Associate Mediation Server With Edge
To define a Mediation Server, specify settings that associate the Mediation Server with a Front End Server and with an Edge Server or pool. To associate the Mediation Server or pool with an Edge Server or Edge Server pool, do the following:
From the drop-down list, select the Edge pool or Edge Server to associate with the Mediation Server.
Click Next to continue.
If you have not yet defined an Edge Server or Edge Server pool in your deployment, the drop-down list will not contain entries. You can click Next to continue and edit the settings for the Mediation Server after you have added an Edge Server or pool to your deployment.
For additional details, see Deploy a Mediation Server in Topology Builder in Skype for Business Server 2015.