The Experts below are selected from a list of 12708 Experts worldwide ranked by ideXlab platform
Sanghwa Chung - One of the best experts on this subject based on the ideXlab platform.
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a sender side algorithm for handling retransmission timeouts of tcp newreno over multi hop wireless networks
Advanced Information Networking and Applications, 2013Co-Authors: S Prasanthi, Meejeong Lee, Sanghwa ChungAbstract:In today's Internet, New Reno is the most widely deployed connection oriented Transport Layer Protocol. However, the performance of New Reno degrades significantly when New Reno operates in Multi-hop Wireless Networks (MWNs). Frequent retransmission timeouts, which is one of the well-known problems of the performance degradation of New Reno over MWNs. In MWNs, retransmission timeout is unavoidable when multiple packets are lost from one window of data during fast recovery. In this paper, we propose a sender side algorithm, called SRA (Sudden Recovery Algorithm) for handling retransmission timeouts due to the multiple losses of newly sent packets during fast recovery and thereby improve the performance of New Reno over MWNs. Simulation results show that SRA achieves significant improvements in throughput than current TCP versions especially when retransmission timeouts happens during fast recovery.
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a new tcp mechanism for reducing retransmission timeouts over multi hop wireless networks
ACM Symposium on Applied Computing, 2011Co-Authors: S Prasanthi, Sanghwa ChungAbstract:Transmission Control Protocol (TCP) is the most popular Transport Layer Protocol used in the current internet. However, the end-to-end throughput of TCP degrades significantly with increase in number of hops in multi-hop wireless networks. Improving the performance of TCP from frequent retransmission timeouts, which is one of the well-known problems of the end-to-end throughput degradation of TCP over multi-hop wireless networks. The loss of newly sent packets during fast recovery cannot be recovered by fast retransmission, if the sender does not have enough duplicate acknowledgments and this may lead to retransmission timeouts. In this paper, we propose a new TCP mechanism, called R-RTO (Reduction of Retransmission Timeouts) having the features of TCP NewReno, which is capable of recovering packets without waiting for retransmission timeouts and thereby increase the throughput of TCP. Our proposed mechanism consists of two schemes, called Rapid Retransmission (RR) and Estimation of Available Bandwidth (EAB). Through extensive simulations using qualnet 4.5, the results show that our mechanism achieves 10--30% improvement than key existing TCP variants.
Thomas Dreibholz - One of the best experts on this subject based on the ideXlab platform.
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evaluation and optimisation of multi path Transport using the stream control transmission Protocol
2012Co-Authors: Thomas DreibholzAbstract:The Stream Control Transmission Protocol (SCTP) as defined in RFC 4960 is an advanced Transport Layer Protocol that provides support for multi-homing. That is, SCTP endpoints may simultaneously use multiple Network Layer addresses, which allows to connect the endpoints to multiple networks for redundancy purposes. However, for the transfer of user data, only one of the possible paths is currently used at a time. All other paths remain as backup and are only used for retransmissions. Clearly, the existence of multiple paths has led to the idea of applying load sharing among the paths. An extension to SCTP -- denoted as Concurrent Multipath Transfer (CMT) -- realises this load sharing functionality. While this approach works well for similar paths, i.e. paths having similar characteristics regarding bandwidths, bit error rates and delays, the use of dissimilar paths does not work that neatly. In this thesis, the issues of dissimilar paths for CMT-based load sharing will be demonstrated first. The reasons for these issues will be identified and solutions proposed. These solutions will be evaluated in simulations, as well as partially also in a real-world Internet testbed setup, in order to show their effectiveness. In particular, it will be shown that a combination of multiple mechanisms is necessary to make CMT work as expected under a wide range of network and system parameters. Furthermore, the fairness of CMT-based Transport -- in concurrency to classic non-CMT flows -- will be analysed. The usage of plain CMT leads to an overly aggressive bandwidth occupation on so-called shared bottlenecks. As a countermeasure, the idea of Resource Pooling will be utilised. For this purpose, two new and one adapted congestion control approach -- all based on the Resource Pooling principle -- will be introduced and examined in similar as well as dissimilar path setups, in order to show how to fairly deploy CMT Transport in the Internet. The results of this work have also been contributed to the ongoing IETF standardisation process of SCTP and its extensions.
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evaluation and optimisation of multi path Transport using the stream control transmission Protocol
2012Co-Authors: Thomas DreibholzAbstract:The Stream Control Transmission Protocol (SCTP) as defined in RFC 4960 is an advanced Transport Layer Protocol that provides support for multi-homing. That is, SCTP endpoints may simultaneously use multiple Network Layer addresses, which allows to connect the endpoints to multiple networks for redundancy purposes. However, for the transfer of user data, only one of the possible paths is currently used at a time. All other paths remain as backup and are only used for retransmissions. Clearly, the existence of multiple paths has led to the idea of applying load sharing among the paths. An extension to SCTP -- denoted as Concurrent Multipath Transfer (CMT) -- realises this load sharing functionality. While this approach works well for similar paths, i.e. paths having similar characteristics regarding bandwidths, bit error rates and delays, the use of dissimilar paths does not work that neatly. In this thesis, the issues of dissimilar paths for CMT-based load sharing will be demonstrated first. The reasons for these issues will be identified and solutions proposed. These solutions will be evaluated in simulations, as well as partially also in a real-world Internet testbed setup, in order to show their effectiveness. In particular, it will be shown that a combination of multiple mechanisms is necessary to make CMT work as expected under a wide range of network and system parameters. Furthermore, the fairness of CMT-based Transport -- in concurrency to classic non-CMT flows -- will be analysed. The usage of plain CMT leads to an overly aggressive bandwidth occupation on so-called shared bottlenecks. As a countermeasure, the idea of Resource Pooling will be utilised. For this purpose, two new and one adapted congestion control approach -- all based on the Resource Pooling principle -- will be introduced and examined in similar as well as dissimilar path setups, in order to show how to fairly deploy CMT Transport in the Internet. The results of this work have also been contributed to the ongoing IETF standardisation process of SCTP and its extensions.
