TCP's protocol radius: the distance where timers prevent communication (original) (raw)
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Performance of TCP protocols in deep space communication networks
IEEE Communications Letters, 2002
The communication requirements for space missions necessitate to address the problems due to deep space communication networks. In this letter, the effects of slow start algorithm, propagation delay and the link errors on the throughput performance of transport layer protocols are investigated in deep space communication networks. The objective of this letter is to demonstrate through experimental results that existing TCP protocols are far from satisfying the deep space communication requirements and point out the urgent need for new TCP solutions.
ACM SIGMETRICS Performance Evaluation Review, 2008
TCP has traditionally been considered unfriendly for realtime applications. Nonetheless, popular applications such as Skype use TCP since UDP packets cannot pass through many NATs and firewalls. Motivated by this observation, we study the delay performance of TCP for real-time media flows. We develop an analytical performance model for the delay of TCP. We use extensive experiments to validate the model and to evaluate the impact of various TCP mechanisms on its delay performance. Based on our results, we derive the working region for VoIP and live video streaming applications and provide guidelines for delay-friendly TCP settings. Our research indicates that simple application-level schemes, such as packet splitting and parallel connections, can reduce the delay of real-time TCP flows by as much as 30% and 90%, respectively.
TCP with sender-based delay control
International Symposium on Computers and Communications, 2002
This paper describes a congestion control method for TCP that adjusts the trans-mission rate of a TCP connection by changing not only the congestion window size as in normal TCP, but also by delaying the transmission of packets at the sender. We refer to this method as TCP with sender-based delay control, or simply SDC. SDC can keep the window
Delay Resistant Transport Protocol for Deep Space Communication
Int'l J. of Communications, Network and System Sciences, 2011
The throughput of conventional transport protocols suffers significant degradation with the increased Round Trip Time (RTT) typically seen in deep space communication. This paper proposes a Delay Resistant Transport Protocol (DR-TCP) for point-to-point communication in deep space exploration missions. The issues related to deep space communication protocol design and the areas where modifications are necessary are investigated, and a protocol is designed that can provide good throughput to the applications using a deep space link. The proposed protocol uses a cross layer based approach to find the allocated bandwidth and avoids initial bandwidth estimation. A novel timeout algorithm estimates the timeout duration with an objective to maximize throughput and avoid spurious timeout events. The protocol is evaluated through extensive simulations in ns2 considering high RTT values typically seen in Lunar and Mars Exploration Networks under different conditions of packet error rates. DR-TCP provides a significant increase in the throughput as compared to traditional transport protocols under the same conditions. A novel adaptive redundant retransmission algorithm is also presented to take care of the high PER in deep space links. The effect of the Retransmission Frequency has been critically analyzed considering both Lunar and Deep Space scenarios under different levels of PER. The results are very encouraging even in high error conditions. The protocol exhibits a RTT independent behavior in throughput, which is the most desirable quality of a protocol for deep space communication.
DTTP: a Delay-Tolerant Transport Protocol for Space Internetworks
2nd ERCIM Workshop on …, 2008
We propose Delay-Tolerant Transport Protocol (DTTP) to address reliable data transfer in stressed network environments, such as space communications. Since existing TCP mechanisms do not work well (or at all) for such networks, new transport schemes are required. Intermittent connectivity in space environments calls for new transport approaches that smoothly adapt to the special networking conditions. DTTP is primarily a transport layer protocol and satisfies the inherent architecture requirements of Delay Tolerant Networking (DTN) in the absence of IP network infrastructure. It allows for reliable, efficient data transfer offering a number of application-oriented transmission strategies. Otherwise, when an IP architecture exists, DTTP operates as a standalone transport entity which interfaces with IP directly. We introduce the protocol's properties and functionality that enable its deployment in challenged networks. We conduct simulations that demonstrate the protocol's efficiency in scenarios with: (i) long propagation delays, (ii) minimum to relatively high packet error-rate, and (iii) intermittent connectivity.
Comparison of methods for accelerating the response time of TCP sessions over long delay paths
2013 IEEE Symposium on Computers and Communications (ISCC), 2013
Many modern Internet applications require fast client-server interaction to maximise user interactivity. This need has caused new work to be proposed to working groups of the Internet Engineering Task Force (IETF), which seek to remove bottlenecks when starting sessions. RFC 6298 improves Transmission Control Protocol (TCP) responsiveness by retransmitting lost SYNs, or first data segments sent after the three-way handshake (3WHS), with a reduced initial retransmission timeout (RTO) of 1 second from the previous value of 3 seconds. This benefits a large number of Internet connections. However, there is growing use of wireless and other long-haul radio technologies that yield round trip times (RTT) greater than 1 second. This means a significant number of connections will suffer spurious retransmissions with associated performance penalties. This paper examines whether RFC 6298 can cooperate with a set of proposed methods to extend performance benefits to long delay paths that may experience startup loss. It was found that a slight modification of TCP congestion-state initialization after the 3WHS significantly improves performance, especially if combined with SYN duplication and an increased Initial Window (IW). We further explain how a deprecated proposal to seed the RTO based on the SYN round trip time (RTT) can be updated to become suited for general deployment. Proposed modifications are evaluated, by analysis and using ns2 simulations, showing improved overall responsiveness for short delay paths as well as networks paths with shared bandwidth and appreciable delay (e.g. wireless/satellite networks).
Improving TCP Performance over Long Delay Satellite Links
2001
TCP is robust and flexible when operated on wired terrestrial networks. There are problems, however, when TCP is used on long delay satellite links. In this paper, we first study the effects that these long delays have on TCP, and then we present a transport layer solution that is implemented in OPNET 7.0. This solution enables TCP to share congestion control information among connections between the same host-pair. The shared information is used to speed up new connections to the same destination, and to coordinate concurrent connections in order to reduce the possibility of congestion losses. Simulation results show that, with the presence of information about the same channel discovered by previous connections, this solution performs better than standard TCP. As the delay increases, the degree of performance improvement also increases, making this approach particularly well-suited for long delay satellite links.
Characterizing End-to-End Delay Performance of Randomized TCP Using an Analytical Model
International Journal of Advanced Computer Science and Applications, 2016
TCP (Transmission Control Protocol) is the main transport protocol used in high speed network. In the OSI Model, TCP exists in the Transport Layer and it serves as a connection-oriented protocol which performs handshaking to create a connection. In addition, TCP provides end-to-end reliability. There are different standard variants of TCP (e.g. TCP Reno, TCP NewReno etc.)which implement mechanisms to dynamically control the size of congestion window but they do not have any control on the sending time of successive packets. TCP pacing introduces the concept of controlling the packet sending time at TCP sources to reduce packet loss in a bursty traffic network. Randomized TCP is a new TCP pacing scheme which has shown better performance (considering throughput, fairness) over other TCP variants in bursty networks. The end-to-end delay of Randomized TCP is a very important performance measure which has not yet been addressed. In the current high speed networks, it is increasingly important to have mechanisms that keep end-to-end to delay within an acceptable range. In this paper, we present the performance evaluation of end-to-end delay of Randomized TCP. To this end, we have used an analytical and a simulation model to characterize the end-to-end delay performance of Randomized TCP.
On tuning tcp for superior performance on high speed path scenarios
Transmission control protocol performance varies considerably, depending on network and path conditions. In this paper, we discuss path conditions that affect TCP performance, from round trip delays to path capacity and buffering. We characterize throughput performance of popular TCP congestion avoidance mechanism as well as recently proposed TCP variants via open source based network experiments. We show that superior TCP performance may be achieved via careful selection of congestion avoidance mechanism, as well as parameter tuning.