Now that I've focused on the architecture behind a Network Load Balancing cluster, I can show you how to actually create a Network Load Balancing cluster.
Note: I recently witnessed a situation in which an administrator attempted to make a single server a part of both a Network Load Balancing cluster and a traditional cluster. A single server cannot be a member of two different types of clusters at the same time, because the two clustering methods use the server's network interface card (NIC) differently.
This article assumes that all your cluster nodes have two NICs installed, and that you've already installed Windows Server 2003 on all the nodes. I'm also assuming that each cluster node already has IIS installed and configured to host a copy of your Web application. To begin the configuration process:
- Select the Network Load Balancing Manager command from the Administrative Tools menu. Windows will nowlaunch the Network Load Balancing Manager console.
- Select the Network Load Balancing Clusters container in the console's upper left corner.
- Select the New command from the Cluster menu. This will cause Windows to open the Cluster Parameters dialog box, shown in Figure A.
- Fill in the IP Address field with the IP address that will be shared by all the nodes in the cluster. After the configuration process is complete, configure your DNS server to direct inbound requests for the Web application to this address.
- Once you fill in the IP address, enter a corresponding subnet mask.
- Now enter the cluster's fully qualified domain name. (This is the URL that Web users will enter to get to your Web application.) Note: Typing your fully qualified domain name into the Full Internet Name field alone is not enough for Internet users to reach your site. Your DNS server must also contain a record that links the fully qualified domain name to the cluster's IP address.
Figure to come
As you can see in the above figure, the Network Address field is filled in automatically. The number in this field represents the MAC address that will be shared by all nodes in the cluster.
Next you'll have to choose whether the cluster will operate in unicast or multicast mode. Assuming the cluster has two NICs, it is usually best to select unicast mode.
The final option in this dialog box is the Allow Remote Control check box. It's up to you to decide whether or not you want to be able to remotely control cluster nodes. To enable remote control, select this check box and enter a remote access password. Note: Any time you enable remote control on a publicly accessible server, security issues are involved.
Click Next and you'll be taken to a screen that allows you to enter additional cluster IP addresses. Enter any additional addresses you want to use, then click the Next button. You should now see the Port Rules dialog box shown in the figure below.
Figure 2 to come
This dialog box lets you specify which ports and protocols the Network Load Balancing service should distribute among cluster nodes. As you can see, the default port rule is designed to take any inbound traffic across any port, and balance it across the cluster nodes.
It is generally considered bad form to have a rule that accepts any unanticipated types of traffic. Because we are creating this cluster as a way of distributing traffic related to a Web application, let's assume that the only legitimate traffic coming into the server should be HTTP traffic flowing across TCP port 80. That being the case, click the Edit button and change the port range so that the From and To fields both contain the number 80. Likewise, the Protocols section should be set to TCP, as shown in the figure below. Click OK to continue.
Figure 3 to come
You'll now be returned to the Port Rules screen. Click Next to reveal the Connect dialog box, which lets you enter the names of any servers in the cluster. For now, just enter the name of the server you're configuring. Click the Connect button. All the server's network interfaces will be listed at the bottom of the screen. Select the interface you want to use for the cluster. Click Next.
At this point, you'll see the Host Parameters dialog box, which allows you to set a unique IP address for the selected host. Assuming the host has already been configured with a unique static IP address, you shouldn't have to do anything here. Still, it's a good idea to check the Priority drop-down list to make sure the host has indeed been assigned a unique host identifier number.
Click the Finish button. You'll be taken back to the main Network Load Balancing Manager screen. You should now see the specified host listed below the cluster container, as shown in the figure below. You can add additional nodes to the cluster by repeating the above process.
Figure 4 to come
The next article in this series will show you how to monitor and manage the cluster.
About the author: Brien M. Posey, MCSE, is a Microsoft Most Valuable Professional for his work with Windows 2000 Server, Exchange Server and IIS. He has served as CIO for a nationwide chain of hospitals and was once in charge of IT security for Fort Knox. He writes regularly for SearchWinComputing.com and other TechTarget sites.
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