35,129 research outputs found
SCTP - Evaluating, Improving and Extending the Protocol for Broader Deployment
Zugriff auf den Volltext ist gesperrt, neue Version unter DuEPublico-ID 35000
The Stream Control Transmission Protocol (SCTP), originally designed for
the transport of signaling messages over IP based telephony signaling networks,
is a general transport protocol with features suitable for a variety
of applications that can benefit from multihoming, multiple streams, or one
of SCTP’s numerous extensions. To date, SCTP has found its way into all
kernel implementations of UNIX derivatives and a Windows prototype, but
there are still flaws, which have to be identified and corrected.
In this thesis, first, a suite of tools consisting of an SCTP simulation and
testing environment is provided to lay the groundwork for further studies.
Starting from comparing and analyzing kernel implementations, several aspects
of the protocol that lead to undesirable behavior are examined. Congestion
and flow control that are adopted from the Transmission Control
Protocol (TCP), although using the same mechanisms, need a special treatment
because of SCTP’s message orientation. The analysis of the SCTP
specific characteristics with the help of the simulation will finally result in
solutions that lead to a better performance.
The deployment of SCTP will be another concern that can be improved
by introducing a specific Network Address Translation (NAT) for SCTP.Zugriff auf den Volltext ist gesperrt, neue Version unter DuEPublico-ID 35000
Das Stream Control Transmission Protocol (SCTP) wurde ursprünglich für
den Transport von Signalisierungsnachrichten über IP basierte Netze konzipiert.
Inzwischen hat es sich jedoch zu einem allgemeinen Transportprotokoll
entwickelt, das einzigartige Eigenschaften besitzt. Daher ist es
besonders für Anwendungen interessant, die von mehreren Netzwerkadressen
pro Verbindung (Multihoming), mehreren unabhängigen Nachrichtenströmen
oder einer der zahlreichen Protokollerweiterungen profitieren können. Mittlerweile
hat SCTP in die Betriebssystemkerne aller UNIX-Derivate und eines
Windows Prototyps Einzug gehalten, aber es gibt noch Mängel, deren Ursachen
es zu entdecken und zu korrigieren gilt.
In dieser Dissertation wird zunächst eine Reihe von Werkzeugen bereitgestellt,
um die Grundlage für weitere Untersuchungen zu schaffen. Ausgehend
von der Analyse und dem Vergleich von Implementierungen im Systemkern
verschiedener Betriebssysteme werden einige Aspekte des Protokolls
untersucht, die zu unerwünschtem Verhalten führen. Die Prinzipien der
Überlast- und Flusskontrolle wurden vom stream-orientierten Transmission
Control Protocol (TCP) übernommen und benutzen daher dieselben Mechanismen.
SCTP als nachrichtenorientiertes Protokoll benötigt jedoch eine
diesem Unterschied Rechnung tragende Implementierung der Algorithmen.
Die Analyse von SCTP-spezifischen Charakteristika mithilfe der Simulation
wird schließlich zu Lösungen führen und zu einer Verbesserung des Durchsatzes.
Ein weiteres Anliegen dieser Arbeit ist die Verbreitung von SCTP. Sie
kann durch die Einführung einer SCTP-spezifischen Methode zur Umsetzung
von Netzwerkadressen (Network Address Translation (NAT)) verbessert werden
A WebRTC Video Chat Implementation Within the Yioop Search Engine
Web real-time communication (abbreviated as WebRTC) is one of the latest Web application technologies that allows voice, video, and data to work collectively in a browser without a need for third-party plugins or proprietary software installation. When two browsers from different locations communicate with each other, they must know how to locate each other,
bypass security and firewall protections, and transmit all multimedia communications in real time. This project not only illustrates how WebRTC technology works but also walks through a real example of video chat-style application. The application communicates between two remote users using WebSocket and the data encryption algorithm specified in WebRTC technology. This project concludes with a description of the WebRTC video chat application’s implementation in Yioop.com, a PHP-based internet search engine
The Xpress Transfer Protocol (XTP): A tutorial (expanded version)
The Xpress Transfer Protocol (XTP) is a reliable, real-time, light weight transfer layer protocol. Current transport layer protocols such as DoD's Transmission Control Protocol (TCP) and ISO's Transport Protocol (TP) were not designed for the next generation of high speed, interconnected reliable networks such as fiber distributed data interface (FDDI) and the gigabit/second wide area networks. Unlike all previous transport layer protocols, XTP is being designed to be implemented in hardware as a VLSI chip set. By streamlining the protocol, combining the transport and network layers and utilizing the increased speed and parallelization possible with a VLSI implementation, XTP will be able to provide the end-to-end data transmission rates demanded in high speed networks without compromising reliability and functionality. This paper describes the operation of the XTP protocol and in particular, its error, flow and rate control; inter-networking addressing mechanisms; and multicast support features, as defined in the XTP Protocol Definition Revision 3.4
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Computing infrastructure issues in distributed communications systems : a survey of operating system transport system architectures
The performance of distributed applications (such as file transfer, remote login, tele-conferencing, full-motion video, and scientific visualization) is influenced by several factors that interact in complex ways. In particular, application performance is significantly affected both by communication infrastructure factors and computing infrastructure factors. Several communication infrastructure factors include channel speed, bit-error rate, and congestion at intermediate switching nodes. Computing infrastructure factors include (among other things) both protocol processing activities (such as connection management, flow control, error detection, and retransmission) and general operating system factors (such as memory latency, CPU speed, interrupt and context switching overhead, process architecture, and message buffering). Due to a several orders of magnitude increase in network channel speed and an increase in application diversity, performance bottlenecks are shifting from the network factors to the transport system factors.This paper defines an abstraction called an "Operating System Transport System Architecture" (OSTSA) that is used to classify the major components and services in the computing infrastructure. End-to-end network protocols such as TCP, TP4, VMTP, XTP, and Delta-t typically run on general-purpose computers, where they utilize various operating system resources such as processors, virtual memory, and network controllers. The OSTSA provides services that integrate these resources to support distributed applications running on local and wide area networks.A taxonomy is presented to evaluate OSTSAs in terms of their support for protocol processing activities. We use this taxonomy to compare and contrast five general-purpose commercial and experimental operating systems including System V UNIX, BSD UNIX, the x-kernel, Choices, and Xinu
The Xpress Transfer Protocol (XTP): A tutorial (short version)
The Xpress Transfer Protocol (XTP) is a reliable, light weight transfer layer protocol. Current transport layer protocols such as DoD's Transmission Control Protocol (TCP) and ISO's Transport Protocol (TP) were not designed for the next generation of high speed, interconnected reliable networks such as fiber distributed data interface (FDDI) and the gigabit/second wide area networks. Unlike all previous transport layer protocols, XTP is being designed to be implemented in hardware as a VLSI chip set. By streamlining the protocol, combining the transport and network layers, and utilizing the increased speed and parallelization possible with a VLSI implementation, XTP will be able to provide the end-to-end data transmission rates demanded in the high speed networks without compromising reliability and functionality. This tutorial briefly describes the operation of the XTP protocol and in particular, its error, flow and rate control; inter-networking addressing mechanisms; and multicast support features, as defined in the XTP Protocol Definition Revision 3.4
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