 We have seen all the functional entities in RSEF which are going to be working together to bring about quality of service based service provisioning to the user for certain flow, a multimedia flow or simply a voice call. So we are going to look at now how exactly this QoS is translated from policy decision the path from the SCF to PD to PE to TC traffic control resource and then traffic control enforcement. So we will start with this understanding of how this translational binding takes place. As we already know that the enforcement actually means apply the requirements coming from above after having understood them in terms of the parameters that the network understands. So this is known as binding. Performing binding of a request from a user flow actually means to take very important and intelligent decision that does not choke the network, that does not disrupt existing ongoing connections and that yet meets the requirements coming in this particular request. So here the concept of token is introduced. This is known as the authorization token. Authorization token actually means it's a go ahead coming from the processing of all these functional entities. So the authorization tokens are basically the permission grants which are logged for subsequent billing and charging at a later stage. So the policy decision functional entity generates the tokens when it gets a request from the SCF above and this token takes into account certain identifiers which are going to determine the requirement, the network elements which are going to be used and the QS parameters which would be translated. So the token actually is the domain in which this enforcement has to be implemented. Then the resource for which this binding is going to take place. Now the resource actually is going to be utilized for a certain QS requirement for some media flow. It means the resource is going to become more and more busy. It means the resource control session ID is going to determine for how long a resource is going to stay tied up for a certain flow and till that time the resource is not relieved or it is not spared. Additional requests for the media flow QS requirements can be denied or delayed.