Congestion Control Protocol Research Articles

A Proactive Transport Protocol for Performance Enhancement of Satellite based Networks

satellite networks mainly due to the effect of long propagation delays and high link error rates. In this paper a new congestion control protocol for satellite networks is proposed. The protocol uses a proactive approach and is composed of novel ideas like Proactive Slow Start, Proactive Congestion Avoidance and Decision based Error handling policies that are combined with traditional TCP algorithms like Fast Retransmit. The mainstay of our protocol is that the nature of the RTT pattern can give us probable indication of an incipient congestion in the network. This changing pattern of RTT is incidentally used to differentiate between congestion or link error, thus avoiding unnecessary rate throttle. In the initial phase necessary augmentation of ns2 simulator pertaining to the proposed protocol is carried out. This was essential to create a necessary test bed for exhaustive simulation of the protocol considering a GEO network with different congestion level and packet error rate. Simulation results show that the protocol always outperforms other TCP schemes in terms of goodput and in cases an improvement of 80% to 120% is observed especially when the packet error rate is very high. Evaluation of the protocol shows a high fairness property and excellent adaptability to high levels of congestion and errors.

Root Cause Analysis of Congestion in Wireless Sensor Network

ABSTRACT In wireless sensor networks data, which get generated, is not always same; some data may be more important than others and having different priorities. As deployment sizes and data rates grow, congestion becomes a major problem in these networks. The congestion results in arbitrary dropping of data packets that reduce the overall network throughput. In this paper, we discuss the various parameters (root causes of congestion), which help us to avoid and control the congestion in the wireless sensor network. The parameters consider in this paper are input/output flow rate, node density, non-linear or unbalanced distribution of load, processing / service time of node and reliability of network. Categories and Subject Descriptors Wireless Communication General Terms Algorithms, Reliability Keywords Wireless Sensor Network, Congestion control and avoidances. 1. INTRODUCTION Wireless sensor Network consist of small microcontroller fitted with sensors and some means of communication radios. They are distributed over wide area and transmit gathered data to one or many central nodes called as Sink or also know as base station. Wireless sensor network (WSN) is one of the emerging research areas that provide designated services such as disaster prevention, environment monitoring, medical monitoring, habitat monitoring, military surveillance, inventory tracking, intelligent logistics, and health monitoring. These networks deliver numerous types of traffic, from simple periodic reports to unpredictable bursts of messages due to this congestion control in wireless sensor network is very rare event. Congestion occurs in WSN due to i) Radio channel interference, ii) Addition and removal of sensor nodes, iii) Lastly sensed event cause bursts of messages. WSNs have some problems to be overcome, for example energy-conservation congestion control, reliability data dissemination, and security. These problems often involve in one or several layers top-down from application layer to physical layer, and can be studies separately in each corresponding layer, or collaboratively cross each layer. One of the important problem, congestion control may involve in only transport layer, but energy-conservation may be related to physical layer, data link layer, network layer, and high layers. Many researchers recently turn their attentions to transport layer protocols, which are important for reliable data dissemination and energy-conservation for WSNs. Congestion causes many problems when sensors receives more packets than that its buffer space, the excess packets has to be dropped energy consumed by sensor nodes on the packet is wasted. And if further packet has traveled, the more waste is, which in turn diminish the network throughput and reliable data transmissions. Congestion control studies how to recover from congestion. Congestion avoidance studies how to prevent congestion from happening for this we have to monitor the parameters which can helps us to avoid congestion in WSN which is the subject of this paper.The remainder of the paper is organized as follows. Section 2 lists existing congestion control protocol. Section 3 present parameters, which help to avoid congestion. And lastly Section 4 concludes the whole paper on the note of future work.

Equation-based end-to-end single-rate multicast congestion control

Among the recently proposed single-rate multicast congestion control protocols is transmission control protocol-friendly multicast congestion control (TFMCC; Widmer and Handley 2001; Floyd et al. 2000; Widmer et al. IEEE Netw 15:28–37, 2001), which is an equation-based single-rate protocol that extends the mechanisms of the unicast TCP-friendly rate control (TFRC) protocol into the multicast domain. In TFMCC, each receiver estimates its throughput using an equation that estimates the steady-state throughput of a TCP source. The source then adjusts its sending rate according to the slowest receiver within the session (a.k.a., current-limiting receiver, CLR). TFMCC is a relatively simple, scalable, and TCP-friendly multicast congestion control protocol. However, TFMCC is hindering its throughput performance by adopting an equation derived from the unicast TFRC protocol. Further, TFMCC is slow to react to congestion conditions that usually result in a change of the CLR. This paper is motivated by these two observations and proposes an improved version of TFMCC, which we refer to as hybrid-TFMCC (or H-TFMCC for short). First, each receiver estimates its throughput using an equation that models the steady-state throughput of a multicast source controlled according to the additive increase multiplicative decrease (AIMD) approach. The second modification consists of adopting a hybrid sender/receiver-based rate control strategy, where the sending rate can be adjusted by the source or initiated by the current or a new CLR. The source monitors RTT variations on the CLR path, in order to rapidly adjust the sending rate to network conditions. Simulation results show that these modifications result in remarkable performance improvement with respect to throughput, time to react, and magnitude of oscillations. We also show that H-TFMCC remains TCP-friendly and achieves a higher fairness index than that achieved by TFMCC.

