27 research outputs found

    Pre-Congestion Notification Encoding Comparison

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    DiffServ mechanisms have been developed to support Quality of Service (QoS). However, the level of assurance that can be provided with DiffServ without substantial over-provisioning is limited. Pre-Congestion Notification (PCN) investigates the use of per-flow admission control to provide the required service guarantees for the admitted traffic. While admission control will protect the QoS under\ud normal operating conditions, an additional flow termination mechanism is necessary in the times of heavy congestion (e.g. caused by route changes due to link or node failure).\ud Encoding and their transport are required to carry the congestion and pre-congestion information from the congestion and pre-congestion points to the decision points. This document provides a survey of\ud several encoding methods, using comparisons amongst them as a way to explain their strengths and weaknesses.\u

    Methods for evaluation packet delay distribution of ows using Expedited Forwarding PHB, Journal of Telecommunications and Information Technology, 2004, nr 2

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    The paper regards problem of providing statistical performance guarantees for real-time flows using Expedited Forwarding Per Hop Behavior (EF PHB) in IP Differentiated Services networks. Statistical approach to EF flows performance guarantees, based on calculation of probability that end-to-end packet delay is larger than certain value, allows larger network utilization than previously proposed deterministic approach. In the paper different methods of packet delay distribution evaluation are presented and compared. Considered cases comprise evaluation of delay distribution models for the core network and evaluation of end-to-end packet delay in the network consisted of edge node and chain of core nodes. Results obtained with aid of analytical models are compared with simulation results

    Pre-Congestion Notification Encoding Comparison

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    EMERGE - ESnet/MREN Regional Science Grid Experimental NGI Testbed

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    QoS in Node-disjoint Routing for Ad Hoc Networks

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    PhDA mobile ad hoc network (MANET) is a collection of mobile nodes that can communicate with each other without using any fixed infrastructure. It is necessary for MANETs to have efficient routing protocol and quality of service (QoS) mechanism to support multimedia applications such as video and voice. Node-Disjoint Multipath Routing Protocol (NDMR) is a practical protocol in MANETs: it reduces routing overhead dramatically and achieves multiple node-disjoint routing paths. Because QoS support in MANETs is important as best-effort routing is not efficient for supporting multimedia applications, this thesis presents a novel approach to provide that support. In this thesis NDMR is enhanced to provide a QoS enabled NDMR that decreases the transmission delay between source and destination nodes. A multi-rate mechanism is also implemented in the new protocol so that the NDMR QoS can minimise the overall delays. It is shown that these approaches lead to significant performance gains. A modification to NDMR is also proposed to overcome some of the limitations of the original

    Journal of Telecommunications and Information Technology, 2004, nr 2

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    Provision of Quality of Service in IP-based Mobile Access Networks

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    Management qualitätsbasierter Gruppenkommunikation im Internet

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    Zugangs- und Nutzungskontrolle bei Unicast bedarf allein der Überwachung am Netzeingang. Diese Arbeit entwirft das Verfahren DSMC (Diffserv Multicast), das die für Multicast zusätzlich benötigte Kontrolle im Netzinneren ergänzt. Es erweitert die Paketweiterleitung (MFC) der Router nur gering und ohne Eingriff in das Multicastrouting, unterstützt so alle Multicastroutingprotokolle des Internets und bietet eine skalierbare Signalisierung zur Steuerung durch zentrales Dienstgütemanagement
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