If you configured a 2007 R2 Edge topology, you will need to update the Edge (Media) topology for your Lync Server 2010 Front ...

If you configured a 2007 R2 Edge topology, you will need to update the Edge (Media) topology for your Lync Server 2010 Front End pools, Mediation Server, and Survivable Branch Appliances. If you have configured a 2007 R2 or 2007 Edge topology for federation and public IM connectivity, you must update your site federation route to use this Edge topology.