Load Balancers with Live Communications Server 2005

Load balancing is based on various forms of network address translation (NAT) at layers 2 and 3 of the networking stack. You may also know that network topologies can be built using different NAT modes. You with me so far? OK then… load balancers can be connected in two LCS topologies, as an independent node on the network or as an intermediary device between the Front End servers and the rest of the network. The first type of connection I mentioned is referred to as a one-arm topology while the latter is referred to as a two-arm topology. The product group supports only Front End servers with a single network interface card with a single IP address. After you tell them this, here’s where customers go off and ask about configs that aren’t supported. Configurations involving two or more IP addresses and/or two or more network cards per Front End server could potentially work but they are not tested and not supported by Microsoft. No support cases, no code changes if issues are discovered.

More at http://blogs.technet.com/uc/archive/2007/03/30/load-balancers-with-live-communications-server-2005.aspx