Дисертації з теми "SCTP / TCP"

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Ciência da Computação
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Nas redes de dados das operadoras de telefonia celular é fundamental que o protocolo utilizado na comunicação entre terminais seja confiável e seguro e que possa prover o máximo de garantias a integridade dos dados. Os protocolos usualmente utilizados na comunidade científica fazem parte da pilha TCP/IP. O protocolo UDP não acrescenta confiabilidade à rede e apenas implementa a multiplexação. Por outro lado, o protocolo TCP tem a vantagem de ser um protocolo confiável possuindo conexões ponto-a-ponto. Na rede de telefonia celular, considera-se nas maioria das vezes o protocolo TCP e deseja-se que as vantagens de UDP existam no TCP. Desta forma, nessa dissertação optou-se pelo estudo dos protocolos SCTP e XTP por possuírem tais características em comum e acrescentar alguns diferenciais. Entre os recursos que mais de destacam no SCTP estão a transmissão de mensagens indivisíveis, múltiplos fluxos de mensagens por conexão, variação da confiabilidade das mensagens, entre outras. Por outro lado o XTP tem como características trabalhar em aplicações de alto desempenho, e por possuir similaridades com o TCP. A proposta deste trabalho de pesquisa é de prover um estudo empírico utilizando-se dos protocolos TCP, SCTP e XTP. O estudo caracteriza-se por considerar os recursos do SCTP e XTP, a fim de demonstrar em uma rede real interna de uma operadora de telefonia móvel o diferencial dos mesmos suportando protocolos de aplicação e simulando diversas condições de rede.

TCP and UDP are the most popular transport protocols used for end-end data transmission. The rapid growth of internet leads to development of many innovative applications in the current environment. Depending on the functionality of these applications, requirements of transport protocols are changing. TCP is known for its problems with Head Of Line blocking (HOL) and SYN attacks which gives reduced performance, and also doesn’t support Multi-Homing. SCTP is another transport layer protocol similar to TCP which provides end-end communication. It has some unique features like support for Multi-homing and multi-streaming. It also protects better from SYN attacks by using four-way hand shake mechanism during association establishment. As an extension to SCTP, CMT-SCTP was proposed to take full advantage of a multi-homed host by doing load sharing over multiple paths. SCTP is believed to be a next generation transport protocol. This thesis gives an overview of the SCTP protocol and its features focusing on analysing and testing of failover mechanisms provided by SCTP in multi-homed host, evaluating the transmission performance of SCTP vs TCP in a real network environment. This report also gives a theoretical analysis on how SCTP can mitigate SYN attacks by using four-way handshake mechanism and the state of art of CMT-SCTP.

With the obvious evolution and acceleration of smart grid, it is crucial for its success to rely on a solid transmission protocol among its peripherals due to its real time streaming. TCP is the well known traditional transport protocol used for a reliable transmission, and is a major player for smart grid. However, it lacks a fault tolerance transmission method that overcomes potential failures which may mitigate smart grid progress and in its turn decrease its reliability. We propose that smart grid operators utilize SCTP as the principle transport protocol for their smart grid communications, by using the two very significant characteristics offered by SCTP multi-homing and multi-streaming respectively. Thus, we argue that they can override two major obstacles caused by TCP Head of Line Blocking (HLB) and the inability of handling automatically two or more paths to a final destination. Although SCTP resembles TCP in many aspects, SCTP can definitely play a dominant role in many current and future applications due to its key features that do not exist in TCP. We have used ns2.34 simulator as the tool whom we relied on to investigate whether or not smart grid may benefit over TCP by the two SCTP features, and have analyzed the output of simulated results by using other analytical tools. As we obtain results, we argue that smart grid operators should rely on SCTP as a feasible transmission protocol instead of TCP.

