This document addresses the Stage-3 protocol between an Application Function (AF) and a Policy and Charging Rules Function (PCRF) in support of Service Based Bearer Control as described in [1]. The reference point between the AF and the PCRF is designated as the Tx reference point.

The Tx interface shall allow interactions between the AF and the PCRF for the purpose of local authorization of bearer level QoS resources based on the resources negotiated at the application layer and/or based on local policy. In addition, it supports the passing of information that may be used to establish flow based charging policy. Features of the Tx interface include the following:

1. Provision and removal of application level service and flow control information from the AF to the PCRF;

2. Request of application level service and flow control information from the PCRF to the AF;

3. Notification of bearer level events from the PCRF to the AF: and

4. Application control of the flow of packets on the bearer including the restriction of flow end-points (flow filtering).