My last post was going over issues I had setting up NLB clustered servers within an ESX or VMware environment. 

I thought I had it all figured out and then I had another issue.  Whenever I would restart one of the NLB servers, the other server and the host would be unreachable.  I had a –t ping up to all three IP’s to troubleshoot the issue.

I did some research and found that VMware recommends to use Multicast, and that if you used Unicast, there were a couple steps to follow.   (Wouldn’t you know I was using Unicast.  We are using Unicast because the network guys didn’t want to add ARP entries to our switches at the moment.)

Being that the vSwitch sends out RARP broadcasts to the switch, you need to set the “Notify Switches” to be NO.

Below are the steps.

Within your VI Client

• click on the Host name in the left column.
• click on Network under “Hardware” column.
• click on Properties on the right (next to remove)

This window will pop up.

Next …

• click on VM Network as shown above
• click “Edit” button

This window will pop up.

Next ….

• click on the NIC Teaming tab
• make sure the “Notify Switches dropdown is set to No
• click OK
• click close on the vSwitch properties window

Now you should have NO issues. 

Remember however that it is not recommended to use Unicast with ESX NLB clusters.  Unless you run into some reason not to, I would recommend using Multicast.

I hope this helps,

Michael Silva - MikePixel