I. Introduction
Packet networks have dramatically gained in importance and popularity in recent years, especially due to the widespread use of the Internet, which is a heterogeneous collection of networks. Currently, the Internet does not provide quality-of-service (QoS) guarantees, and transmission of audio and video places considerable strain on the resources of any connection due to the amount of data involved. In addition, transmission of audio and video poses a major challenge as their real-time nature and interactivity requirements typically preclude the use of reliable handshake-based protocols. The delays added by relying on retransmission mechanisms for packet loss recovery are generally not compatible with interactive or broadcast audio and video applications.