Microsoft Terminology

Load balancers can be configured to support Network Address Translation (NAT) using one of the following modes:

  • Full-NAT (SNAT) mode (also known as proxy, secure NAT, source NAT, or SNAT mode): In full-NAT mode, both the source and IP destinations are changed as packets pass through the load balancer.
  • Half-NAT (DNAT) mode (also known as transparency, destination NAT, DNAT mode or Load Balancers Default Gateway LBDG): In half-NAT mode, the destination IP address is changed as packets pass through the load balancer, but the source IP address remains intact.
Note: Load balancing using Direct Server Return configuration is not supported.

The following table describes the supported configurations for full-NAT and half-NAT modes.

Load-Balanced Pools Supported NAT Modes Notes
Enterprise pools and Communicator Web Access

Full-NAT (SNAT)

Half-NAT is not supported for load balancing of internal pools because inter-server communications within an internal pool fail when servers in the pool try to connect to their own VIP
Edge pools

Full-NAT (SNAT)

and

Half-NAT (DNAT)

The VIP for the external interface of Edge Servers should be set to half-NAT or full-NAT only for traffic to the edge (for each VIP that is used for Edge Servers and HTTP). Also, NAT is not supported for the IP address of the external interface of the A/V Edge Server of an Edge Server, so the IP address of the external interface of the A/V Edge service on each Edge Server must be publicly routable (no NAT).