Admission control for hard real-time connections in ATM LANs

A connection admission control (CAC) algorithm must efficiently determine if a new connection can be admitted by verifying that its QoS requirements can be met without violating those of previously admitted connections. In hard real-time systems, the QoS requirements are specified in terms of end-to-end cell deadlines and no cell loss due to buffer overflow. To achieve these objectives a CAC algorithm must account for the traffic characteristics of connections. Furthermore, arbitrary topology of the network may lead to cyclic dependencies among various connections. An: efficient CAC algorithm is presented that addresses these issues. The algorithm uses a traffic descriptor called the 'maximum traffic rate function' to effectively compute bounds on end-to-end delays of connections and buffer requirements within the network. The work differs from most previous work in that it does not require traffic restoration inside the network.