| Abstract |
Networking equipment that uses specialized hardware and embedded software to support high performance and quality of service (QoS) guarantees is an important and growing part of modern computer and communications technology. In this area, CSD-UofCrete and ICS-FORTH developed an ABR Server card as part of an Access Node Switch (ANS) that connects VDSL lines with the core ATM network, within the "Integrated Services Access Network (DIPOLO)" project. Like most ATM switch equipment, it uses specialised hardware peripheral devices for data plane and other time-critical operations, and software running on embedded processor(s) for non-time-critical control-plane operations. The contribution of this work is the design and implementation of the embedded software that implements the necessary tasks for the ABR Server card efficient operation. During this work we determined the hardware / software interfaces on the ABR Server card, and we implemented entities for the card management and communication with the Access Node Switch subsystems. Finally we implemented complex flow control operations characterized by real time limitations, aiming to offer higher level operations on the ABR Server Card, and evaluate its performance in correlation with the existing hardware resources. The software implementation meets the demands for flexibility, modularity, and scalability as well as the demands for efficient execution of the Access Node Switch tasks common to all subsystems. The ABR Server card software runs on a PowerPC Microprocessor (Motorola MPC860) and it work under the real time operating system VxWorks. The imlpementation code was written in C and consist of about 2800 lines. The debugging and measurements were performed on the real hardware and determined the software efficiency with regard to the above demands. Finally we measured the real time limitations due to the current card resources, and proposed the necessary modifications in order to increase their performance.
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Σχεδίαση και υλοποίηση λογισμικού χαμηλού επιπέδου για μεταγωγείς πακέτων υψηλών ταχυτήτων
