The hardware load balancer requirements for Director and Front End Pool Web Services are listed below:

  • For internal Web Service Virtual IPs (VIPs), set source IP address persistence (internal port 80, 443) on the hardware load balancer. For Lync Server 15, source IP address persistence means that multiple connections coming from a single IP address are always sent to one server to maintain the session state.
  • Set the TCP idle timeout to 1800 seconds.
  • On the firewall between the reverse proxy and the next hop pool’s hardware load balancer, create a rule to allow HTTPS traffic on port 4443 from the Reverse Proxy to the hardware load balancer. The hardware load balancer must be configured to listen on ports 80, 443 and 4443.