Elastic Routing Table with Provable Performance for Congestion Control in DHT Networks

Consistent hashing-based DHT networks have an inherent load balancing problem. The problem becomes more severe in heterogeneous networks with nonuniform and time-varying popular files. Existing DHT load balancing algorithms are mainly focused on the issues caused by node heterogeneity. To deal with skewed lookups, this paper presents an elastic routing table (ERT) mechanism for query load balancing, based on the observation that high-degree nodes tend to receive more traffic load. The mechanism allows each node to have a routing table of variable size corresponding to node capacities. The indegree and outdegree of the routing table can also be adjusted dynamically in response to the change of file popularity and network churn. Theoretical analysis proves that the routing table degree is bounded. The ERT mechanism facilitates locality-aware randomized query forwarding to further improve lookup efficiency. By relating query forwarding to a supermarket customer service model, we prove that a two-way randomized query forwarding policy should lead to an exponential improvement in query processing time over random walking. Simulation results demonstrate the effectiveness of the ERT mechanism and its related query forwarding policy for congestion and query load balancing. In comparison with existing virtual-server?-based load balancing algorithms and other routing table control approaches, the ERT-based congestion control protocol yields significant improvement in query lookup efficiency.

Performance of Multirate Multicast in Distributed Network

The number of Internet users has increased very rapidly due to the scalability of the network. The users demand for higher bandwidth and better throughput in the case of on demand video, or video conference or any real time distributed network system. Performance is a great issue in any distributed networks. In this paper we have shown the performance of the multicast groups or clusters in the distributed network system. In this paper we have shown the performance of different users or receivers belongs to the multicast group or cluster in the distributed network, transfer data from the source node with multirate multicast or unirate multicast by considering packet level forwarding procedure in different sessions. In this work we have shown that how the throughput was effected when the number of receiver increase. In this work we have considered the different types of queue such as RED, Fair queue at the junction node for maintaining the end to end packet transmission. In this work we have used various congestion control protocol at the sender nodes. This paper we have shown the performance of the distributed cluster network by multirate multicast.

Model Checking Optimisation Based Congestion Control Algorithms

Model checking has been widely applied to the verification of network protocols. Alternatively, optimisation based approaches have been proposed to reason about the large scale dynamics of networks, particularly with regard to congestion and rate control protocols such as TCP. This paper intends to provide a first bridge and explore synergies between these two approaches. We consider a series of discrete approximations to the optimisation based congestion control algorithms. Then we use branching time temporal logic to specify formally the convergence criteria for the system dynamics and present results from implementing these algorithms on a state-of-the-art model checker. We report on our experiences in using the abstraction of model checking to capture features of the continuous dynamics typical of optimisation based approaches.

A model-driven emulation approach to large-scale TCP performance evaluation

Small-scale experiments are insufficient for a comprehensive study of congestion control protocols. Similarly, results obtained from pure simulation platforms without exercising real protocols and applications lack realism. Motivated by these reasons, we developed scalable virtualised evaluation environment for TCP (SVEET), a TCP performance evaluation testbed where real implementations of TCP variants can be accurately evaluated under diverse network configurations and workloads from real applications in large-scale network settings. It is our purpose to provide the research community a standard environment through which quantitative assessment regarding TCP behaviour can be drawn from large-scale experiments. In order to accomplish our goal, we adopted a novel model-driven emulation approach combining real-time simulation, machine and time virtualisation techniques. We validate the testbed via extensive experiments to assess its potentials and limitations. Additionally, we performed case studies involving real web, streaming and peer-to-peer applications. Our results indicate that SVEET can accurately model the behaviour of the TCP variants and support large-scale network scenarios.

