Congestion control in networks with no congestion drops

2007

We discuss congestion control algorithms, using network awareness as a criterion to categorize different approaches. The first category ("the box is black") consists of a group of algorithms that consider the network as black box, assuming no knowledge of its state, other than the binary feedback upon congestion. The second category ("the box is grey") groups approaches that use measurements to estimate available bandwidth, level of contention or even the temporary characteristics of congestion. Due to the possibility of wrong estimations and measurements, the network is considered a grey box. The third category ("the box is green") contains the bimodal congestion control, which calculates explicitly the fair-share, as well as the network-assisted control, where the network communicates its state to the transport layer; the box now is becoming green.

IEEE Transactions on Computers, 2014

At present, companies and standards organizations are enhancing Ethernet as the unified switch fabric for all of the TCP/IP traffic, the storage traffic and the high performance computing traffic in data centers. Backward congestion notification (BCN) is the basic mechanism for the end-to-end congestion management enhancement of Ethernet. To fulfill the special requirements of the unified switch fabric, i.e., losslessness and low transmission delay, BCN should hold the buffer occupancy around a target point tightly. Thus, the stability of the control loop and the buffer size are critical to BCN. Currently, the impacts of delay on the performance of BCN are unidentified. When the speed of Ethernet increases to 40 Gbps or 100 Gbps in the near future, the number of on-the-fly packets becomes the same order with the buffer size of switch. Accordingly, the impacts of delay will become significant. In this paper, we analyze BCN, paying special attention on the delay. We model the BCN system with a set of segmented delayed differential equations, and then deduce sufficient condition for the uniformly asymptotic stability of BCN. Subsequently, the bounds of buffer occupancy are estimated, which provides direct guidelines on setting buffer size. Finally, numerical analysis and experiments on the NetFPGA platform verify our theoretical analysis.

Due to the recent trends in Internet, for exchange of information in the form of pure data traffic and multimedia traffic, High-speed network is necessary. As there is a growing demand for high-speed networks, data transfer must take place without any congestion. In data networking and queueing theory, Network congestion occurs when a link or node is carrying so much data that its quality of service deteriorates. Typical effects include queueing delay, packet loss or the blocking of new connections. A consequence of these latter two is that incremental increases in offered load lead either only to small increase in network throughput, or to an actual reduction in network throughput. The Transmission Control Protocol (TCP) is one of the core protocols of the Internet Protocol Suite. TCP has not performed well on high-speed network because the standard TCP's algorithm for congestion control may cause thousands of packet drops in one Round Trip Time (RTT) and the window size is halved at the time of congestion. So the utilization of the bandwidth and throughput is minimized. The researchers developed different TCP variants to improve the performance of the congestion control algorithms in high-speed network. In this paper we propose a sequence of algorithms based on window adjustment, feedback mechanism and buffer management to overcome the limitations for high-speed network. The congestion control mechanism that we adopt starts with Queue Management, which enables to modify and control the transmission queue. The Window Adjustment Mechanism alters the Congestion window size based on the Input load. The Feedback mechanism renders the optimum load that can be serviced currently when congestion had taken place. Also the feedback information is notified to the sender. This solution to control the congestion in the network achieves maximum throughput and bandwidth utilization, with minimum delay and drop probability. The performance of the congestion window, throughput, utilization of the bandwidth, delay are analyzed and presented.

2014

Congestion control is one of the most important concerns in computer networks. There is a chance of inefficient usages of resources, possibly leading to network collapse if we do not use the proper congestion control algorithm. Therefore congestion control is an effort to readjust the performance of a network to fluctuations in the traffic load without adversely affecting user’s perceived service quality. Computer networks are presently dominated by pure end-to-end feedback or implicit feedback congestion control. This approach has worked admirably but the networks are evolving and the traffic mix and amount has increased tremendously with the advent of multimedia applications in the Internet. Hence explicit help from within the network like switches or routers is crucial especially during congestion time. Active queue management (AQM) is a method which hand over congestion feedback from routers to end users. Explicit congestion notification (ECN) is an alternate approach which is m...

IEEE/ACM Transactions on Networking, 2005

This paper is aimed at designing a congestion control system that scales gracefully with network capacity, providing high utilization, low queueing delay, dynamic stability, and fairness among users. The focus is on developing decentralized control laws at end-systems and routers at the level of fluid-flow models, that can provably satisfy such properties in arbitrary networks, and subsequently approximate these features through practical packet-level implementations. Two families of control laws are developed. The first "dual" control law is able to achieve the first three objectives for arbitrary networks and delays, but is forced to constrain the resource allocation policy. We subsequently develop a "primal-dual" law that overcomes this limitation and allows sources to match their steady-state preferences at a slower timescale , provided a bound on round-triptimes is known. We develop two packet-level implementations of this protocol, using 1) ECN marking, and 2) queueing delay, as means of communicating the congestion measure from links to sources. We demonstrate using ns-2 simulations the stability of the protocol and its equilibrium features in terms of utilization, queueing and fairness, under a variety of scaling parameters.

Modern computer networks, including the Internet, are being designed for fast transmission of large amounts of data, for which Congestion Control Algorithms (CCAs) are very important. Without proper CCAs, congestion collapse of such networks is a real possibility. In Network the data packets that have different quality-of-service requirements. By buffering submitted packets at gateway nodes we can regulate the rates at which data packets enter the network, although this may increase the overall packet delays to an unacceptable level. Therefore it is increasingly important to develop gateway mechanisms that are able to keep throughput of a network high, while maintaining sufficiently small average queue lengths. Several algorithms proposed recently try to provide an efficient solution to the problem. In one of these, Active Queue Management (AQM) with Explicit Congestion Notification (ECN), packets generated by different data sources are marked at the network’s gateways. In other algorithms, packets are dropped to avoid and control congestion at gateways. This paper presents a brief and breadth wise survey of major CCAs designed to operate at the gateway routers of Networks.

International Journal of Scientific & Technology Research, 2013

ACM Transactions on Computer Systems ( …, 1990

We propose a scheme for congestion auoidunce in networks using a connectionless protocol at the network layer. The scheme uses a minimal amount of feedback from the network to the users, who adjust the amount of traffic allowed into the network. The routers in the network detect congestion and set a congestion-indication bit on packets flowing in the forward direction. The congestion indication is communicated back to the users through the transport-level acknowledgment. The scheme is distributed, adapts to the dynamic state of the network, converges to the optimal operating point, is quite simple to implement, and has low overhead. The scheme maintains fairness in service provided to multiple sources. This paper presents the scheme and the analysis that went into the choice of the various decision mechanisms. We also address the performance of the scheme under transient changes in the network and pathological overload conditions. * 159

1990

Computer Networks, 2011

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