The following is an example of FF TMG 2010 NLB Configuration.
To configure network load balancing among FF TMG 2010 enterprise array members, Open FF TMG enterprise Management server console, Click on the Networking Node>Select preferred networks. For this article, I have chosen internal networks for load balancing.
Click on Enable Network Load Balancing Integration, you will be presented with NLB Integration Wizard, Click Next.
Select Internal>Click Configure NLB Settings
Type Primary virtual IP (VIP), Select Unicast, Click OK. note that VIP will be similar IP range of internal networks of both TMG servers. VIP will be registered as a DNS record in DNS server once you click finish.
click Finish. Click OK.
Apply Changes. Click Ok.
To Change or add additional VIP, Click on Networking node>Right Click on Internal Network>Click Property>Click NLB Tab
Change FF TMG Client configuration to new VIP. Client proxy address will be new VIP.
Now you have finished configuring NLB. To test NLB, open internet explorer, add VIP as new proxy address and browse bing.com.
To test that you are able to browse internet using VIP proxy address if one NLB node fails, reboot one TMG server while you keep surfing internet on a client. you will experience slow browsing though depending on your load. you will see following error in TMG EMS but once all array members are up and running it will sync itself.
Important! you can centrally manage up to 15 EMS x 200 arrays per EMS x 50 TMG servers per array that is in total 150,000 TMG servers.