Implementation of a Parallel Transport Subsystem on a Multiprocessor Architecture

Requirements of emerging applications together with rapid changes in networking technology towards gigabit speeds require new adequate transport systems. Integrated designs of transport services, protocol architecture, and implementation platforms are needed for the requirements of forthcoming applications in high-speed network environments. The transport subsystem PATROCLOS (parallel transport subsystem for cell based high speed networks) is designed with special emphasis on a high degree of inherent parallelism to allow efficient implementations on multiprocessor architectures combined with specialised hardware for very time critical functions. The paper presents transport system design guidelines based on experiences gained with parallel implementations of transport and network layer protocols on transputer networks, an implementation architecture for PATROCLOS based on transputer networks and results of a performance evaluation, which indicate promising throughput values. tions on hybrid multiprocessor platforms. In addition, several characteristics of emerging cell based networks such as ATM and DQDB influence the protocol design for the transport system [5]. A number of protocol mechanisms (e.g., connection management, error control, flow control) need to be changed in order to take advantage of the provided network bandwidth [6]. Moreover, since a large amount of data may be travelling between communicating end systems, it is impractical to maintain a consistent view of the state in both systems. The exchange of connection state information piggy-backed in user data can not be recommended for high performance communications. Mechanisms based on exchanges after dedicated requests (e.g., XTP [7]) or periodic exchanges (e.g., SNR [2]) seem to be more suitable. The parallel transport subsystem PATROCLOS presented in this paper attempts to overcome the performance limitations by the integration of protocol and implementation issues and by providing the required functionalities between the media access layer interface of cell-based networks and the transport layer interface in a single, modular designed protocol component.