2. Elementary mechanisms

Before introducing the DiffServ service differentiation model, we describe the basic building blocks that can be used to construct such an architecture. The functions required to identify and characterize a flow are analyzed, as are the scheduling and congestion management mechanisms. Identifying and characterizing an IP flow are two functions that can be used to determine the flow's level of compliance with its service contract. On the other hand, the implementation of scheduling and queue management mechanisms can be used to satisfy the quality of service requirements that flows demand.