scholarly journals Early Window Tailoring: A New Approach to Increase the Number of TCP Connections Served

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Marcos Talau ◽  
Mauro Fonseca ◽  
Emilio C. G. Wille
Keyword(s):  
Congestion Control ◽  
Loss Rate ◽  
New Approach ◽  
Window Management ◽  
Multiple Devices ◽  
Congestion Control Mechanism ◽  
Tcp Connections ◽  
Multiple Scenarios ◽  
Very High ◽  
Better Than

In the absence of losses, TCP constantly increases the amount of data sent per instant of time. This behavior leads to problems that affect its performance, especially when multiple devices share the same gateway. Several studies have been done to mitigate such problems, but many of them require TCP side changes or a meticulous configuration. Some studies have shown promise, such as the use of gateway techniques to change the receiver’s advertised window of ACK segments based on the amount of memory in the gateway; in this work, we use the term “network-return” to refer to these techniques. In this paper, we present a new network-return technique called early window tailoring (EWT). For its use, it does not require any modification in the TCP implementations at the sides and does not require that all routers in the path use the same congestion control mechanism, and the use in the gateway is sufficient. With the use of the simulator ns-3 and following the recommendations of RFC 7928, the new approach was tested in multiple scenarios. The EWT was compared to drop-tail, RED, ARED, and the two network-return techniques—explicit window adaptation (EWA) and active window management (AWM). In the results, it was observed that EWT was shown to be efficient in congestion control. Its use avoided losses of segments, bringing expressive gains in the transfer latency and goodput and maintaining fairness between the flows. However, unlike other approaches, the most prominent feature of EWT is its ability to maintain a very high number of active flows at a given level of segment loss rate. The EWT allowed the existence of a number of flows, which is on average 49.3% better than its best competitor and 75.8% better when no AQM scheme was used.

RUN-TIME ADJUSTED CONGESTION CONTROL FOR MULTIMEDIA: EXPERIMENTALS RESULTS

2004 ◽  
Vol 05 (03) ◽  
pp. 249-266
Author(s):  
GIUSEPPE DE MARCO ◽  
MAURIZIO LONGO ◽  
FABIO POSTIGLIONE
Keyword(s):  
Congestion Control ◽  
Multimedia Data ◽  
Network Resources ◽  
Average Throughput ◽  
Congestion Control Algorithm ◽  
Adequate Quality ◽  
Run Time ◽  
Congestion Control Mechanism ◽  
Tcp Connections

Multimedia communications over Internet should achieve adequate quality of service (QoS) while maintaining 'fairness' in network resources allocation with respect to competing connections. The fairness is usually achieved by means of the congestion control, which could induce high variations on the perceived throughput and then affecting the QoS. On the other hand, the variations of throughput of the multimedia communication can be neglected if a minimum average throughput is guaranteed to the playout buffer used by the application. These considerations can be exploited to solve the conflicting requirements of fairness and QoS. The transport protocol proposed here is a modified version of the window-based datagram congestion control protocol, that implements a TCP-like congestion control mechanism wherein the multiplicative decrease of the congestion window is controlled by a non-linear function. Experimental results show that this modified congestion control algorithm, which in turn is adjusted at run-time based on the estimated mean round-trip time, is capable to provide the average throughput required by the encoding technique adopted for the multimedia data compression, while guaranteeing the required fairness with respect to competing TCP connections.

scholarly journals A practical approach to lake water density from electrical conductivity and temperature

2016 ◽  
Vol 20 (7) ◽  
pp. 2975-2986 ◽  
Author(s):  
Santiago Moreira ◽  
Martin Schultze ◽  
Karsten Rahn ◽  
Bertram Boehrer
Keyword(s):  
Electrical Conductivity ◽  
Common Procedure ◽  
New Approach ◽  
Circulation Patterns ◽  
Lakes And Reservoirs ◽  
High Concentrations ◽  
Lake Waters ◽  
Very High ◽  
Limited Accuracy ◽  
Better Than