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Stream control transmission Protocol: Past, current, and future standardization activities
IEEE Communications Magazine, 2011Co-Authors: Thomas Dreibholz, Michael Tuxen, Irene Rungeler, Erwin P. Rathgeb, Robin Seggelmann, R R StewartAbstract:The Stream Control Transmission Protocol (SCTP) is a general-purpose Transport Layer Protocol providing a service similar to TCP - plus a set of advanced features to utilize the enhanced capabilities of modern IP networks and to support increased application requirements. Nowadays, there are SCTP implementations for all major operating systems. While SCTP was standardized as an RFC several years ago, there is still significant ongoing work within the IETF to discuss and standardize further features in the form of Protocol extensions. In this article, we first introduce the SCTP base Protocol and already standardized extensions. After that, we focus on the ongoing SCTP standardization progress in the IETF and give an overview of activities and challenges in the areas of security and concurrent multipath Transport.
S Prasanthi - One of the best experts on this subject based on the ideXlab platform.
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a sender side algorithm for handling retransmission timeouts of tcp newreno over multi hop wireless networks
Advanced Information Networking and Applications, 2013Co-Authors: S Prasanthi, Meejeong Lee, Sanghwa ChungAbstract:In today's Internet, New Reno is the most widely deployed connection oriented Transport Layer Protocol. However, the performance of New Reno degrades significantly when New Reno operates in Multi-hop Wireless Networks (MWNs). Frequent retransmission timeouts, which is one of the well-known problems of the performance degradation of New Reno over MWNs. In MWNs, retransmission timeout is unavoidable when multiple packets are lost from one window of data during fast recovery. In this paper, we propose a sender side algorithm, called SRA (Sudden Recovery Algorithm) for handling retransmission timeouts due to the multiple losses of newly sent packets during fast recovery and thereby improve the performance of New Reno over MWNs. Simulation results show that SRA achieves significant improvements in throughput than current TCP versions especially when retransmission timeouts happens during fast recovery.
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a new tcp mechanism for reducing retransmission timeouts over multi hop wireless networks
ACM Symposium on Applied Computing, 2011Co-Authors: S Prasanthi, Sanghwa ChungAbstract:Transmission Control Protocol (TCP) is the most popular Transport Layer Protocol used in the current internet. However, the end-to-end throughput of TCP degrades significantly with increase in number of hops in multi-hop wireless networks. Improving the performance of TCP from frequent retransmission timeouts, which is one of the well-known problems of the end-to-end throughput degradation of TCP over multi-hop wireless networks. The loss of newly sent packets during fast recovery cannot be recovered by fast retransmission, if the sender does not have enough duplicate acknowledgments and this may lead to retransmission timeouts. In this paper, we propose a new TCP mechanism, called R-RTO (Reduction of Retransmission Timeouts) having the features of TCP NewReno, which is capable of recovering packets without waiting for retransmission timeouts and thereby increase the throughput of TCP. Our proposed mechanism consists of two schemes, called Rapid Retransmission (RR) and Estimation of Available Bandwidth (EAB). Through extensive simulations using qualnet 4.5, the results show that our mechanism achieves 10--30% improvement than key existing TCP variants.
Raghupathy Sivakumar - One of the best experts on this subject based on the ideXlab platform.
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ptcp an end to end Transport Layer Protocol for striped connections
International Conference on Network Protocols, 2002Co-Authors: Hungyun Hsieh, Raghupathy SivakumarAbstract:The TCP Transport Layer Protocol is designed for connections that traverse a single path between the sender and receiver. However there are several environments in which multiple paths can be used by a connection simultaneously. We consider the problem of supporting striped connections that operate over multiple paths. We propose an end-to-end Transport Layer Protocol called pTCP (parallel TCP) that allows connections to enjoy the aggregate bandwidths offered by the multiple paths, irrespective of the individual characteristics of the paths. We show that pTCP can have a varied range of applications through instantiations in three different environments: (a) bandwidth aggregation on multi-homed mobile hosts; (b) service differentiation using purely end-to-end mechanisms; (c) end-systems based network striping. In each of the applications, we demonstrate the applicability of pTCP and how its efficacy compares with existing approaches through simulation results.
Rahul Singh - One of the best experts on this subject based on the ideXlab platform.
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a survey on tcp transmission control Protocol and udp user datagram Protocol over aodv routing Protocol
International Journal of Research, 2014Co-Authors: Robin Singh, Praveen Tripathi, Rahul SinghAbstract:A mobile Ad-hoc network (MANET) is a collection of wireless nodes aimed at information exchange and resource sharing. The Ad hoc On-Demand Distance Vector (AODV) a well-known and widely used Protocol for MANETs. This paper presents the study of TCP and UDP (two Transport Layer Protocols) over AODV in a Mobile Ad hoc Network. The study is done on the TCP and UDP Transport Layer Protocol and performance metrics like QoS defines a guarantee given by the network to satisfy a set of predetermined service performance constraints for the user in terms of end-to-end delay, jitter, and available bandwidth. Therefore, routing Protocols must be feasible for all kinds of constrained applications to run well in a MANET. However, it is a significant technical challenge to define a comprehensive framework for QoS support, due to dynamic topology, distributed management and multi-hop connections for MANETs.
