I don't know anything about Pound, but I've done this with HAProxy and the theory I'm guessing is the same:
- Have two servers setup to serve the same website, as identical as possible (identical in terms of setup, not necessarily hardware)
- Set up a third server infront of these two servers, which will be your load balancer, and also your public facing interface to the world
- Configure the load balancer to distribute the incoming requests over the two servers. If one server can handle 10x the number of requests as the 2nd server, you can set up say a 10:1 balance in any decent load balancer.
So yes, you'll need a third server, however - there's a few things that might make your life better:
- The load balancer doesn't need to be physical - it can be a virtual machine. In fact if you make it a virtual machine that makes it a lot more flexible as you can move it around without anyone noticing
- The load balancer doesn't need to be a fancy pants machine if your request volume is low. I've had great success on a Pentium 4 box with HAProxy and a gig of ram (serving around 60,000 requests a day).
Load balancing and .NET websites can have some fun when it comes to session states and locally stored variables, but load balancers generally have settings that allow you to stick users to one web server, so that all future requests go to the same server for read the same data. If you don't have this issue then feel free to use round robin or some other method.