A Hop by Hop Congestion Control Protocol to Mitigate Traffic Contention in Wireless Sensor Networks

A Hop by Hop Congestion Control Protocol to Mitigate Traffic Contention in Wireless Sensor Networks

DAMCC: Improved multi-rate multicast congestion control protocol

A new Dynamic Allocation bandwidth strategy for Multicast Congestion Control(DAMCC) was put forward.Concerning the current problems of adjusting the rate of granularity roughly and inadequate application about the Receiver-driven Layered Congestion control(RLC),this strategy designed an algorithm,which can calculate the rate of the enhancement layer dynamically and separately.The receiver of the strategy of DAMCC can calculate the value of the Round-Trip Time(RTT) according to the feedback response information,then calculate its own TCP friendly rate and receive the multicast data at the corresponding rate to achieve sharing the network resources with TCP flow fairly.The simulation results show DAMCC strategy can use network bandwidth more effectively than the RLC strategy,and it also solves the problem of network bandwidth heterogeneity.Besides,it can calculate the TCP friendly rate at the receiver to achieve sharing the network resources with the TCP flow fairly.

A Fairness-Aware Congestion Control Scheme in Wireless Sensor Networks

The event-driven nature of wireless sensor networks (WSNs) leads to unpredictable network load. As a result, congestion may occur at sensors that receive more data than they can forward, which causes energy waste, throughput reduction, and packet loss. In this paper, we propose a rate-based fairness-aware congestion control (FACC) protocol, which controls congestion and achieves approximately fair bandwidth allocation for different flows. In FACC, we categorize intermediate relaying sensor nodes into near-source nodes and near-sink nodes. Near-source nodes maintain a per-flow state and allocate an approximately fair rate to each passing flow. On the other hand, near-sink nodes do not need to maintain a per-flow state and use a lightweight probabilistic dropping algorithm based on queue occupancy and hit frequency. Our simulation results and analysis show that FACC provides better performance than previous approaches in terms of throughput, packet loss, energy efficiency, and fairness.

Transport Protocol Throughput Fairness

Interest continues to grow in alternative transport protocols to the Transmission Control Protocol (TCP). These alternatives include protocols designed to give greater efficiency in high-speed, high-delay environments (so-called high-speed TCP variants), and protocols that provide congestion control without reliability. For the former category, along with the deployed base of ‘vanilla’ TCP – TCP NewReno – the TCP variants BIC and CUBIC are widely used within Linux: for the latter category, the Datagram Congestion Control Protocol (DCCP) is currently on the IETF Standards Track. It is clear that future traffic patterns will consist of a mix of flows from these protocols (and others). So, it is important for users and network operators to be aware of the impact that these protocols may have on users. We show the measurement of fairness in throughput performance of DCCP Congestion Control ID 2 (CCID2) relative to TCP NewReno, and variants Binary Increase Congestion control (BIC), CUBIC and Compound, all in “out-of-the box” configurations. We use a testbed and endto- end measurements to assess overall throughput, and also to assess fairness – how well these protocols might respond to each other when operating over the same end-to-end network path. We find that, in our testbed, DCCP CCID2 shows good fairness with NewReno, while BIC, CUBIC and Compound show unfairness above round-trip times of 25ms.

Generalized stochastic performance models for loss-based congestion control

In this paper, we propose a generalized framework for modeling the behavior of prominent congestion-control protocols. Specifically, we define a general class of loss-based congestion-control (LB-CC) mechanisms and demonstrate that many variants of TCP, including those being proposed for high-speed networks, belong to this class. Second, we develop a stochastic model to predict the transfer time for bulk transmissions by any protocol belonging to the LB-CC class—our model predicts both the mean as well as the variability in the transfer time. Our model is applicable to a wide set of transfer types and network capacities. We validate our model through extensive simulations under controlled settings, as well as with comprehensive HTTP workloads. We use our empirical analysis to also provide insights into several important issues, including: (i) identifying the settings under which previously-proposed TCP models are accurate, and (ii) identifying the conditions under which only steady-state analysis can be sufficient in modeling transfer performance. Our generalized framework provides a powerful tool that can be used in the design, analysis, and comparison of next-generation transport protocols. We demonstrate this benefit by comparing prominent TCP proposals for high-speed networks.

MPCP

In the recent years, end-to-end feedback-based variants of TCP as well as VCP have emerged as practical alternatives of congestion control by requiring the use of only one or two ECN bits in the IP header. However, all such schemes suffer from a relatively low speed of convergence and exhibit a biased fairness behavior in moderate bandwidth high delay networks due to utilizing an insufficient amount of congestion feedback. In this paper, we propose a novel distributed ECN-based congestion control protocol to which we refer as Multi Packet Congestion Control Protocol (MPCP). In contrast to other alternatives, MPCP is able to relay a more precise congestion feedback yet preserve the utilization of the two ECN bits. MPCP distributes (extracts) congestion related information into (from) a series of n packets, thus allowing for a 2n-bit quantization of congestion measures with each packet carrying two of 2n bits in its ECN bits. We describe the design, implementation, and performance evaluation of MPCP through both simulations and experimental studies.