Abstract. Density calculations are essential to study stratification, circulation patterns, internal wave formation and other aspects of hydrodynamics in lakes and reservoirs. Currently, the most common procedure is the use of CTD (conductivity, temperature and depth) profilers and the conversion of measurements of temperature and electrical conductivity into density. In limnic waters, such approaches are of limited accuracy if they do not consider lake-specific composition of solutes, as we show. A new approach is presented to correlate density and electrical conductivity, using only two specific coefficients based on the composition of solutes. First, it is necessary to evaluate the lake-specific coefficients connecting electrical conductivity with density. Once these coefficients have been obtained, density can easily be calculated based on CTD data. The new method has been tested against measured values and the most common equations used in the calculation of density in limnic and ocean conditions. The results show that our new approach can reproduce the density contribution of solutes with a relative error of less than 10 % in lake waters from very low to very high concentrations as well as in lakes of very particular water chemistry, which is better than all commonly implemented density calculations in lakes. Finally, a web link is provided for downloading the corresponding density calculator.

scholarly journals Smart-RED: A Novel Congestion Control Mechanism for High Throughput and Low Queuing Delay

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Armir Bujari ◽  
Andrea Marin ◽  
Claudio E. Palazzi ◽  
Sabina Rossi
Keyword(s):  
Congestion Control ◽  
Control Mechanism ◽  
Mean Field ◽  
Main Idea ◽  
Access Point ◽  
Congestion Avoidance ◽  
Bandwidth Utilization ◽  
Queuing Delay ◽  
Congestion Control Mechanism ◽  
Tcp Connections

We consider the scenario in which several TCP connections share the same access point (AP) and a congestion avoidance/control mechanism is adopted with the aim of assigning the available bandwidth to the clients with a certain fairness. When UDP traffic with real-time requirements is present, the problem becomes even more challenging. Very well-known congestion avoidance mechanisms are the Random Early Detection (RED) and the Explicit Congestion Notification (ECN). More recently, the Smart Access Point with Limited Advertised Window (SAP-LAW) has been proposed. Its main idea is that of computing the maximum TCP rate for each connection at the bottleneck, taking into account the UDP traffic to keep a low queue size combined with a reasonable bandwidth utilization. In this paper, we propose a new congestion control mechanism, namely, Smart-RED, inspired by SAP-LAW heuristic formula. We study its performance by using mean field models and compare the behaviours of ECN/RED, SAP-LAW, and Smart-RED under different scenarios. We show that while Smart-RED maintains some of the desirable properties of the SAP-LAW, it solves the problems it may have in case of bursty UDP traffic or TCP connections with very different needs of bandwidth.

scholarly journals P4QCN: Congestion Control Using P4-Capable Device in Data Center Networks

Electronics ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 280
Author(s):  
Junjie Geng ◽  
Jinyao Yan ◽  
Yuan Zhang
Keyword(s):  
Congestion Control ◽  
Data Center ◽  
Control Mechanism ◽  
Direct Memory Access ◽  
Coarse Grained ◽  
Transport Protocol ◽  
Expected Performance ◽  
Control Scheme ◽  
Congestion Control Mechanism ◽  
Very High

Modern data centers aim to offer very high throughput and ultra-low latency to meet the demands of applications such as online intensive services. Traditional TCP/IP stacks cannot meet these requirements due to their high CPU overhead and high-latency. Remote Direct Memory Access (RDMA) is an approach that can be designed to meet this demand. The mainstream transport protocol of RDMA over Ethernet is RoCE (RDMA over Converged Ethernet), which relies on Priority Flow Control (PFC) within the network to enable a lossless network. However, PFC is a coarse-grained protocol which can lead to problems such as congestion spreading, head-of-the-line blocking. A congestion control protocol that can alleviate these problems of PFC is needed. We propose a protocol, called P4QCN for this purpose. P4QCN is a congestion control scheme for RoCE and it is an improved Quantized Congestion Notification (QCN) design based on P4, which is a flow-level, rate-based congestion control mechanism. P4QCN extends the QCN protocol to make it compatible with IP-routed networks based on a framework of P4 and adopts a two-point algorithm architecture which is more effective than the three-point architecture used in QCN and Data Center QCN(DCQCN). Experiments show that our proposed P4QCN algorithm achieves the expected performance in terms of latency and throughput.

