Network load balancing with bridged NIC adapters

Question

I am having problems when trying to create a cluster by choosing the network bridge i created for my server. The cluster will return a host not found while configuring at the last step of a clustering on windows server 2008

Below is my setup

I have 2 Servers running windows server 2008 and each of the servers has 2 NIC that connects to 2 separate networks. Both of these network uses the same ip range and subnet. I created a bridge between the 2 NIC so from the server i will be able to view any of the PCs on any of the 2 network.

Because of the bridge so i have only 1 IP address for my server. Now i am trying to do network load balancing for both my servers so that both my servers which hosts a web server can share load and acts as a kind of redundancy.

I tried creating the Network load balancing via the Network load balancing manager. I connected to 1 of the host and it shows 3 network interface and only the bridge has an IP so i chose that and continued following the steps. I chose unicast (i also tried using multicast). when i reach the last step of the NLB configuration, i will get a message in the detail box - unable to reach host xxx.xxx.xxx.xxx (my bridged IP)

I am not sure if i am doing anything correct or wrong.

Answer 1

While not familiar with Windows NLB (other than fearing it from a network guy's perspective), what it sounds like you're doing is bridge looping your network. This could turn out quite bad.

Consider:

Server1---nic1---subnet1---nic1---Server2
       |--nic2---subnet2---nic2--|

This is a bridge loop and is bad. Normally, you'd be setting up a scenario where you will bury your network a traffic storm. An NLB expert may contradict me, and it's likely they will be right, as I'm not familiar enough with NLB functionally to be certain. However, simply bridging these connections is not a good idea, neither from a moving packets perspective, nor a broadcast domain one.

Answer 2

I am not sure of the cause of your issues, but having a computer/server connected to two seperate networks that both have the same IP range and subnet is going to cause problems.