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On the Effectiveness of PR-SCTP in Networks with Competing Traffic
Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.ORCID iD: 0000-0003-2765-7873
Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
2011 (English)In: 2011 IEEE SYMPOSIUM ON COMPUTERS AND COMMUNICATIONS (ISCC), Corfu, Greece: IEEE conference proceedings, 2011Conference paper, (Refereed)
Abstract [en]

PR-SCTP is an extension to SCTP for partial reliability that enables a content sensitive transport service where the reliability of messages can be individually controlled. In previous work, PR-SCTP has been applied for prioritization of messages and trading of reliability against timeliness for applications such as real time video streaming, IPTV transmission, SIP signaling, and syslog. As compared to TCP, it has been shown to provide significant reductions in message transfer delay and gains in application performance. Much of the previous work has, however, considered artificial loss scenarios without competing traffic. Experiments presented in this paper show that although PR-SCTP clearly outperforms TCP in artificial loss scenarios, the performance gain is not as evident in scenarios where PR-SCTP shares a bottleneck link with competing traffic. Our analysis shows that inefficiencies in the \emph{forward\_tsn} mechanism of PR-SCTP, overhead due to small messages, and a higher loss rate per byte encountered by PR-SCTP are contributing factors to the reduced performance when network resources are shared. Finally, a proposal for a more efficient \emph{forward\_tsn} mechanism is introduced

Place, publisher, year, edition, pages
Corfu, Greece: IEEE conference proceedings, 2011.
Series
IEEE Symposium on Computers and Communications ISCC
National Category
Computer Science Telecommunications
Research subject
Computer Science
Identifiers
URN: urn:nbn:se:kau:diva-10925ISI: 000298614900157OAI: oai:DiVA.org:kau-10925DiVA: diva2:494484
Conference
The IEEE symposium on Computers and Communications (ISCC 2011), Corfu, GREECE, Date: JUN 28-JUL 01, 2011
Available from: 2012-02-08 Created: 2012-02-08 Last updated: 2016-08-12Bibliographically approved
In thesis
1. Performance Analysis and Improvement of PR-SCTP in an Event Logging Context
Open this publication in new window or tab >>Performance Analysis and Improvement of PR-SCTP in an Event Logging Context
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Due to certain shortcomings in TCP and UDP, the Stream Control Transmission Protocol (SCTP) was defined for transporting telephony signaling traffic. The partially reliable extension of SCTP, PR-SCTP, has been considered as a candidate for prioritizing content sensitive traffic and trading reliability against timeliness for applications with soft real time requirements. 

 

In this thesis, we investigate the applicability of PR-SCTP for event logging applications. Event logs are inherently prioritized. This makes PR-SCTP a promising candidate for transporting event logs. However, the performance gain of PR-SCTP can be very limited when application message sizes are small and messages have mixed reliability requirements. Several factors influence PR-SCTP’s performance. One key factor is the inefficiency in the forward_tsn mechanism of PR-SCTP. We examine the inefficiency in detail and propose several solutions. Moreover, we implement and evaluate one solution that utilizes the Non-Renegable Selective Acknowledgements (NR-SACKs) mechanism currently being standardized in the IETF, which is available in the FreeBSD operating system. Our results show a significant performance gain for PR-SCTP with NR-SACKs. In some scenarios, the average message transfer delay is reduced by more than 75%. Moreover, we evaluate NR-SACK based PR-SCTP using real traces from an event logging application called syslog. It significantly improves the syslog application performance as compared to SCTP, TCP and UDP.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2012. 35 p.
Series
Karlstad University Studies, ISSN 1403-8099 ; 2012:44
National Category
Computer Science
Research subject
Computer Science
Identifiers
urn:nbn:se:kau:diva-14676 (URN)978-91-7063-451-2 (ISBN)
Presentation
2012-11-01, 21A342, Karlstads universitet, Karlstad, 10:15 (English)
Opponent
Supervisors
Available from: 2012-10-15 Created: 2012-09-06 Last updated: 2015-11-12Bibliographically approved
2. Towards a Low Latency Internet: Understanding and Solutions
Open this publication in new window or tab >>Towards a Low Latency Internet: Understanding and Solutions
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

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.

Abstract [en]

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.

Place, publisher, year, edition, pages
Karlstad: Karlstad University Press, 2015. 39 p.
Series
Karlstad University Studies, ISSN 1403-8099 ; 41
Keyword
latency; traffic classification; slow-start; TCP; SCTP; PR-SCTP; NR-SACKs; event logging; performance evaluation
National Category
Computer Science
Research subject
Computer Science
Identifiers
urn:nbn:se:kau:diva-37487 (URN)978-91-7063-659-2 (ISBN)
Public defence
2015-11-12, Lagerlöfsalen, 1A305, Karlstads universitet, 09:00 (English)
Opponent
Supervisors
Available from: 2015-10-16 Created: 2015-08-14 Last updated: 2015-11-12Bibliographically approved

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