and then click Next.

  9. On the New connector page, click New.

  10. Click Finish to exit the wizard.

Other Tasks

After you configure hardware load balancing for Hub Transport servers, you may also want to do the following:

  • If the Hub Transport server needs to accept messages from non-authenticated sources, make sure Anonymous users is enabled on the new Receive connector. For more information, see step 6 in Configure Receive Connector Properties.

  • If the Receive connector also needs to be used for relaying purposes, you need to perform additional configuration. For example, you may have line-of-business (LOB) applications that need to relay messages through the local Exchange organization for delivery to external recipients. For more information, see Allow Anonymous Relay on a Receive Connector. Also, review the Exchange Server Team Blog article Allowing application servers to relay off Exchange Server.


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