Load balancing Lync 2013
Lync 2013 deployment consists of many different roles and services and is often quite complex compared to other Microsoft products, especially in conjunction with load balancing, since it uses many different protocols such as SIP and STUN and traditional protocols such as TCP and HTTPS.
Instead of covering the entire aspect of Lync deployment, I recommend you head on over to the deployment guide by Citrix available at https://www.citrix.com/content/dam/citrix/en_us/documents/products-solutions/microsoft-lync-2013-and-citrix-netscaler-deployment-guide.pdf.
