Providing per-session deterministic quality of service guarantees in cross-path packet switch

Recently, a quasi-static routing scheme called path switching was proposed for large-scale packet switch systems. The path-switched Clos network is called a cross-path switch. Cross-path switch is capable of supporting multirate and multicast traffic. In this paper, we develop a general framework for it to handle multimedia traffic. We obtain upper bounds on the delay and backlog at the cross-path switch on a per-session basis, wherein no packet lost or delay bound violation is allowed. Our results show that these bounds much depend on the way of token assignment at the central stage. To understand such dependence, we quantify the effect of the token assignment on the switch performance. From these results, we design an effective token assignment scheme to achieve better performance guarantees in the switch. We show that cross-path switch with such token assignments always provides near-optimal performance guarantees to each data session.