967 research outputs found

    On-board B-ISDN fast packet switching architectures. Phase 2: Development. Proof-of-concept architecture definition report

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    For the next-generation packet switched communications satellite system with onboard processing and spot-beam operation, a reliable onboard fast packet switch is essential to route packets from different uplink beams to different downlink beams. The rapid emergence of point-to-point services such as video distribution, and the large demand for video conference, distributed data processing, and network management makes the multicast function essential to a fast packet switch (FPS). The satellite's inherent broadcast features gives the satellite network an advantage over the terrestrial network in providing multicast services. This report evaluates alternate multicast FPS architectures for onboard baseband switching applications and selects a candidate for subsequent breadboard development. Architecture evaluation and selection will be based on the study performed in phase 1, 'Onboard B-ISDN Fast Packet Switching Architectures', and other switch architectures which have become commercially available as large scale integration (LSI) devices

    Product-form solutions for integrated services packet networks and cloud computing systems

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    We iteratively derive the product-form solutions of stationary distributions of priority multiclass queueing networks with multi-sever stations. The networks are Markovian with exponential interarrival and service time distributions. These solutions can be used to conduct performance analysis or as comparison criteria for approximation and simulation studies of large scale networks with multi-processor shared-memory switches and cloud computing systems with parallel-server stations. Numerical comparisons with existing Brownian approximating model are provided to indicate the effectiveness of our algorithm.Comment: 26 pages, 3 figures, short conference version is reported at MICAI 200

    On the Stability of Isolated and Interconnected Input-Queued Switches under Multiclass Traffic

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    In this correspondence, we discuss the stability of scheduling algorithms for input-queueing (IQ) and combined input/output queueing (CIOQ) packet switches. First, we show that a wide class of IQ schedulers operating on multiple traffic classes can achieve 100 % throughput. Then, we address the problem of the maximum throughput achievable in a network of interconnected IQ switches and CIOQ switches loaded by multiclass traffic, and we devise some simple scheduling policies that guarantee 100 % throughput. Both the Lyapunov function methodology and the fluid modeling approach are used to obtain our results

    Priority Control in ATM Network for Multimedia Services

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    The communication network of the near future is going to be based on Asynchronous Transfer Mode (ATM) which has widely been accepted by equipment vendors and service providers. Statistical multiplexing technique, high transmission speed and multimedia services render traditional approaches to network protocol and control ineffective. The ATM technology is tailored to support data, voice and video traffic using a common 53 byte fixed length cell based format with connection oriented routing. Traffic sources in A TM network such as coded video and bulk data transfer are bursty. These sources generate cells at a near-peak rate during their active period and generate few cells during relatively long inactive period. Severe network congestion might occur as a consequence of this dynamic nature of bursty traffic. Even though Call Admission Control (CAC) is appropriately carried out for deciding acceptance of a new call, Quality of Service (QOS) may be beyond the requirement limits as bursty traffic are piled up. So, priority control, in which traffic stream are classified into several classes according to their QOS requirements and transferred according to their priorities, becomes an important research issue in ATM network. There are basically two kinds of priority management schemes: time priority scheme that gives higher priority to services requiring short delay time and the space priority scheme that gives high priority cells requiring small cell loss ratio. The possible drawbacks of these time and space priority schemes are the processing overhead required for monitoring cells for priority change, especially in the case of time priority schemes. Also, each arriving cell needs to be time stamped. The drawback of the space priority scheme lies in the fact that buffer management complexity increases when the buffer size becomes large because cell sequence preservation requires a more complicated buffer management logic. In this thesis, a Mixed Priority Queueing or MPQ scheme is proposed which includes three distinct strategies for priority control method -- buffer partitioning, allocation of cells into the buffer and service discipline. The MPQ scheme is, by nature, a non-fixed priority method in which delay times and loss probabilities of each service class are taken into account and both delay times and loss probabilities can be controlled with less dependency compared with the fixed priority method, where priority grant rule is fixed according to the service class, and the priority is always given to the highest class cell among cells existing in the buffer. The proposed priority control is executed independently at each switching node as a local buffer management. Buffer partitioning is applied to overcome the weakness of the single buffer

    Scheduling algorithms for high-speed switches

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    The virtual output queued (VOQ) switching architecture was adopted for high speed switch implementation owing to its scalability and high throughput. An ideal VOQ algorithm should provide Quality of Service (QoS) with low complexity. However, none of the existing algorithms can meet these requirements. Several algorithms for VOQ switches are introduced in this dissertation in order to improve upon existing algorithms in terms of implementation or QoS features. Initially, the earliest due date first matching (EDDFM) algorithm, which is stable for both uniform and non-uniform traffic patterns, is proposed. EDDFM has lower probability of cell overdue than other existing maximum weight matching algorithms. Then, the shadow departure time algorithm (SDTA) and iterative SDTA (ISDTA) are introduced. The QoS features of SDTA and ISDTA are better than other existing algorithms with the same computational complexity. Simulations show that the performance of a VOQ switch using ISDTA with a speedup of 1.5 is similar to that of an output queued (OQ) switch in terms of cell delay and throughput. Later, the enhanced Birkhoff-von Neumann decomposition (EBVND) algorithm based on the Birkhoff-von Neumann decomposition (BVND) algorithm, which can provide rate and cell delay guarantees, is introduced. Theoretical analysis shows that the performance of EBVND is better than BVND in terms of throughput and cell delay. Finally, the maximum credit first (MCF), the Enhanced MCF (EMCF), and the iterative MCF (IMCF) algorithms are presented. These new algorithms have the similar performance as BNVD, yet are easier to implement in practice
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