ISA Server and SharePoint get along very well. E.g. the Alternate Access Mappings concept in SharePoint 2007 ties in well with the link mapping capabilities of ISA Server 2006.

 

Then again, Hyper-V is a perfect platform to run a SharePoint server farm. So I was wondering when we first started deploying SharePoint on Hyper-V at the end of 2007, whether we could also virtualize the load-balanced ISA servers with it. That would be so much easier to administrate altogether!

 

I found this article that confirmed my gut-level feeling: Understanding Networking with Hyper-V. This clearly looked like the Host server could be entirely disconnected from the network, and that all traffic would have to go through the virtual ISA servers, making this a pretty secure virtual solution!

 

Well, we weren't quite there yet! After a successful installation of the ISA servers we later experienced quite some problems with the load-balancing and, through trial and error, solved the problem by using Legacy network adapters for the ISA servers.

 

A couple of weeks later Ben Armstrong hinted in the right direction, stating that Offloading was the cause of the problem. Mark Wilson summed it up quite well, again a few weeks later, and in June, Microsoft finally released some definitive information about the issue.

 

Long story short: ISA Server 2006 works great on Hyper-V. We are using it both for load-balancing ISA servers and SharePoint Web Frontends and it hasn't let us down once in all these months.

 

Of course, one can still add more hardware-based firewalls as a first-line defence for additional security. However, I love the additional functionality the ISA Server offers, on top of the security it provides.