Networking research and development have historically focused on increasing network throughput and path resource utilization, which particularly helped bulk applications such as file transfer and video streaming. Recent over-provisioning in the core of the Internet has facilitated the use of interactive applications like interactive web browsing, audio/video conferencing, multi- player online gaming and financial trading applications. Although the bulk applications rely on transferring data as fast as the network permits, interactive applications consume rather little bandwidth, depending instead on low latency. Recently, there has been an increasing concern in reducing latency in networking research, as the responsiveness of interactive applications directly influences the quality of experience. To appreciate the significance of latency-sensitive applications for today's Internet, we need to understand their traffic pattern and quantify their prevalence. In this thesis, we quantify the proportion of potentially latency-sensitive traffic and its development over time. Next, we show that the flow start-up mechanism in the Internet is a major source of latency for a growing proportion of traffic, as network links get faster. The loss recovery mechanism in the transport protocol is another major source of latency. To improve the performance of latency-sensitive applications, we propose and evaluate several modifications in TCP. We also investigate the possibility of prioritization at the transport layer to improve the loss recovery. The idea is to trade reliability for timeliness. We particularly examine the applicability of PR-SCTP with a focus on event logging. In our evaluation, the performance of PR-SCTP is largely influenced by small messages. We analyze the inefficiency in detail and propose several solutions. We particularly implement and evaluate one solution that utilizes the Non-Renegable Selective Acknowledgments (NR-SACKs) mechanism, which has been proposed for standardization in the IETF. According to the results, PR-SCTP with NR-SCAKs significantly improves the application performance in terms of low latency as compared to SCTP and TCP.
Interactive applications such as web browsing, audio/video conferencing, multi-player online gaming and financial trading applications do not benefit (much) from more bandwidth. Instead, they depend on low latency. Latency is a key determinant of user experience. An increasing concern for reducing latency is therefore currently being observed among the networking research community and industry. In this thesis, we quantify the proportion of potentially latency-sensitive traffic and its development over time. Next, we show that the flow start-up mechanism in the Internet is a major source of latency for a growing proportion of traffic, as network links get faster. The loss recovery mechanism in the transport protocol is another major source of latency. To improve the performance of latency-sensitive applications, we propose and evaluate several modifications in TCP. We also investigate the possibility of prioritization at the transport layer to improve the loss recovery. The idea is to trade reliability for timeliness. We particularly examine the applicability of PR-SCTP with a focus on event logging. In our evaluation, the performance of PR-SCTP is largely influenced by small messages. We analyze the inefficiency in detail and propose several solutions. We particularly implement and evaluate one solution that utilizes the Non-Renegable Selective Acknowledgments (NR-SACKs) mechanism, which has been proposed for standardization in the IETF. According to the results, PR-SCTP with NR-SCAKs significantly improves the application performance in terms of low latency as compared to SCTP and TCP.

To provide Internet applications with good performance, the transport protocol TCP is designed to optimize the throughput of data transfers. Today, however, more and more applications rely on low latency rather than throughput. Such applications can be referred to as data-limited and are not appropriately supported by TCP. Another emerging problem is associated with the use of novel networking techniques that provide infrastructure-less networking. To improve connectivity and performance in such environments, multi-path routing is often used. This form of routing can cause packets to be reordered, which in turn hurts TCP performance. To address timeliness issues for data-limited traffic, we propose and experimentally evaluate several transport protocol adaptations. For instance, we adapt the loss recovery mechanisms of both TCP and SCTP to perform faster loss detection for data-limited traffic, while preserving the standard behavior for regular traffic. Evaluations show that the proposed mechanisms are able to reduce loss recovery latency with 30-50%. We also suggest modifications to the TCP state caching mechanisms. The caching mechanisms are used to optimize new TCP connections based on the state of old ones, but do not work properly for data-limited flows. Additionally, we design a SCTP mechanism that reduces overhead by bundling several packets into one packet in a more timely fashion than the bundling normally used in SCTP. To address the problem of packet reordering we perform several experimental evaluations, using TCP and state of the art reordering mitigation techniques. Although the studied mitigation techniques are quite good in helping TCP to sustain its performance during pure packet reordering events, they do not help when other impairments like packet loss are present.

Paper V was in manuscript form at the time of the defense.

