39 research outputs found
Delay-centric handover in SCTP
The introduction of the Stream Control Transmission Protocol (SCTP) has opened the possibility of a mobile aware transport protocol. The multihoming feature of SCTP negates the need for a solution such as Mobile IP and, as SCTP is a transport layer protocol, it adds no complexity to the network. Utilizing the handover procedure of SCTP, the large bandwidth of WLAN can be exploited whilst in the coverage of a hotspot, and still retain the 3G connection for when the user roams out of the hotspot’s range. All this functionality is provided at the transport layer and is transparent to the end user, something that is still important in non-mobile-aware legacy applications.
However, there is one drawback to this scenario - the current handover scheme implemented in SCTP is failure-centric in nature. Handover is only performed in the presence of primary destination address failure. This dissertation proposes a new scheme for performing handover using SCTP. The handover scheme being proposed employs an aggressive polling of all destination addresses within an individual SCTP association in order to determine the round trip delay to each of these addresses. It then performs handover based on these measured path delays. This delay-centric approach does not incur the penalty associated with the current failover-based scheme, namely a number of timeouts before handover is performed. In some cases the proposed scheme can actually preempt the path failure, and perform handover before it occurs. The proposed scheme has been evaluated through simulation, emulation, and within the context of a wireless environment
NGN-laboratorion verkkoliitännät
Työssä selvitettiin, miten Satakunnan ammattikorkeakoulun NGN-laboratorion verkosta voidaan tarjota palveluliitäntöjä kolmansille osapuolille. Mahdollisia palveluita olisivat esim. NGN-laboratorion älyverkkoliitäntä IN– ja CAMEL-pyynnöille, GSM-viestikeskusliitäntä, kansainvälinen verkkovierailu tai etäälle sijoitettava tukiasema. Työssä oleellinen osa oli tunnistaa palvelut, sekä selvittää tapa jolla toteuttaa niiden vaatimat yhteydet, perustuen standardiratkaisuihin, kuten SIGTRAN tai CESoPSN.This thesis investigated how to provide service connections to third parties from the NGN laboratory. Potential services could be for example the Intelligent Network access for IN and CAMEL requests, access to SMSC, international GSM roaming or a remote base station. It was essential to recognise these services and find out how those connections are realised based on standard solutions like SIGTRAN or CESoPSN
Open source integration to mobile network
The subject of this thesis was to implement application integrating to the mobile network by using open source development tools and libraries. Chosen application was Short Message Service Center (SMSC) to prove that all related protocol layers can be implemented.
Related specifications and service descriptions were investigated and needed open source software evaluated for the implementation.
Application was tested in a real mobile network. As a result of testing the conclusion was that protocol layers and service functionalities can be fully implemented using open source software
A new security extension for SCTP
In 2000, the Signaling Transport (SIGTRAN) working group of the IETF defined the Stream Control Transmission Protocol (SCTP) as a new transport protocol. SCTP is a new multi-purpose reliable transport protocol. Due to its various features and easy extensibility it is a valid option not only for already standardised applications but also in many new application scenarios. SCTP has several advantages over TCP and UDP. The analysis of already standardised as well as potential SCTP application scenarios clearly indicates that secure end-to-end transport is one of the crucial requirements for SCTP in the future. Up to now there exist two standardised SCTP security solutions which are called TLS over SCTP [37] and SCTP over IPSec [12]. The goal of this thesis was to evaluate existing SCTP security solutions and find an optimised and efficient security solution. Several drawbacks of the standardised SCTP security solutions identified during the analysis are mainly related to features distinguishing SCTP from TCP and UDP. To avoid these drawbacks a new security solution for SCTP, called Secure SCTP (S-SCTP), is proposed which integrates the cryptographic functions into SCTP. One main requirement was that S-SCTP should be fully compatible with standard SCTP while additionally providing strong security i.e. data confidentiality, integrity and authentication. This also means that all features, options and extensions available for standard SCTP have to be supported. Furthermore, S-SCTP should have advantages with respect to performance over all parameter ranges of SCTP and be user-friendly. To specify the S-SCTP protocol extension several new control messages and new message parameters have been defined. Furthermore, procedures for initialisation, rekeying, and termination of secure sessions have been specified and modelled in SDL. Based on an SCTP implementation available in our group and an open source implementation of TLS, TLS over SCTP and S-SCTP have been implemented. These implementations as well as an SCTP over IPSec configuration were used to do comparative performance studies in a lab testbed. These experiments show that the S-SCTP concept achieves its design goals. It supports all features and current extensions of SCTP. Furthermore, it avoids the inefficiencies of the other solutions over a wide range of application scenarios and protocol parameter settings
Proceedings of Seminar on Network Protocols in Operating Systems
The Linux networking stack tends to evolve rapidly, and while there are some excellent documentation written in the past, most of the past documentation gotten (at least partially) outdated over time. The seminar on Network Protocols in Operating Systems was arranged in Aalto University, fall 2012, Department of Communications and Networking to gain a better understanding of the current status of the networking implementation in the Linux kernel. The seminar had 10 participants and each participant was assigned a module from the Linux networking implementation, on which a short paper was to be written. This publications contain the final output of this work. The papers included in the publication are:
Kurnikov, Arseny: Linux kernel application interface.
Jaakkola, Antti: Implementation of transmission control protocol in Linux.
Arianfar, Somaya: TCP’s congestion control implementation in Linux kernel.
Budigere, Karthik: Linux implementation study of stream control transmission protocol.
Khattak, Fida Ullah: The IPv4 implementation of Linux kernel stack.
