Research On Extraction And Parsing Technologies Of ATM Cells Over SDH

This dissertation mainly investigates the ATM (Asynchronous Transfer Mode) cells over SDH (Synchronous Digital Hierarchy) net. And it uses two methods to implement ATM cells extraction and parsing over SDH net, then the performance of these two methods are compared .(1)According to the theoretic and engineering research of ATM over SDH, the dissertation presents ATM cells extraction algorithm which utilize HEC (Header Error Control) field. And the theory analyzes and simulation experiments are both carried out to inspect the algorithm performance.(2)The dissertation considers the ATM cell as the main research object. From the theoretic aspect, it parses the structure of ATM cell, including identifying and processing of ATM idle cell, ATM AALs(ATM Adaptation Layers) and user information extraction and recombination of AALs.( 3 ) To extract and parses ATM cells from SDH net, an FPGA(Filed Programmable Gate Array) based and a computer server based methods are carried out. For the former, the dissertation emphasizes the parallel algorithm for the CRC(Cyclic Redundancy Check). It also uses the"XOR plane"and the"AND plane"to realize the single bit error correction in CRC. For the latter, the software implementation of each function are described in detail.(4)The experiments about these two methods are provided and the test results of the experiments are analyzed.The theoretic analyzes and the experiment results proved that all the methods can operate effectively. The methods and technique make the ATM cells extraction and parsing from the SDH net possible and provide a new solution to the real time inspection of ATM information over SDH network.