Topic Last Modified: 2011-03-23

When you choose a topology, you can use one the following supported topology options:

The following table summarizes the functionality available with the three supported Microsoft Lync Server 2010 communications software topologies. The column headings indicate the functionality available for a given Edge configuration option. Using the Scaled Edge (DNS load balanced) option as an example, you can see that it supports high availability, requires network address translation of Edge external interfaces, , reduces cost because a hardware load balancer is not required and does not support failover for Exchange Unified Messaging (UM), public instant messaging (IM) connectivity, and federation with servers running Office Communications Server.

Summary of Edge Server Topology Options

Topology High availability NAT required Additional external DNS A record required for each Edge Server in the Edge pool Failover*

Single Edge

No

Yes

No

No

Scaled Edge (DNS load balanced)

Yes

Yes

Yes

No

Scaled Edge (hardware load balanced)

Yes

No

No (only one per VIP)

Yes

* Failover for Exchange UM (remote user), public instant messaging (IM) connectivity, and federation with servers running Office Communications Server.

Note:
The NAT required and Additional external DNS A record required for each Edge Server in the Edge pool columns pertain only to the Edge external interfaces. A Yes in the NAT required column means that the associated Edge Server topology supports the use of NAT on the Edge external interfaces. If you decide to use NAT, you must use it on all three external interfaces. A Yes in the Additional external DNS A record required for each Edge Server in the Edge pool column means that you need a DNS A record (and associated public IP address) in your external DNS for each Edge Server added to your Edge pool.

The primary decision points for topology selection are high availability and load balancing. The requirement for high availability can influence the load balancing decision.