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| 2. |
- Rajiullah, Mohammad, 1981-, et al.
(författare)
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Syslog Performance : Data Modeling and Transport
- 2011
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Ingår i: Proceedings of the 3rd International Workshop on Security and Communication Networks (IWSCN 2011). - Norway : IEEE Press. ; , s. 31-37
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Konferensbidrag (refereegranskat)abstract
- Syslog is one of the basic methods for event logging in computer networks. Log messages that are generated by syslog can be used for a number of purposes, including optimizing system performance, system auditing, and investigating malicious activities in a computer network. Considering all these attractive uses, both timeliness and reliability is needed when syslog messages are transported over a network. The unreliable transport protocol UDP was specified in the original syslog specification; later a reliable transport service based on TCP was also proposed. However, TCP is a costly alternative in terms of delay. In our previous work, we introduced the partially reliable extension of SCTP, PR-SCTP, as a transport service for syslog, trading reliability against timeliness by prioritizing syslog messages. In this work, we first model syslog data using real syslog traces from an operational network. The model is then used as input in the performance evaluation of PR-SCTP. In the experiments, real congestion is introduced in the network by running several competing flows. Although PR-SCTP clearly outperformed TCP and SCTP in our previous work, our present evaluations show that PR-SCTP performance is largely influenced by the syslog data size characteristics
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| 3. |
- Budzisz, Łukasz, et al.
(författare)
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A taxonomy and survey of SCTP research
- 2012
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Ingår i: ACM Computing Surveys. - New York : ACM Press. - 0360-0300 .- 1557-7341. ; 44:4, s. -36
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Tidskriftsartikel (refereegranskat)abstract
- The Stream Control Transmission Protocol (SCTP) is a relatively recent general-purpose transport layer protocol for IP networks that has been introduced as a complement to the well-established TCP and UDP transport protocols. Although initially conceived for the transport of PSTN signaling messages over IP networks, the introduction of key features in SCTP, such as multihoming and multistreaming, has spurred considerable research interest surrounding SCTP and its applicability to different networking scenarios. This article aims to provide a detailed survey of one of these new features—multihoming—which, as it is shown, is the subject of evaluation in more than half of all published SCTP-related articles. To this end, the article first summarizes and organizes SCTP-related research conducted so far by developing a four-dimensional taxonomy reflecting the (1) protocol feature examined, (2) application area, (3) network environment, and (4) study approach. Over 430 SCTP-related publications have been analyzed and classified according to the proposed taxonomy. As a result, a clear perspective on this research area in the decade since the first protocol standardization in 2000 is given, covering both current and future research trends. On continuation, a detailed survey of the SCTP multihoming feature is provided, examining possible applications of multihoming, such as robustness, handover support, and loadsharing.
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| 4. |
- di stasi, Giovanni, et al.
(författare)
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Combining Multi-Path Forwarding and Packet Aggregation for Improved Network Performance in Wireless Mesh Networks
- 2014
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Ingår i: Computer Networks. - : Elsevier. - 1389-1286 .- 1872-7069. ; 68, s. 26-37
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Tidskriftsartikel (refereegranskat)abstract
- Wireless mesh networks (WMNs) based on the IEEE 802.11 standard are becoming increasingly popular as a viable alternative to wired networks. WMNs can cover large or difficult to reach areas with low deployment and management costs. Several multi-path routing algorithms have been proposed for such kind of networks with the objective of load balancing the traffic across the network and providing robustness against node or link failures. Packet aggregation has also been proposed to reduce the overhead associated with the transmission of frames, which is not negligible in IEEE 802.11 networks. Unfortunately, multi-path routing and packet aggregation do not work well together, as they pursue different objectives. Indeed, while multi-path routing tends to spread packets among several next-hops, packet aggregation works more efficiently when several packets (destined to the same next-hop) are aggregated and sent together in a single MAC frame. In this paper, we propose a technique, called aggregation aware forwarding, that can be applied to existing multi-path routing algorithms to allow them to effectively exploit packet aggregation so as to increase their network performance. In particular, the proposed technique does not modify the path computation phase,but it just influences the forwarding decisions by taking the state of the sending queues into account.We demonstrated our proposed technique by applying it to Layer-2.5, a multi-path routing and forwarding paradigm for WMNs that has been previously proposed.We conducted a thorough performance evaluation by means of the ns-3 network simulator, which showed that our technique allows to increase the performance both in terms of network throughput and end-to-end delay.
