A backend server farm is a group of homogeneous backend servers. A client making a request through the Relay Server farm must specify the backend server farm it is targeting.

The load balancer directs requests from the mobile devices to a Relay Server running in the Relay Server farm. The load balancer is not required if there is only one Relay Server.

The Relay Server Outbound Enabler runs on the same computer as the backend server. Its primary function is to initiate an outbound connection to all Relay Servers in the Relay Server farm on behalf of the backend server. There is usually only one, but there may be several, Relay Server Outbound Enablers (RSOEs) per backend server.

• See Outbound Enabler.