FPGA Design And Implementation Of An ATM Switch With Large Capacity And AAL5Function

The ATM technology with superior comprehensive performance had widely application in communication networks. Today ATM technology is still used in space communications, wireless networks and other special areas. Relying on the project named a Prototype ATM Switch with lOGbps large capacity, this dissertation focuses on the design scheme of an ATM Switch with AAL5function and the FPGA implementation of receiving direction function of AAL5protocol. Compared with existing implementations, this scheme based on FPGA has the higher data processing speed, and can accomplish stronger portability and scalability.Based on the brief discussion of ATM switching theory, the switching fabric and AAL5principle, this dissertation studies a FPGA implementation scheme of the large capacity ATM switch with AAL5, describing the main module’s functions of cell preprocessing, cell switching, AAL5and others. The study emphasis is on the design and implementation of the FPGA modules in AAL5receiving direction, including modules of the Internal channel Number (ICN) mapping, cell classification processing, receiver width transformation, buffering write control, cell reassembling, CRC processing and PoS Level3interface control. This dissertation performed the function analysis, VHDL programming, and simulation validation of each module mentioned above, as well as the simulation validation of the whole AAL5receiving dirction processing. Another major work studies the function enhancements and improvements of the switching module. The testing process, method, results, and the problems encountered in and their solutions in the debugging of the prototype developed are investigated. Test results show that the prototype meets the design requirements. The efforts made in this dissertation laid a good technical foundation for developing a FPGA-implemented large capacity ATM switch with AAL5function.