Class-Based Weighted Fair Queuing Research Articles

Quality of service class mapping and scheduling scheme for converged LTE-WiFi in the next generation networks

In this paper, a novel quality of service (QoS) class mapping and scheduling scheme for the LTE-WiFi converged network is proposed to ensure that end-to-end QoS support is provisioned seamlessly. A mapping among QoS classes of LTE and WiFi is performed first, then scheduling scheme is outlined. For scheduling scheme, traffic is separated into real-time (RT) and non-real-time (NRT) components, then a two-stage complex queuing strategy is performed. In the first stage, deficit weighted round robin queuing (DWRRQ) and class-based weighted fair queuing (CBWFQ) are used for RT and NRT applications respectively to segregate and forward traffic according to resource requirements. Whereas in the second stage, rate-control priority queuing (RCPQ) is used for all types of traffic to give each class appropriate priority level. Performance evaluation of the converged network was done based on different metrics such as jitter, end-to-end delay, throughput, and packet loss ratio. Simulation results show significant improvements for RT with slight degradation on NRT applications after using the new scheduling scheme.

Enhanced low latency queuing algorithm with active queue management for multimedia applications in wireless networks

Low cost broadband services used widely in the recent years increased the demand for multimedia applications. Many of these applications require different quality of service (QoS) in terms of throughput and delay. In the current resource constrained wireless networks, resource management plays a vital role. In order to handle the resources effectively and to increase the QoS, proper packet scheduling algorithms need to be developed. Low latency queuing (LLQ) is a packet scheduling algorithm which combines strict priority queuing (SPQ) to class-based weighted fair queuing (CBWFQ). In this paper, an enhanced low latency queuing (ELLQ) algorithm is proposed in which an additional SPQ is introduced along with the existing SPQ. Further, the QoS is improved by integrating congestion avoidance algorithm with ELLQ. Simulation results using the OPNET modeller show that the proposed algorithm outperforms the existing algorithm in terms of throughput and delay for the multimedia applications.

Enhanced low latency queuing algorithm with active queue management for multimedia applications in wireless networks

Low cost broadband services used widely in the recent years increased the demand for multimedia applications. Many of these applications require different quality of service (QoS) in terms of throughput and delay. In the current resource constrained wireless networks, resource management plays a vital role. In order to handle the resources effectively and to increase the QoS, proper packet scheduling algorithms need to be developed. Low latency queuing (LLQ) is a packet scheduling algorithm which combines strict priority queuing (SPQ) to class-based weighted fair queuing (CBWFQ). In this paper, an enhanced low latency queuing (ELLQ) algorithm is proposed in which an additional SPQ is introduced along with the existing SPQ. Further, the QoS is improved by integrating congestion avoidance algorithm with ELLQ. Simulation results using the OPNET modeller show that the proposed algorithm outperforms the existing algorithm in terms of throughput and delay for the multimedia applications.

Numerical Key Results for Studying the Performance of TCP Traffic under Class-Based Weighted Fair Queuing System

This paper presents a fluid model to estimate the performances of TCP traffics under a two CBWFQ (class-based weighted fair queuing) with variable rate. The system is then equivalent to two virtual links with variable capacities. At first, we give some results to evaluate the performance of TCP traffics under Best Effort architecture, then we try to exploit these results to provide key results to qualify performances characteristics of TCP traffic under CBWFQ system. The core of our analysis is based on some numerical observations and relies on the conservation of the average total number of flows carried by the system. Detailed packet level simulations of TCP flows show the accuracy of our analysis. The results presented in this paper allow a rapid performance evaluation of TCP traffic circulating in the actual IP networks.

The Effects of Different Congestion Management Algorithms over Voip Performance

This paper presents one of the features of DS (Differentiated Services) architecture, namely the queuing or congestion management. Packets can be placed into separate buffer queues, on the basis of the DS value. Several forwarding policies can be used to favor high priority packets in different ways. The major reason for queuing is that the router must hold the packet in its memory while the outgoing interface is busy with sending another packet. The main goal is to compare the performance of the following queuing mechanisms using a laboratory environment: FIFO (First-In First-Out), CQ (Custom Queuing), PQ (Priority Queuing), WFQ (Weighted Fair Queuing), CBWFQ (Class Based Weighted Fair Queuing) and LLQ (Low Latency Queuing). The research is empirical and qualitative, the results are useful both in infocommunication and in education.

CONGESTION CONTROL BASED ON SLIDING MODE CONTROL AND SCHEDULING WITH PRIORITIZED QUEUING FOR WIRELESS NETWORKS

The application of sliding mode control in wireless network is used for considering the joint congestion control and scheduling. Incorporating dual decomposition enables the joint congestion control and scheduling problem to be considered separately. The communication among these two sub problems is given by the lagrangian price value. Based on the utility optimization of network the congestion control performance for queues can be improved using sliding mode based congestion controller. Buffers on network devices are managed with various queuing techniques. Properly managed queues can minimize dropped packets and network congestion, as well as improve network performance. Thus, the queuing structure of CBWFQ (Class Based Weighted Fair Queuing) and strict Priority is combined so that the packets are classified into different classes and priorities are given to these classes, where the higher priority are given to delay sensitive packets and are scheduled effectively.

