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An ATM switching system architecture is presented which employs distributed control to cope with diversified requirements. ATM switching system is expected to efficiently and flexibly handle multimedia traffic, therefore traffic control architecture is one of the most crucial issues for ATM switching systems. The requirements, architectural concept and construction scheme of two important technologies, self-routing switches and quality control of statistical switching, are discussed. A switch fabric, which provides a unified inter-module inter face, switches and distributes cells between modules. It gives very stable switching performance under an arbitrary flow environment without centralized resource management. A three-layerd traffic control model is also presented which consists of cell transfer level, call control level and network control level. Control functions of each level and the interfaces among them are considered, then cell transfer level control schemes and their performances are discussed, including marking scheme for policing control and the effect of burstiness. Laboratory experiment system is designed and implemented to confirm the feasibility of the ATM switching system architecture concept. The system employs a VLSI memory switch with dynamic link speed control as an element of the self-routing switch fabric, achieving the capacity of 256 I55Mb/s lines. It also realizes efficient statistical switching functions such as policing control, multiplexing and quality control for multiple transport quality classes. |