Cette thèse porte sur une solution multipath pour terminaux mobiles multi-interfaces qui permet l'utilisation de chemin de données parallèles pour obtenir un débit plus élevé ainsi qu'une fiabilité de transmission dans des réseaux sans fil hétérogènes. il propose une solution au niveau de la couche de transport appelée forward prediction scheduling (fps). fps attenue le problème de réception de données dans le désordre en estimant au préalable les retards encourus par les données sur chaque chemin candidat, puis en planifiant la transmission d'un paquet de données de telle sorte qu'il soit reçu en ligne avec les paquets provenant d'autres chemins. L'évaluation préliminaire des performances du fps est effectuée a l'aide du modèle sctp-cmt de ns-2. ceci est ensuite suivi par l'implémentation fps dans la version du noyau linux de sctp (lksctp) et par des tests utilisant un appareil mobile avec un ensemble hétérogène d'interfaces réseau filaires et sans fil. les résultats prouvent les améliorations de performances apportées par le fps face a des taux de retard de trajet élevés et a des liaisons sans fil dynamiques. Une extension inter-couches du mécanisme fps est également proposée, qui contribue a des calculs précis du délai de trajet en utilisant les informations de couche 2 dans les liaisons sans fil 802.11.enfin, une solution multiparti codage réseau axée sur la fiabilité est proposée, qui permet a un hôte multi-interface de transmettre des combinaisons de paquets de données en utilisant ses multiples chemins. à l'aide de résultats préliminaires, il est démontre que l'application du codage linéaire avec le mécanisme améliore considérablement la fiabilité
This thesis deals with a multipath solution for multi-interfaced mobile terminals that enables the use of parallel data paths to achieve higher throughput as well as transmission reliability in heterogeneous wireless networks. it proposes a transport-layer multipath solution called forward prediction scheduling (fps). fps alleviates the out-of-order data reception problem by estimating the delays incurred to data on each candidate path beforehand, and then scheduling the transmission of a data packet such that it is received in line with packets from other paths.preliminary performance evaluation of fps is carried out using ns-2's sctp-cmt model. this is then followed by fps implementation in linux kernel version of sctp (lksctp) and tests using a mobile device with heterogeneous set of wired and wireless network interfaces. the results prove the performance improvements brought by fps in face of high path delay ratios and dynamic wireless links.a cross-layer extension of fps mechanism is also proposed which contributes to accurate path delay calculations using layer-2 information in 802.11 wireless links.finally, a reliability-driven network coding multipath solution is proposed which enables a multi-interfaced host to transmit linearly encoded combinations of original data packets using its multiple paths. with the help of preliminary results, it is shown that the application of linear coding with fps mechanism significantly improves data transmission reliability as well as leads to less out-of-order reception problem

Diploma thesis deals with creation of laboratory exercises in ns-3 environment. Each one of three exercises consists of theoretical introduction and instructions to carry out the simulation. The first exercise´s topic is routing protocol BGP. The second exercise is focused on transport protocols TCP, UDP, SCTP. In the last exercise, the basic network devices and topologies are simulated. The ARP and RIPv2 protocols are simulated as well.

This thesis concerns the security of tomorrow’s peer-to-peer real-time communication in heterogeneous networks. Because of the additional delay caused by inband handshake and the poor compatibilities of some transport protocols, it was determined that existing security protocols such as transport layer security (TLS) and datagram transport layer security (DTLS) are not suitable in such a user scenario and a new security protocol should be designed. This new security protocol is called transport encapsulation security payload (TESP). TESP not only has the advantage of low initialization delay, but also fully supports transport protocols including TCP, UDP, stream control transmission protocol (SCTP), and datagram congestion control protocol (DCCP). Also a security analysis of TESP was carried out and no security flaws were found.
Denna uppsats behandlar säkerheten för morgondagens "peer-to-peer" (P2P) realtidskommunikation i heterogena nät. På grund av den adderade fördröjning som orsakas av inbandssignalering och dålig kompabilitet hos många transportprotokoll, så kan man fastställa att existerande säkerhetsprotokoll, såsom "(Datagram) Transport Layer Security" (TLS och DTLS), inte är lämpade för denna typ av kommunikation och att ett nytt säkerhetsprotokoll bör tas fram. "Transport Encapsulation Security Payload" (TESP) är ett sådant protokoll. TESP har inte bara fördelar såsom låg uppstartsfördröjning, utan har också stöd för många transportprotokoll, t.ex. "Transport Control Protocol" (TCP), "User Datagram Protocol" (UDP), "Stream Control Transmission Protocol" (SCTP) och "Datagram Congestion Control Protocol" (DCCP). Även en säkerhetsanalys av TESP har gjorts, där inga säkerhetsproblem har kunnat påvisas.

This diploma thesis focuses on theoretical and practical comparison of webpage transport protocols such as HTTP/HTTPS (Hypertext Transfer Protocol) v1.1, SPDY, HTTP/2 and QUIC using UDP (User Datagram Protocol), TCP (Transmission Control Protocol) and SCTP (Stream Control Transmission Protocol) as transport protocols. This work also contains design and manual for practical laboratory tasks on which can students verify theoretical assumptions. These tasks compares protocols in different conditions such as packet loss, latency and jitter.

