This paper analyzes the delay performance of 1-persistent CSMA/CD LANs with bus topology and a finite number of heterogeneous stations, each possessing an infinite buffer. The mean waiting time at each individual station is obtained under a light-traffic assumption that the channel is occupied only by successful transmission periods. It is shown that the stations near the heavy-traffic stations gain better performance among light stations and the extent to which the individual delays differ depends on the network configuration as well as the protocol parameters.

It is desirable to design an ATM switch that is nonblocking at the connection level by using simple connection admission control (CAC) schemes. To accomplish this goal, it is necessary to consider the relationships between CAC, cell-level quality-of-services (QOS), and the structure of multistage switches as well as switch modules. In this paper, we formulate a framework to design a multistage nonblocking ATM switch. We show that if a switch has the property of the Sufficiency of Knowledge of External Loads (SKEL), i.e., the property that its cell-level performance is robust to the distribution of incoming traffic among all inputs, then the switch is also nonblocking at the connection-level by using a simplified CAC that guarantees QOS of a connection by controlling the aggregate loads on outputs. Furthermore, we show that a Clos three-stage network using SKEL switch modules and Multipath Self-Routing (MPSR) also has the SKEL property and is a nonblocking switching network that needs CAC only at its outputs. We also demonstrate a design of multistage nonblocking ATM switches with Knockout switch modules.

This paper proposes a new multistage switch architecture for large-scale multicast ATM switching. The proposed architecture uses routing schemes both at the connection level and the cell level. This results in the reduction of the memory capacity required in the trunk number translators of the copy network modules. If Connection Splitting algorithm is used, a nonblocking switch can be constructed under the same nonblocking condition as that of point-to-point Clos network. It is shown that the memory requirements in the new switching network are less than the previous architectures.

This letter proposes a new routing strategy and a design of ATM switches. By partitioning internal links into subgroups based on the bandwidth of a connection request, an ATM switching network which is nonblocking in the wide sense at the connection level can be constructed without the need of internal-link speedup.