Boye, Magnus: Netfilter connection tracking and NAT implementation.
Korhonen, Jouni: Mobile IPv6 Linux kernel and user space.
Soininen, Jonne: Device agnostic network interface.
Kalliola, Aapo: Network device drivers in Linux.
Varis, Nuutti: Anatomy of a Linux bridge
Softswitch: el núcleo de las redes convergentes
La infraestructura de las comunicaciones públicas conmutadas en la actualidad
consiste en una variedad de diferentes redes, tecnologías y sistemas, la
mayoría de las cuales se basan sobre estructuras de conmutación de circuitos.
La tecnología evoluciona hacia redes basadas en paquetes y los proveedores
de servicio necesitan la habilidad para interconectar sus clientes sin perder la
fiabilidad, conveniencia y funcionalidad de las redes telefónicas públicas
conmutadas.
La tecnología Softswitch resulta de enfocar estas necesidades. La evolución de
las redes de comunicaciones públicas nos sitúa en las redes de conmutación
de circuitos que predominan en la actualidad, como la red pública telefónica
conmutada. Sin embargo, la próxima generación de redes nos transportará a
redes convergentes basadas en paquetes como la red Internet. La idea es
proporcionar una diversidad de servicios de comunicaciones basados en IP2
equivalentes a los servicios de redes tradicionales por su calidad y facilidad de
uso.
En dichas redes convergentes, actuales y futuras, se tienen que fijar las
normas, y los protocolos que permitan ofrecer un rango completo de servicios
de calidad sobre redes de paquetes. La definición de un estándar común es
fundamental para permitir la configuración, gestión y despliegue de servicios
extremo a extremo con calidad de operador sobre redes multi-vendedor y en un
entorno de inter-funcionamiento con distintos operadores
Reliable Server Pooling - Evaluierung, Optimierung und Erweiterung einer neuen IETF-Architektur
The Reliable Server Pooling (RSerPool) architecture currently under
standardization by the IETF RSerPool Working Group is an overlay network framework to provide server replication and session failover capabilities to applications using it. These functionalities as such are not new, but their combination into one generic, application-independent framework is. Initial goal of this thesis is to gain insight into the complex RSerPool mechanisms by performing experimental and simulative proof-of-concept tests. The further goals are to systematically validate the RSerPool architecture and its protocols, provide improvements and optimizations where necessary and propose extensions if useful. Based on these evaluations, recommendations to implementers and users of RSerPool should be provided, giving guidelines for the tuning of system parameters and the appropriate configuration of application scenarios. In particular, it is also a goal to transfer insights, optimizations and extensions of the RSerPool protocols from simulation to reality and also to bring the achievements from research into application by supporting and contributing relevant results to the IETF's ongoing RSerPool standardization process. To achieve the described goals, a prototype implementation as well as a simulation model are designed and realized at first. Using a generic application model and appropriate performance metrics, the performance of RSerPool systems in failure-free and server failure scenarios is systematically evaluated in order to identify critical parameter ranges and problematic protocol behaviour. Improvements developed as result of these performance analyses are evaluated and finally contributed into the standardization process of RSerPool
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
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Connection Robustness for Wireless Moving Networks Using Transport Layer Multi-homing
Given any form of mobility management through wireless communication, one useful enhancement is improving the reliability and robustness of transport-layer connections in a heterogeneous mobile environment. This is particularly true in the case of mobile networks with multiple vertical handovers. In this thesis, issues and challenges in mobility management for mobile terminals in such a scenario are addressed, and a number of techniques to facilitate and improve efficiency and the QoS for such a handover are proposed and investigated. These are initially considered in an end-to-end context and all protocols and changes happened in the middleware of the connection where the network is involved with handover issues and end user transparency is satisfied.
This thesis begins by investigating mobility management solutions particularly the transport layer models, also making significant observation pertinent to multi-homing for moving networks in general. A new scheme for transport layer tunnelling based on SCTP is proposed. Consequently a novel protocol to handle seamless network mobility in heterogeneous mobile networks, named nSCTP, is proposed. Efficiency of this protocol in relation to QoS for handover parameters in an end-to-end connection while wired and wireless networks are available is considered. Analytically and experimentally it has been proved that this new scheme can significantly increase the throughput, particularly when the mobile networks roam frequently. The detailed plan for the future improvements and expansion is also provided
Connection robustness for wireless moving networks using transport layer multi-homing
Given any form of mobility management through wireless communication, one useful enhancement is improving the reliability and robustness of transport-layer connections in a heterogeneous mobile environment. This is particularly true in the case of mobile networks with multiple vertical handovers. In this thesis, issues and challenges in mobility management for mobile terminals in such a scenario are addressed, and a number of techniques to facilitate and improve efficiency and the QoS for such a handover are proposed and investigated. These are initially considered in an end-to-end context and all protocols and changes happened in the middleware of the connection where the network is involved with handover issues and end user transparency is satisfied. This thesis begins by investigating mobility management solutions particularly the transport layer models, also making significant observation pertinent to multi-homing for moving networks in general. A new scheme for transport layer tunnelling based on SCTP is proposed. Consequently a novel protocol to handle seamless network mobility in heterogeneous mobile networks, named nSCTP, is proposed. Efficiency of this protocol in relation to QoS for handover parameters in an end-to-end connection while wired and wireless networks are available is considered. Analytically and experimentally it has been proved that this new scheme can significantly increase the throughput, particularly when the mobile networks roam frequently. The detailed plan for the future improvements and expansion is also provided.EThOS - Electronic Theses Online ServiceGBUnited Kingdo