Sunshine: a high performance self-routing broadband packet switch architecture

The fiber based broadband network will offer services ranging from circuit emulations where extremely low cell loss rams are essential to high speed variable rate services which can tolerate a degree of cell loss but whose bandwidth requirements may be extremely bursty and unpredictable. This paper presents a high performance self-routing packet switch architecture called Sunshine, that is well suited for this wide range of potential services with their diverse performance objectives and traffic characteristics. Sunshine is based on Batcher/banyan networks and combines both internal and output queuing techniques within a single architecture. Access to the output queues is provided by parallel banyan routing networks which allow multiple cells to be delivered simultaneously to each destination. Excess cells, due to momentary output overloads, overflow into a shared recirculating queue where they are delayed and resubmited as dedicated switch inputs in the following packet slot. A priority structure ensures cefts access each queue based on priority allowing multiple grades of service to coexist within the switch. Results based on extensive simulations which modeled low speed services by a random arrival process, circuit emulations by a periodic arrival process, and high speed variable-rate services by a bursty process show that this architecture can achieve the extremely low cell loss rates necessary for circuit emulations, and is robust in a bursty environment.