I am using Microsoft Dynamics NAV 2009's Role-Tailored Client (RTC), which utilizes a 3-tier architecture. The middle tier, which Microsoft calls the service tier, is a non-cluster-aware application that runs as a Windows service. I've identified through another question that I should pursue running a clustered hypervisor with a virtual machine running the NAV Service Tier.
Unfortunately, the NAV Service Tier has a recommended maximum user capacity of 50-60 users. With over 100 concurrent users, I will need some mechanism to "load balance" all of the sessions without having to visit each user's workstation and "hard-code" it to a specific server. Sessions will need to be sticky in that every request after the initial request will need to be routed to the same server.
How can I load balance a Windows service which is not IIS-based and meets the requirements I've outlined?
Best Answer
I think Windows Network Load Balancing (NLB) will work for you - it uses multicast to allow multiple servers to be accessed by the same IP address. The servers decide between themselves which one will handle a request. It can be configured to be sticky (session affinity). Be aware however, that it only offers redundancy in terms of whether a server is up or down - it can't decide which server in the cluster is under less load.
Most documentation out there will discuss IIS and NLB, but it works for RDP and other applications. I have had some issues using this over Dell PowerConnect switches in a high load scenario, and would be inclined to go for a more heavyweight load balancing solution, but I think for your purposes it is the best place to start. It's free with Windows Server.