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| 5. |
- Eklund, Johan, 1966-, et al.
(författare)
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Delay Penalty during SCTP Handover
- 2011
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Konferensbidrag (refereegranskat)abstract
- The rapidly growing interest in untethered Internet connections such as WLAN and 3G/4G mobile connections,calls for intelligent session management, not least in terms of handovers. As part of an effort to develop a SCTP-based session management framework, we are studying ways of improving the SCTP handover delay forreal-time traffic by optimizing the startup delay on the handover-target path. We have developed a theoretical model that predicts the transfer times of SCTP messages during the startup on a new path. This paper validates our model. It shows that the model can be used to predict message transfer times in variable bitrate flows. The paper further employs our model to study the startup delay penalty during handover for the spectrum of network conditions considered relevant for real-time traffic over mobile connections.
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| 6. |
- Eklund, Johan, 1966-, et al.
(författare)
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Impact of slow start on SCTP handover performance
- 2011
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Ingår i: Proc Int Conf Comput Commun Networks ICCCN. - : IEEE conference proceedings. - 9781457706387
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Konferensbidrag (refereegranskat)abstract
- The rapidly growing interest in untethered Internet connections, especially in terms of WLAN and 3G/4G mobile connections, calls for intelligent session management: a mobile device should be able to provide a reasonable end-user experience despite location changes, disconnection periods and, not least, handovers. As part of an effort to develop a SCTP-based session management framework that meets these criteria, we are studying ways of improving the SCTP handover delay for real-time traffic; especially the startup delay on the connection between a mobile device and the target access point. To obtain an appreciation of the theoretically feasible gains of optimizing the startup delay on the handover-target path, we have developed a model that predicts the transfer times of SCTP messages during slow start. This paper experimentally validates our model and demonstrates that it could be used to predict the message transfer times in a variable bitrate flow by approximating the variable flow with a constant dito. It also employs our model to obtain an appreciation of the startup delay penalties incured by slow start during handovers in typical mobile, real-time traffic scenarios.
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| 7. |
- Garcia, Johan, 1970-, et al.
(författare)
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A Measurement Based Study of TCP Protocol Efficiency in Cellular Networks
- 2014
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Ingår i: Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks (WiOpt), 2014 12th International Symposium on. - : IEEE. - 9783901882630 ; , s. 131-136
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Konferensbidrag (refereegranskat)abstract
- This paper examines the efficiency of resource utilization with respect to short-lived TCP flows in various cellular networks. The examination is done from the vantage point of an end-user who would like to use as much as possible of the cellular transmission resources that are available at any given time, thus minimizing the delays associated with communication. Based on a comprehensive measurement campaign we first derive network characteristics with regards to base RTT, RTT under load, and average throughput. A protocol efficiency metric is introduced to capture how efficiently short TCP flows are in fact able to use the instantaneously available transmission resources in a cellular network. The measurements show that short TCP connections have low efficiency in 3. SG (HSPA+) and 4G (LTE) mobile broadband networks, and that the improved latency and throughput characteristics of 4G in relation to 3. SG nevertheless results in lower short-flow efficiency for 4G.
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| 8. |
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| 9. |
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| 10. |
- Rajiullah, Mohammad, 1981-, et al.
(författare)
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Optimizing PR-SCTP Performance using NR-SACKs
- 2012
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Ingår i: 2012 2nd Baltic Congress on Future Internet Communications. - Vilnius : IEEE conference proceedings. - 9781467316729 ; , s. 222-229
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Konferensbidrag (refereegranskat)abstract
- A partially reliable extension of SCTP, PR-SCTP, has been considered as a candidate for prioritizing content sensitive traffic at the transport layer. PR-SCTP offers a flexible QoS trade-off between timeliness and reliability. Several applications such as streaming multimedia, IPTV transmission, and SIP signaling have been shown to benefit from this. Our previous work, however, suggests that the performance gain can be very much reduced in a network with competing traffic. One of the most important factors in this case is the inefficiency in the forward_tsn mechanism in PR-SCTP. In this paper, we thoroughly examine the forward_tsn inefficiency and propose a solution to overcome it that takes advantage of the NR-SACKs mechanism available in FreeBSD. Moreover, we implement and evaluate the proposed solution. Our initial set of 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%.
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