Routing of Voice and Data in Burst-Switched Networks

This paper addresses the static and centralized routing of voice and data traffic in burst switched networks. Since voice and data have markedly different traffic characteristics and performance requirements, their interaction in a unified switching and transmission structure greatly impacts their performance. Voice performance in a burst switched network is primarily measured by end-to-end freeze-out while figures-of-merit for data include end-to-end delay and stability that may be jeopardized due to the interaction with the higher priority voice traffic. We assume that our routing allows random bifurcation in voice and data paths and preemptive priorities for voice requirements. We first study routing of voice only, by using a multicommodity flow model with linearized link losses and average network loss as a minimization objective. Solving the resulting linear program, we observe that optimal routing strategies prefer to freeze a requirement at an early stage of its path rather than those requirements that are close to their destinations. We then study the voice/data interaction at the link level using an available fluid-flow model, and translate the combined link performance as a maximum flow constraint on a link. This constraint may have undesirable effects on the voice, such as introducing routes with flow absorbing loops, and unfair freezing of some requirements. We include all conflicting multiple objectives and constraints in a linear programming formulation and show how parameters can be tuned to produce desirable voice and data paths.