NLB::How to configure the balancer for web front servers

The NLB is the software balance solution from Microsoft, I use it for staging, developer or testing environments normally, while for pre-production and production ones I always head on for the hardware ones; F5, Netscaler …

The configuration is easy, but for virtual environments it´s important to know how to configure it.

The first thing is to decide if we´ll use the same IP address for the NLB or if we´ll use an IP address for the virtual cluster (NLB) and each server will use their own IP for the communication between each other. I would go for the second one, it´s the one I´m used to choose.

Scenario:

In the scenario of today we do have a SharePoint farm with 3 servers (2 WFE + SQL), all based on Hyper-V technology. Each WFE server has 1 NIC. Let´s call the WFE1.contoso.com / WFE2.contoso.com.

We have an IP address for the virtual cluster (NLB): 172.22.25.12

The following Site collections must answer to the IP:

http://devlab.contoso.com

http://devMysite.contoso.com

• First step.

For virtual machines under Hyper-V technology you must enable the spoofing of the MAC, it will not work otherwise. In the Hyper-V console, select the virtual machine, settings, and look for the network adapter you might use for NLB. Under the MAC address there´s a check to enable "Enable spoofing of the MAC address".  The Virtual machine must be stopped to change this parameter.

• Ensure the feature (NLB) is enabled on the WFE server >> Click Start, click Administrative Tools, and then click Network Load Balancing Manager. If the option does not appear enable the feature following the steps below:

1. Click Start, point to Administrative Tools, and then click Server Manager. In the Features Summary area of the Server Manager main window, click Add Features.
   -- or --
   In the Customize this server area of the Initial Configuration Tasks window, click Add Features.

2. In the Add Features Wizard, select the checkbox next to Windows Network Load Balancing.

3. Click Install.

Pasted from <http://technet.microsoft.com/en-us/library/cc771300(v=ws.10).aspx>

• Creating a virtual cluster (NLB):

1. To open Network Load Balancing Manager, click Start, click Administrative Tools, and then click Network Load Balancing Manager.

2. Right-click Network Load Balancing Clusters, and then click New Cluster.
3. In Host, enter the name of the host, and then click Connect. In our scenario: WFE1.contoso.com

4. Select the interface that you want to use with the cluster, and then click Next.

5. In Cluster IP Addresses, click Add to enter the cluster IP address that is shared by every host in the cluster: in our case 172.22.25.12

6. In Cluster operation mode, click Unicast (by default)
7.  right-click the new cluster, and then click Add Host to Cluster. At this time we´ll add the second server: WFE2.contoso.com

If you check the IPs in the Network properties or query ipconfig (cmd) it will appear that the NIC have 2 IPs, the original and the new for the NLB.

• How can I get to resolve the IP address?  You must manually register the NLB cluster name in DNS by using a host (A) or (AAAA).In our case:

New registers  Host (A):

 Nombre : devlab.contoso.com

IP : 172.22.25.12

 Nombre : devmysite.contoso.com

IP : 172.22.25.12

This is an easy configuration that works in this scenario, for other configurations you might review the specifications.

More info at http://technet.microsoft.com/en-us/library/cc771300%28v=ws.10%29.aspx