Network Address Translation

The Access Edge and Web Conferencing Edge services have always worked fine with NAT, but when Office Communications Server 2007 was released, it was a requirement to have a publicly routable address space for the external A/V Edge Server interface. In Office Communications Server 2007 R2, support was added for using NAT on the A/V Edge Server interface, but only if a single Edge Server existed in that location. If Edge Server redundancy was required, each A/V Edge interface required a publicly routable address on the adapter.

Lync Server 2010 introduced the capability to use NAT for all three services, including the A/V Edge interface for pools with multiple Edge Servers. Lync Server 2013 continues to support this feature by allowing administrators to specify the public IP address associated with each private A/V Edge address in Topology Builder so that the server will still hand out the correct public IP to clients.

There are some caveats to using NAT, particularly around firewall rules and load balancing.