Quality Of Service Enhancement In Ip Based Networks Using Diffserv

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2003Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2003Bu çalışmada, Diffserv mimarisi ile internet üzerinde servis kalitesi sağlama tartışılmıştır. Son on yılda IP tabanlı internette servis kalitesi sağlanamıyordu. İnternette bugün sağlanabilen tek servis ‘Best Effort (BE)’ adı verilen servistir. Yani, ağ, herhangi bir paketi hedefine ulaştırırken mümkün olan en verimli yolu kullanır ancak herhangi bir garanti ya da kaynak ayırımı yapmaz. Başka bir deyişle, trafik mümkün olduğu kadar hızlı ve herhangi bir zaman sınırı ya da miktar açısından garanti verilmeden işlenir. İnternetin ticari bir yapıya bürünmesiyle ‘Servis Kalitesi’ sağlanma ihtiyacı daha da artmıştır. Bu ihtiyaç farklı mimarilerin doğmasına yol açmıştır: IntServ ve DiffServ olmak üzere.Tez çalışmasında DiffServ mimarisi problem ve avantajlarıyla ele alınmıştır. Son bölümde ise NS2 ağ simulasyon yazılımı kullanılarak DiffServ implementasyonları yapılmış sonuçları karşılaştırmalı olarak verilmiştir.In this study improving Quality of Service (QoS) on the Internet with DiffServ architecture is discussed. Within the past decade, it is certainly not support for Quality of Service (QoS) over the IP-based ubiquitous Internet. The Internet as it stands today only support one service class called -Best-Effort (BE) Service. The network would make an earnest attempt to deliver packets to their destinations but with no guarantees and/or special resources allocated for any of the packets. With another words, traffic is processed as quickly as possible but there is no guarantee as to timeliness or actual delivery or even how much can be delivered (i.e. throughput). With the rapid transformation of the Internet into a commercial infrastructure, demands for Quality of Service (QoS) have rapidly developed. This need was resulted to different architectures: IntServ and DiffServ. In the study some DiffServ implementations are discussed with their problems and gains. At the last section with using NS2 simulation programming language some DiffServ implementations are given with the compared results.Yüksek LisansM.Sc

The Squatting and Kicking strategies for self-provisioned, bandwidth resource sharing in multiclass networks

English: This article proposes a self-provisioned, Squatting and Kicking bandwidth resource sharing strategy for multiclass networks where differentiated services are not natively built. Moreover, this article provides a summary of the bandwidth constraints models and shows how the squatting and kicking strategies can be adapted to be the basis for a new bandwidth constraint model, which widens the range of techniques available to operators for bandwidth resource management in multiclass networks.Castellano: Este artículo propone unas estrategias para compartir ancho de banda en redes multi-clase de manera auto-gestionada, donde los servicios diferenciados no se soportan de manera nativa. Además, se provee una comparación de los modelos de ancho de banda limitado y cómo las estrategias "squat" y "kick" se pueden constituir como nuevo modelo. Dicho model ampliará el número de técnicas que los operadores tienen disponibles para la gestión de tráfico en redes multi-clase.Català: Aquest article proposa unes estratègies per a compartir l'amplada de banda en xarxes multi-classe de manera auto-gestionada, a on els serveis diferenciats no se suporten de manera nadiua. A més a més, se proveeix una comparació dels models d'amplada de banda limitat i com les estratègies "squat" i "kick" es poden constituir com a nou model. Aquest nou model ampliarà el nombre de tècniques de que disposen els operadors de xarxes multi-classe per a la gestió del tràfic

A traffic engineering system for DiffServ/MPLS networks

This thesis presents an approach to traffic engineering that uses DiffServ and MPLS technologies to provide QoS guarantees over an IP network. The specific problem described here is how best to route traffic within the network such that the demands can be carried with the requisite QoS while balancing the load on the network. A traffic engineering algorithm that determines QoS guaranteed label-switched paths (LSPs) between specified ingress-egress pairs is proposed and a system that uses such an algorithm is outlined. The algorithm generates a solution for the QoS routing problem of finding a path with a number of constraints (delay, jitter, loss) while trying to make best of resource utilisation. The key component of the system is a central resource manager responsible for monitoring and managing resources within the network and making all decisions to route traffic according to QoS requirements. The algorithm for determining QoS-constrained routes is based on the notion of effective bandwidth and cost functions for load balancing. The network simulation of the proposed system is presented here and simulation results are discussed

IP-based virtual private networks and proportional quality of service differentiation

