Investigation And Enhancment Of Asynchronous Transfer Mode Lans

Abstract

Since the early stages in the networking field, it has become very important to look for specific demands to make use of the modern technologies to satisfy needs of the employees and customers everywhere. So improvements proceeded to make use of these needs through the different generations. This project deals with the study of ATM technique as an improvement of the LAN generations. A comparison between it and the earlier network systems is held (low speed and high-speed service). Through this thesis a spread view of how the ATM works will be done learning the similarities and differences between ATM and other LAN technologies and how ATM is better than the others. The implementation work is covered in two parts the fist part is about using a special network simulator (The OPNET) to compare between the ATM and another technology the one used in this thesis is the FDDI of course this is not the only one that we can compare between it and the ATM but here in this work this technology is chosen. The comparison is held to compare between the two types through all the performance parameters but in this thesis only two parameters were held for the comparison which were the Mean application response time and the throughput. The results were found for different data transfer traffic light traffic, medium and high traffic. The ATM is found to be better than the other type when the traffic is high but in both low and medium traffic both technologies are still good. The second part of the implementation is studying the performance parameters of ATM LANs through using Sharp C program for the Header error check and the cell delay variation as two functions used for the performance measurements of ATM. The first program which is the HEC is used to detect and correct bit errors in the header not more than 8 bits any errors exceed that number the cell will be discarded. The second program which is the CDV is used to measure the delay between each message and the one after it. This delay varies each time with a specific tolerance that should not be exceeded. The user should give the initial values for the time the bit rate and the initial delay used in the network after that the program will start to calculate the delay each time a message is sent once the result is negative the cell will be discarded.