Just Queuing: Policy-Based Scheduling Mechanism for Packet Switching Networks

The pervasiveness of the Internet and its applications lead to the potential increment of the users’ demands for more services with economical prices. The diversity of Internet traffic requires some classification and prioritisation since some traffic deserve much attention with less delay and loss compared to others. Current scheduling mechanisms are exposed to the trade-off between three major properties namely fairness, complexity and protection. Therefore, the question remains about how to improve the fairness and protection with less complex implementation. This research is designed to enhance scheduling mechanism by providing sustainability to the fairness and protection properties with simplicity in implementation; and hence higher service quality particularly for real-time applications. Extra elements are applied to the main fairness equation to improve the fairness property. This research adopts the restricted charge policy which imposes the protection of normal user. In terms of the complexity property, genetic algorithm has an advantage in holding the fitness score of the queue in separate storage space which potentially minimises the complexity of the algorithm. The integrity between conceptual, analytical and experimental approach verifies the efficiency of the proposed mechanism. The proposed mechanism is validated by using the emulation and the validation experiments involve real router flow data. The results of the evaluation showed fair bandwidth distribution similar to the popular Weighted Fair Queuing (WFQ) mechanism. Furthermore, better protection was exhibited in the results compared with the WFQ and two other scheduling mechanisms. The complexity of the proposed mechanism reached O(log(n)) which is considered as potentially low. Furthermore, this mechanism is limited to the wired networks and hence future works could improve the mechanism to be adopted in mobile ad-hoc networks or any other wireless networks. Moreover, more improvements could be applied to the proposed mechanism to enhance its deployment in the virtual circuits switching network such as the asynchronous transfer mode networks

Deadline-ordered parallel iterative matching with QoS guarantee.

by Lui Hung Ngai.Thesis (M.Phil.)--Chinese University of Hong Kong, 2000.Includes bibliographical references (leaves 56-[59]).Abstracts in English and Chinese.Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Thesis Overview --- p.3Chapter 2 --- Background & Related work --- p.4Chapter 2.1 --- Scheduling problem in ATM switch --- p.4Chapter 2.2 --- Traffic Scheduling in output-buffered switch --- p.5Chapter 2.3 --- Traffic Scheduling in Input buffered Switch --- p.16Chapter 3 --- Deadline-ordered Parallel Iterative Matching (DLPIM) --- p.22Chapter 3.1 --- Introduction --- p.22Chapter 3.2 --- Switch model --- p.23Chapter 3.3 --- Deadline-ordered Parallel Iterative Matching (DLPIM) --- p.24Chapter 3.3.1 --- Motivation --- p.24Chapter 3.3.2 --- Algorithm --- p.26Chapter 3.3.3 --- An example of DLPIM --- p.28Chapter 3.4 --- Simulation --- p.30Chapter 4 --- DLPIM with static scheduling algorithm --- p.41Chapter 4.1 --- Introduction --- p.41Chapter 4.2 --- Static scheduling algorithm --- p.42Chapter 4.3 --- DLPIM with static scheduling algorithm --- p.48Chapter 4.4 --- An example of DLPIM with static scheduling algorithm --- p.50Chapter 5 --- Conclusion --- p.54Bibliography --- p.5

Performance Analysis of QoS in PMP Mode WiMax Networks

IEEE 802.16 standard supports two different topologies: point to multipoint (PMP) and Mesh. In this paper, a QoS mechanism for point to multipoint of IEEE 802.16 and BS scheduler for PMP Mode is proposed. This paper also describes quality of service over WiMAX networks. Average WiMAX delay, Average WiMAX load and Average WiMAX throughput at base station is analyzed and compared by applying different scheduler at Base station and at fixed nodes

A survey on the chronological evolution of timestamp schedulers in packet switching networks

The interest in solving the issue of congestion or flow control in network established from the first discovery and increase popularity of the Internet in 1967 or earlier. As the use of the network deployed and the popularity increase, the issue grows and the demand for an optimal or tentative solution becomes obvious. Since that time there has been an intensive effort from the scholars and researchers to solve the congestion control problem. The problem get worse by the engagement of novel traffic with different characteristics for application called realtime applications such as video and voice applications. Another cause of this demand is the user himself. The attempt in solving the congestion problem in network layer was popular in 90’s.This article will demonstrate chronologically how the attempts toward timestamp based scheduling in the packet-switch network have been evolved.Furthermore, the benefit and the drawbacks of using a mechanism will be presented. Also, a brief explanation of the mathematical, conceptual or implementation issue of a mechanism is given. The key success of the scheduler in the market will be highlighted. This paper will stimulate the research thinking to identify the importance and the ability of scheduling in routers to enhance quality of service (QoS) for real time application over other solution in several layers. In addition it will assist the researcher to distinguish the key failure of other proposed mechanisms which have not been implemented in real routers

On scheduling input queued cell switches

Output-queued switching, though is able to offer high throughput, guaranteed delay and fairness, lacks scalability owing to the speed up problem. Input-queued switching, on the other hand, is scalable, and is thus becoming an attractive alternative. This dissertation presents three approaches toward resolving the major problem encountered in input-queued switching that has prohibited the provision of quality of service guarantees. First, we proposed a maximum size matching based algorithm, referred to as min-max fair input queueing (MFIQ), which minimizes the additional delay caused by back pressure, and at the same time provides fair service among competing sessions. Like any maximum size matching algorithm, MFIQ performs well for uniform traffic, in which the destinations of the incoming cells are uniformly distributed over all the outputs, but is not stable for non-uniform traffic. Subse-quently, we proposed two maximum weight matching based algorithms, longest normalized queue first (LNQF) and earliest due date first matching (EDDFM), which are stable for both uniform and non-uniform traffic. LNQF provides fairer service than longest queue first (LQF) and better traffic shaping than oldest cell first (OCF), and EDDEM has lower probability of delay overdue than LQF, LNQF, and OCF. Our third approach, referred to as store-sort-and-forward (SSF), is a frame based scheduling algorithm. SSF is proved to be able to achieve strict sense 100% throughput, and provide bounded delay and delay jitter for input-queued switches if the traffic conforms to the (r, T) model

A cross-layer architecture to improve mobile host rate performance and to solve unfairness problem in WLANs

The evolution of the Internet has been mainly promoted in recent years by the emergence and pro- liferation of wireless access networks towards a global ambient and pervasive network accessed from mobile devices. These new access networks have introduced new MAC layers independently of the legacy "wire- oriented" protocols that are still at the heart of the pro- tocol stacks of the end systems. This principle of isola- tion and independence between layers advocated by the OSI model has its drawbacks of maladjustment between new access methods and higher-level protocols built on the assumption of a wired Internet. In this paper, we introduce and deliver solutions for several pathologi- cal communication behaviors resulting from the malad- justment between WLAN MAC and higher layer stan- dard protocols such as TCP/IP and UDP/IP. Specially, based on an efficient analytical model for WLANs band- width estimation, we address in this paper the two fol- lowing issues: 1) Performance degradation due to the lack of flow control between the MAC and upper layer resulting in potential MAC buffer overflow; 2) Unfair bandwidth share issues between various type of flows. We show how these syndromes can be efficiently solved from neutral "cross layer" interactions which entail no changes in the considered protocols and standards