LoadMaster uses the concept of a Virtual Service to publish services to clients. Clients can be actual end user clients or other servers which require access to the servers published by the Virtual Service. Virtual Services within the LoadMaster give the LoadMaster knowledge about local routes between networks. Using the local route/short cut between these interfaces may not always be the desired behaviour and this can be true within the Lync context specifically when configuring a Multi headed deployment on a single pair of LoadMaster devices.

Enabling Use Default Route Only “forces” traffic to follow back from Virtual Services to Real Server when a Default Gateway is configured on the specific Virtual Service.

If the traffic flowing between Virtual Service and the Real Server is able to take the shorter route using the LoadMaster when symmetric network operation is not required then that is achieved by not having a Virtual Service Default Gateway. Note - If a Virtual Service does not have a default route then the LoadMaster default route will be used.

To apply the above set up to the Lync Single Pair deployment a typical packet flow is shown in the below diagram. Deployments are unique and alternative flows may be configured or required depending on the specific deployment.