scholarly journals Coap based Congestion Control Mechanism For Low Power Iot Networks

2019 ◽  
Vol 8 (10) ◽  
pp. 958-962
Keyword(s):  
Congestion Control ◽  
Control Mechanism ◽  
Protocol Stack ◽  
Application Layer ◽  
Round Trip ◽  
Trip Time ◽  
Time Out ◽  
Simple Change ◽  
Congestion Control Mechanism ◽  
Better Than

Internet of Things has billions of connected devices into internet. CoAP is a Constrained Protocol used in application layer of IoT Protocol Stack. CoAP is running on top of User Datagram Protocol (UDP), which means that, there is no possibility of congestion control in it, so CoAP is responsible for Congestion control mechanism. UDP has no knowledge on congestion control. IoT has significant resource constraint, due to this there are lots of design challenges in IoT network. This paper proposes a simple change in the CoAP protocol named CoCoA (CoAP Simple Congestion Control / Advance). CoCoA introduces novel Round Trip Time (RTT), VBF (Variable Back off Factor) and aging mechanism to calculate the dynamic and controlled Retransmission Time Out (RTO) for IoT Networks. This paper compared with the existing all the congestion control mechanism and the implementation result shows that the proposed mechanism is better than the existing mechanism in terms of throughput, power consumption, memory foot print and fairness index.

A new approach based on graph matching and evolutionary approach for sport scheduling problem

2020 ◽  
pp. 1-16
Author(s):  
Meriem Khelifa ◽  
Dalila Boughaci ◽  
Esma Aïmeur
Keyword(s):  
Graph Matching ◽  
State Of The Art ◽  
Travel Cost ◽  
Round Robin ◽  
New Approach ◽  
Traveling Tournament Problem ◽  
Significant Interest ◽  
National League ◽  
Better Than

The Traveling Tournament Problem (TTP) is concerned with finding a double round-robin tournament schedule that minimizes the total distances traveled by the teams. It has attracted significant interest recently since a favorable TTP schedule can result in significant savings for the league. This paper proposes an original evolutionary algorithm for TTP. We first propose a quick and effective constructive algorithm to construct a Double Round Robin Tournament (DRRT) schedule with low travel cost. We then describe an enhanced genetic algorithm with a new crossover operator to improve the travel cost of the generated schedules. A new heuristic for ordering efficiently the scheduled rounds is also proposed. The latter leads to significant enhancement in the quality of the schedules. The overall method is evaluated on publicly available standard benchmarks and compared with other techniques for TTP and UTTP (Unconstrained Traveling Tournament Problem). The computational experiment shows that the proposed approach could build very good solutions comparable to other state-of-the-art approaches or better than the current best solutions on UTTP. Further, our method provides new valuable solutions to some unsolved UTTP instances and outperforms prior methods for all US National League (NL) instances.

An Improved Congestion Control Mechanism Based on Mobile Agent for Wireless Sensor Networks

2014 ◽  
Vol 519-520 ◽  
pp. 1239-1242
Author(s):  
Xiao Hu Yu
Keyword(s):  
Wireless Sensor Networks ◽  
Sensor Networks ◽  
Congestion Control ◽  
Mobile Agent ◽  
Mobile Agents ◽  
Control Mechanism ◽  
Wireless Sensor ◽  
Delivery Ratio ◽  
Routing Table ◽  
Congestion Control Mechanism

An improved congestion control mechanism based on mobile agent for wireless sensor networks is proposed, which includes node-level congestion and link-level congestion control. The formers congestion information is collected and distributed by mobile agents (MA). When mobile agent travels through the networks, it can select a less-loaded neighbor node as its next hop and update the routing table according to the nodes congestion status. Minimum package of node outgoing traffic was preferentially transmitted in the link-level congestion. Simulation result shows that proposed mechanism attains high delivery ratio and throughput with reduced delay when compared with the existing technique.

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