Packet Dispatching Algorithms with the Static Connection Patterns Scheme for Three-Stage Buffered Clos-Network Switches

Rapid expansion of the Internet and increasing demand for multimedia services fosters an immediate need for the development of new high-capacity networks capable of supporting these growing bandwidth requirements. The development of broadband transport networks resulted in the need for next generation switches/routers with high-speed interfaces and large switching capacity. The main part of every switching node is a switching fabric, which provides a connecting path between input and output lines. For high-performance switches and routers the Clos-network is very attractive because of its modular architecture and scalability. In packet switching systems packet dispatching algorithms were adopted to avoid packet contention, which may occur while a packet is being routed in a switching fabric. Different dispatching schemes for the buffered Clos-network switches were proposed in many papers. Most of them consist of request, grant and accept phases, and cannot work in the real environment. In this paper the application of static connection patterns to packet dispatching algorithms for the three-stage buffered Clos-network switches is proposed. The performance of two such algorithms, called static desynchronization (SD) and maximal matching static desynchronization (MMSD), is evaluated and compared with results obtained for CRRD (concurrent round-robin dispatching) and CMSD (concurrent master-slave round-robin dispatching) schemes. We would like to show that it is possible to use a very simple packet dispatching scheme and obtain an acceptable performance for a wide range of traffic load per input port.