Improved method of TCP-friendly congestion control protocol

TCP Friendly Rate Control(TFRC) is a congestion control mechanism designed for non-TCP flows.Due to that not all losses are related to congestion in wireless network,to adopt initial TFRC will induce maloperations.In the paper,biased queue method was used to distinguish congestion losses from random losses.It would prevent unnecessary congestion control and would improve the quality of transmission in wireless networks.Through simulations and experiments,it is found that the method can greatly improve the stability of transport rate,finally accomplishes QoS of application layer.

A result on second order nonlinear operators arising in high-speed networking applications

We consider the behaviour of a class of nonlinear difference equations that arise in networks employing congestion control protocols. For a class of such systems we show that trajectories, experiencing the same set of congestion notifications, but starting at different initial conditions, converge exponentially to each other.

A Multievent Congestion Control Protocol for Wireless Sensor Networks

Wireless sensor networks are application-dependent networks. An application may require general event region information, pernode event region information, or prioritized event information in case of multiple events. All event flows are subject to congestion in wireless sensor networks. This is due to the sudden impulse of information flow from a number of event nodes to a single destination. Congestion degrades system throughput and results in energy loss of nodes. In this paper, we present a multievent congestion control protocol (MCCP) for wireless sensor networks. MCCP supports multiple event reporting modes, that is, general event reporting, per-node fair event reporting, and prioritized multiple event reporting. MCCP efficiently mitigates congestion and provides output according to selected event reporting mode. MCCP uses hop-by-hop packet delivery time and buffer size as the basic metrics for congestion detection. Moreover, we introduce a schedule-based scheme at the transport layer for rate assignment and ordered delivery of event packets to underlying routing layer. This helps to avoid packet collisions and increases the packet delivery ratio even in high densities. Detailed simulation analysis confirms that MCCP decreases packet drops and provides high packet delivery ratio (above 90%) for multiple event reporting modes.

Application-level QoS: improving video conferencing quality through sending the best packet next

In a traditional network stack, data is transmitted in the order that it is received. An algorithm is proposed where priority of packets and expiry times is used by the transport layer to reorder or discard packets to optimise the use of available bandwidth. This scheme is implemented and compared to unmodified Datagram Congestion Control Protocol (DCCP) using traffic modelled on video conferencing software. The results show improvement can be made during periods of congestion – more audio packets arrive on time and in many cases video packet arrival rates also increase.

Towards experimental evaluation of explicit congestion control

Innovative efforts to provide a clean-slate design of congestion control for future high-speed heterogeneous networks have recently led to the development of explicit congestion control. These methods rely on multi-byte router feedback and aim to contribute to the design of a more scalable Internet of tomorrow. However, experimental evaluation and deployment experience with these approaches is still limited to either low bandwidth networks or simple topologies. In addition, all existing implementations are exclusively applicable to either rate- or window-based protocols and are unable to study performance of different protocols on a common platform. This paper aims to fill this void by designing a unified Linux implementation framework for both rate- and window-based methods that does not incur any interference with the system's network stack or applications. Using this implementation, we implement and reveal several key properties of four recent explicit congestion control protocols XCP, JetMax, RCP, and PIQI-RCP using Emulab's gigabit testbed with a ariety of simple yet representative network topologies. Our experiments not only confirm the known behavior of these methods, but also demonstrate their previously undocumented properties (e.g., RCP's transient overshoot under abrupt traffic load changes and JetMax's low utilization in the presence mice flows).

Performance Evaluation of End-to-End Congestion Control Protocols

Performance Evaluation of End-to-End Congestion Control Protocols

A NOVEL SPECTRUM OF EPOCH CONVERGENT CONGESTION CONTROL

Achieving efficient and fairness bandwidth allocations among connections in high bandwidth delay product networks has been a daunting challenge. Addressing the deficiency of previous protocols, this paper presents a novel spectrum of Epoch Convergent Congestion Control protocols for deployment in high speed and long distance networks. Most of the end to end high speed protocols that has been presented can be seen as a member of ECCC. Through extensive analysis of ECCC, we focus on SQUARE, one of the protocols in Epoch Convergent Congestion Control. Without the need to revise the current end-to-end architecture, SQUARE is shown to be efficient when there is bandwidth available, to be fair when many flows compete with each other for the same bottleneck, to be friendly when deployed with the conventional TCP, to be robust when there are oscillations in the network.