A Network Level Channel Abstraction for Multimedia Communication in Real-Time Networks

The main challenge in the design of an efficient distributed multimedia system is the integration and support of a wide variety of real-time applications. These applications require considerably different qualities of service, in terms of expected throughput, delay, acceptable level of errors, specific degree of packet loss, and ability to dynamically adjust resource requirements. The design of communication protocols to support guaranteed real-time communication for distributed multimedia systems is the focus of this paper. We propose a network level abstraction called ϕ -channel to support the requirements of real-time applications. A ϕ -channel represents a fractional, simplex, end-to-end communication channel between a source and a destination. The channel is characterized by a set of specific performance parameters associated with its traffic. The required performance characteristics of a ϕ-channel are specified in terms of the packet maximum end-to-end delay and the maximum number of packets that can be sent over that delay. The primary attribute supported by the ϕ-channel is the on-time reliability. Based on the specified parameters, the underlying delivery system verifies the feasibility of supporting such a channel. The performance of an accepted ϕ-channel are guaranteed under any conditions, baring hardware failures. The basic scheme that our model uses to verify the feasibility of accepting a ϕ-channel and the run-time support used to guarantee its performance are described. The results of a simulation experiment implementing the basic functionalities of the proposed scheme are also presented.