Traffic regulation in cross-path ATM packet switch for end-to-end quality of service guarantees

Previously, a quasi-static routing scheme called path switching was proposed for large-scale ATM packet switches, and a Clos network implementing this routing scheme is called a cross-path switch. In principle, a cross-path switch supports both multicast and multirate traffic and now we add the capacity of supporting per-connection quality of service (QoS) guarantees. In this paper we develop a model to guarantee per-connection QoS in cross-path switches. By characterizing the output traffic, we observe that due to the quasi-static nature of path switching, traffic always becomes more bursty after passing through the cross-path switch. This traffic distortion would greatly degrade performance guarantees at the successive switches along the path. In order to achieve better end-to-end performance guarantees, we propose two regulation schemes for the cross-path switch to reduce distortion. For comparison, their delay bounds are derived. Our results show that with the designed control strategies, both schemes can effectively preserve or even reduce the burstiness of individual traffic streams across the switch with optimal performance guarantees.