Performance Tuning of Dual-priority Delta Networks through Queuing Scheduling Disciplines

Differentiated Services (DiffServ) and other scheduling strategies are now widespread in the traditional, “best effort” Internet. These Internet Architectures offer Quality of Service (QoS) guarantees for important customers at the same time as supporting less critical applications of lower priority. Strict priority queuing (PQ), weighted round robin (WRR), and class-based weighted fair queuing (CBWFQ) are three common scheduling disciplines for differentiation of services in telecommunication networks. In this paper, a comparative performance study of the above PQ, WRR and CBWFQ queuing scheduling policies applied on a double-buffered, 6-stage Multistage Interconnection Network (MIN) that natively supports a 2-class priority mechanism is presented and analyzed using simulation experiments. We also consider a 10-stage MIN, to validate that the conclusions drawn from the 6-stage MIN apply to MINs of different sizes. The findings of this paper can be used by MIN designers to optimally configure their networks.

Class-based weighted fair queuing scheduling on quad-priority Delta Networks

Contemporary networks support multiple priorities, aiming to differentiate the quality of service (QoS) levels offered to individual traffic classes. Support for multiple priorities necessitates the introduction of a scheduling algorithm, to select each time the next packet to transmit over the data link. Class-based weighted fair queuing (CBWFQ) scheduling and its variations are widely used as a scheduling technique since it is easy to implement and prevent the low-priority queues from starvation, i.e. receiving no service during periods of high-priority traffic. CBWFQ effectively thus offers low-priority queues, the opportunity to transmit packets even though the high-priority queues are not empty. In this paper, we present the modelling and performance evaluation of a single-buffered, four-priority multistage interconnection network (MIN) operating under the CBWFQ scheduling policy. Performance evaluation is conducted through simulation, and the performance metrics obtained can be used by MIN designers to set the appropriate queue weights according to the expected traffic and the desired QoS levels for each priority class, delivering efficient thus systems.

Class-Based Weighted Fair Queuing Scheduling on Dual-Priority Delta Networks

Contemporary networks accommodate handling of multiple priorities, aiming to provide suitable QoS levels to different traffic classes. In the presence of multiple priorities, a scheduling algorithm is employed to select each time the next packet to transmit over the data link. Class-based Weighted Fair Queuing (CBWFQ) scheduling and its variations is widely used as a scheduling technique, since it is easy to implement and prevents the low-priority queues from being completely neglected during periods of high-priority traffic. By using this scheduling, low-priority queues have the opportunity to transmit packets even though the high-priority queues are not empty. In this work, the modeling, analysis and performance evaluation of a single-buffered, dual-priority multistage interconnection network (MIN) operating under the CBWFQ scheduling policy is presented. Performance evaluation is conducted through simulation, and the performance measures obtained can be valuable assets for MIN designers, in order to minimize the overall deployment costs and delivering efficient systems.

Precedence-enabled per-hop behaviour: impact on TCP and UDP flows

The author proposes and analyses an approach to support both precedence and preemption (P&P) and QoS handling in common packet transport infrastructures. Precedence has to do with the relative importance of the information content, whereas preemption has to do with mechanisms to deny lower precedence traffic access to network resources in favour of higher precedence traffic, when necessary. The author's approach to this duality is to enhance active queue management (AQM) techniques to provide P&P capabilities and rely on standard, well-studied QoS schedulers, for example, Weighted Round Robin, Class-Based Weighted Fair Queuing, etc., for handling QoS requirements. The present scheme allows low-order queues (within the context of QoS handling) to plead up to the next higher-order queue for help in alleviating queue congestion under periods of communication link overload. The scheme is referred as the cross-queue-AQM (CQ-ACM) scheme and can be extended to higher numbers of queues and any type of scheduler. Through extensive simulation studies, the performance of CQ-AQM scheme under heavy traffic limits is investigated, where preemption is required. The performance metrics of interest to this analysis are packet delay, packet loss and throughput as a function of the packet QoS class and P-L. Further, two new metrics of merit, Gain and System Efficiency, are defined, which are specific to P&P considerations. The studies concentrated on both flow-controlled and non-flow-controlled traffic, as well as mixed traffic conditions. Simulation results show that the algorithms perform extremely well for all cases studied.

Efficient Integrated Services in an Enterprise Network

Engineering an enterprise to efficiently support integrated voice and data services requires sophisticated queuing disciplines to meet quality of service requirements. This study evaluates tradeoffs with three queuing schemes. Knowing that the choice of queuing discipline affects utilization, we ran a simulation for each of three queuing schemes - first come, first served (FCFS); priority queuing (PQ); and class-based weighted fair queuing (CBWFQ) - evaluating utilization at various bandwidths that would meet QoS requirements. The results showed that, with these three queuing disciplines, voice and data packets can receive the desired QoS.