Avec la démocratisation des appareils mobiles, les transports en commun sont amenés à proposer de nouveaux services à leur usagers et notamment une connexion à Internet. Le véhicule de transport en commun agit alors comme un routeur mobile fournissant une connexion fiable à ses noeuds et doit pour cela être connecté en permanence à un point d'accès. Les zones de couverture étant limitées par les technologies utilisées et par les obstacles, des changements de réseaux sont alors nécessaires et provoquant différents évènements pouvant impacter les performances des protocoles de Transport : introduction de latences dues à la configuration des interfaces, modification des caractéristiques du chemin utilisé par la communication.. Dans cette thèse nous étudions cet impact en déterminant son origine puis nous proposons des solutions visant à le réduire de deux manières : en réduisant les latences introduites par le changement de réseau et en diminuant l'impact de la modification des caractéristiques du réseau.

This thesis attempts to provide basic overview of the topic of the GSM system and tries to design Mobile Switching Centre Emulator that could perform the operation Location Update. The first part of this thesis describes the principles and specifics of the GSM network (network structure, the operations required to support user mobility, network entities, etc.). The second part of this thesis describes the SS7 signaling protocols, SIGTRAN and MAP protocol. The final part deals with design of the emulator.

This thesis presents basic structure and entities of mobile network GSM. It presents principles of signalling with focus on core network via signalling systems SS7 and SIGTRAN. Chosen protocol layers and signalling message types are presented. The thesis is concluded by the design and implementation of the application emulating home location register of mobile users.

Il lavoro è stato suddiviso in tre macro-aree. Una prima riguardante un'analisi teorica di come funzionano le intrusioni, di quali software vengono utilizzati per compierle, e di come proteggersi (usando i dispositivi che in termine generico si possono riconoscere come i firewall). Una seconda macro-area che analizza un'intrusione avvenuta dall'esterno verso dei server sensibili di una rete LAN. Questa analisi viene condotta sui file catturati dalle due interfacce di rete configurate in modalità promiscua su una sonda presente nella LAN. Le interfacce sono due per potersi interfacciare a due segmenti di LAN aventi due maschere di sotto-rete differenti. L'attacco viene analizzato mediante vari software. Si può infatti definire una terza parte del lavoro, la parte dove vengono analizzati i file catturati dalle due interfacce con i software che prima si occupano di analizzare i dati di contenuto completo, come Wireshark, poi dei software che si occupano di analizzare i dati di sessione che sono stati trattati con Argus, e infine i dati di tipo statistico che sono stati trattati con Ntop. Il penultimo capitolo, quello prima delle conclusioni, invece tratta l'installazione di Nagios, e la sua configurazione per il monitoraggio attraverso plugin dello spazio di disco rimanente su una macchina agent remota, e sui servizi MySql e DNS. Ovviamente Nagios può essere configurato per monitorare ogni tipo di servizio offerto sulla rete.

MPI middleware glues together the components necessary for execution. A l most all implementations have a communication component also called a message progression layer that progresses outstanding messages and maintains their state. The goal of this work is to thin or eliminate this communication component by pushing the functionality down onto the standard IP stack in order to take advantage of potential advances in commodity networking. We introduce a TCP-based design that successfully eliminates the communication component. We discuss how this eliminated TCP-based design doesn't scale and show a more scalable design based on the Stream Control Transmission Protocol (SCTP) that has a thinned communication component. We compare the designs showing why SCTP one-to-many sockets in their current form can only thin and not completely eliminate the communication component. We show what additional features would be required of SCTP to enable a practical design with a fully eliminated communication component.
Science, Faculty of
Computer Science, Department of
Graduate

碩士
中興大學
電機工程學系所
95
SCTP(Stream Control Transmission Protocol), a new fourth layer transport protocol, was proposed by the SIGTRAN Working Group of the IETF(Internet Engineering Task Force). The protocol is a connection-oriented and reliable transport service. It also supports multi-homing and multi-streaming mechanisms and can improve the transmission efficiency and enhance the security of traditional TCP. In this thesis we will focus on the congestion control for TCP (Transmission Control Protocol) (Tahoe, NewReno, SACK) and SCTP(SCTP, NewReno) and will compare the performance issue on delivery. We use the NS-2(Network Simulator-Version 2), a network simulation software, to simulate several scenarios of packet loss and congestion window size. The number of packets received, throughput and distribution of packet loss was simulated under two fourth layer transport protocol existing at the same time. The simulation results shows that the design of congestion control of SCTP is better than using TCP. The SCTP can not only reduce the probability of packet loss, but also improve the performance of delivery than TCP while face the suffering of multiple packet loss.