How-To: Configure Network Load Balancing (NLB) with Two Network Adapters
1. Assign appropriate IP addresses to each NIC, placing the NICs in separate
subnets. Rename the first NIC “Public“ and the second to “Admin“, do this for each machine.
* Node1 -
o "Public" NIC
* IP address: 10.10.10.11
* Subnet: 255.255.255.0
* Gateway: 10.10.10.1
* DNS: as appropriate
o "Admin" NIC
* IP address: 192.168.1.1
* Subnet: 255.255.255.0
* Gateway: N/A
* DNS: N/A
* Node2 -
o "Public" NIC
* IP address: 10.10.10.12
* Subnet: 255.255.255.0
* Gateway: 10.10.10.1
* DNS: as appropriate
o "Admin" NIC
* IP address: 192.168.1.2
* Subnet: 255.255.255.0
* Gateway: N/A
* DNS: N/A
2. On the "Public" NICs, click "Advanced" and add an additional IP address
as the Virtual IP Address which clients will connect to from the Public
network (i.e. - 10.10.10.169)
3. Install "Network Load Balancing" as an additional service from the
"Public" adapter properties.
* Click "Install.." and then select "Service" in the upper-window and
click "Add."
* Select "Network Load Balancing" in the upper-window and click "OK"
* Answer any prompts and provide the correct path to installation media (Windows 2000 installs only).
4. Once NLB is installed, return to the Properties page for the "Public"
NIC and select the check-box next to "Network Load Balancing." This
enables the service globally.
5. Next, select the item "Network Load Balancing" and click "Properties"
6. Configure the NLB Cluster properties according to your parameters,
using the following example steps as a guide.
* Node1 -
o "Public" NLB Cluster Parameters tab
* Primary IP address: 10.10.10.169
* Subnet: 255.255.255.0
* Full Internet Name mail.clusterhelp.com
o "Public" NLB Host Parameters tab
* Priority: 1
* Dedicated IP address: 10.10.10.11
* Subnet: 255.255.255.0
* Node2 -
o "Public" NLB Cluster Parameters tab
* Primary IP address: 10.10.10.169
* Subnet: 255.255.255.0
* Full Internet Name mail.clusterhelp.com
o "Public" NLB Host Parameters tab
* Priority: 2
* Dedicated IP address: 10.10.10.12
* Subnet: 255.255.255.0
7. MultiCast support can be optional in this configuration, though I would not recommend it.
8. You can also now take time to create a static Host record (A record) in
your scenario's DNS infrastructure to provide appropriate name resolution
to the NLB cluster name (i.e. - mail.clusterhelp.com or just mail).
9. Your NLB cluster should be up and running after the nodes converge.
10. An external client should now be able to ping the IP address of the
NLB cluster (i.e. - 10.10.10.169) as well as each of the individual node
addresses (i.e. - 10.10.10.11 & 10.10.10.12).
11. Many good diagnostic commands can be found by typing "wlbs /?" in a
command window. For example, "wlbs query" shows the status and
convergence state of the cluster. If you are running Windows Server 2003 (any version expect SBS) you can use the graphical Network Load Balancing Manager - I love this tool.
12. IMPORTANT NOTE: In this configuration, each individual node is NOT
able to ping the other node's Public physical IP address (i.e - 10.10.10.11
cannot ping 10.10.10.12 and vice-versa). I believe this is expected
behavior, as the NLB cluster is now responding to requests on the Virtual
Cluster address (i.e. - 10.10.10.169).
Written by Ryan Sokolowski (blogged with permission) - with minor changes and tweaks