Consider the following scenario:
You enable the Call Admission Control (CAC) feature in a Microsoft Lync Server 2010 environment.
You set the session limit of the bandwidth to the 100kbs value.
A bandwidth update is sent to the Policy Decision Point (PDP) server during the operation of the Lync Server 2010 environment.
The bandwidth that the update requests is more than the session limit.
In this scenario, PDP allows the request.
To resolve this issue, install the following cumulative update:
2502809 Description of the cumulative update for Lync Server 2010, Core Components: November 2011