As with Lync Server 2010, in Lync Server 2013 Enterprise pools, HTTP connections require a load balancer. This is typically a physical hardware load balancer, but a number of software load balancers, which can run virtualized, are supported.
At the time of writing, the following software load balancers are supported:
• A10 Networks 64-bit AX Series
• Citrix Systems Netscaler VPX
• KEMP LoadMaster VLM-100, VLM-1000
• Riverbed Technology Stingray Traffic Manager
Again, if these virtual appliances are to be collocated on a host with Lync Servers, their virtual hardware requirements should be considered. Be aware of any limitations in scalability of virtual load balancers in comparison to their hardware equivalents. ...