IP-based virtual private networks (VPNs) have the potential of delivering cost-effective, secure, and private network-like services. Having surveyed current enabling techniques, an overall picture of IP VPN implementations is presented. In order to provision the equivalent quality of service (QoS) of legacy connection-oriented layer 2 VPNs (e.g., Frame Relay and ATM), IP VPNs have to overcome the intrinsically best effort characteristics of the Internet. Subsequently, a hierarchical QoS guarantee framework for IP VPNs is proposed, stitching together development progresses from recent research and engineering work. To differentiate IP VPN QoS, the proportional QoS differentiation model, whose QoS specification granularity compromises that of IntServ and Diffserv, emerges as a potential solution. The investigation of its claimed capability of providing the predictable and controllable QoS differentiation is then conducted. With respect to the loss rate differentiation, the packet shortage phenomenon shown in two classical proportional loss rate (PLR) dropping schemes is studied. On the pursuit of a feasible solution, the potential of compromising the system resource, that is, the buffer, is ruled out; instead, an enhanced debt-aware mechanism is suggested to relieve the negative effects of packet shortage. Simulation results show that debt-aware partially curbs the biased loss rate ratios, and improves the queueing delay performance as well. With respect to the delay differentiation, the dynamic behavior of the average delay difference between successive classes is first analyzed, aiming to gain insights of system dynamics. Then, two classical delay differentiation mechanisms, that is,proportional average delay (PAD) and waiting time priority (WTP), are simulated and discussed. Based on observations on their differentiation performances over both short and long time periods, a combined delay differentiation (CDD) scheme is introduced. Simulations are utilized to validate this method. Both loss and delay differentiations are based on a series of differentiation parameters. Though previous work on the selection of delay differentiation parameters has been presented, that of loss differentiation parameters mostly relied on network operators\u27 experience. A quantitative guideline, based on the principles of queueing and optimization, is then proposed to compute loss differentiation parameters. Aside from analysis, the new approach is substantiated by numerical results

QoS provisioning in multimedia streaming

Multimedia consists of voice, video, and data. Sample applications include video conferencing, video on demand, distance learning, distributed games, and movies on demand. Providing Quality of Service (QoS) for multimedia streaming has been a difficult and challenging problem. When multimedia traffic is transported over a network, video traffic, though usually compressed/encoded for bandwidth reduction, still consumes most of the bandwidth. In addition, compressed video streams typically exhibit highly variable bit rates as well as long range dependence properties, thus exacerbating the challenge in meeting the stringent QoS requirements of multimedia streaming with high network utilization. Dynamic bandwidth allocation in which video traffic prediction can play an important role is thus needed. Prediction of the variation of the I frame size using Least Mean Square (LMS) is first proposed. Owing to a smoother sequence, better prediction has been achieved as compared to the composite MPEG video traffic prediction scheme. One problem with this LMS algorithm is its slow convergence. In Variable Bit Rate (VBR) videos characterized by frequent scene changes, the LMS algorithm may result in an extended period of intractability, and thus may experience excessive cell loss during scene changes. A fast convergent non-linear predictor called Variable Step-size Algorithm (VSA) is subsequently proposed to overcome this drawback. The VSA algorithm not only incurs small prediction errors but more importantly achieves fast convergence. It tracks scene changes better than LMS. Bandwidth is then assigned based on the predicted I frame size which is usually the largest in a Group of Picture (GOP). Hence, the Cell Loss Ratio (CLR) can be kept small. By reserving bandwidth at least equal to the predicted one, only prediction errors need to be buffered. Since the prediction error was demonstrated to resemble white noise or exhibits at most short term memory, smaller buffers, less delay, and higher bandwidth utilization can be achieved. In order to further improve network bandwidth utilization, a QoS guaranteed on-line bandwidth allocation is proposed. This method allocates the bandwidth based on the predicted GOP and required QoS. Simulations and analytical results demonstrate that this scheme provides guaranteed delay and achieves higher bandwidth utilization. Network traffic is generally accepted to be self similar. Aggregating self similar traffic can actually intensify rather than diminish burstiness. Thus, traffic prediction plays an important role in network management. Least Mean Kurtosis (LMK), which uses the negated kurtosis of the error signal as the cost function, is proposed to predict the self similar traffic. Simulation results show that the prediction performance is improved greatly as compared to the LMS algorithm. Thus, it can be used to effectively predict the real time network traffic. The Differentiated Service (DiffServ) model is a less complex and more scalable solution for providing QoS to IP as compared to the Integrated Service (IntServ) model. We propose to transport MPEG frames through various service classes of DiffServ according to the MPEG video characteristics. Performance analysis and simulation results show that our proposed approach can not only guarantee QoS but can also achieve high bandwidth utilization. As the end video quality is determined not only by the network QoS but also by the encoded video quality, we consider video quality from these two aspects and further propose to transport spatial scalable encoded videos over DiffServ. Performance analysis and simulation results show that this can provision QoS guarantees. The dropping policy we propose at the egress router can reduce the traffic load as well as the risk of congestion in other domains

Investigating Basic Quality of Service Design Possibilities for Regis University Academic Research Network Edge Routers

The Regis University Academic Research Network (ARNe) had network resources, such as VoIP, that required preservation their ability to receive near real-time forwarding treatment across the network. Quality of Service (QoS) design ideas were examined from four actual implementations described in research cases. Additionally, research involving surveys from Cisco certified professionals was examined, and Cisco technical literature was examined. Case study methodology, involving the study of multiple cases, was the primary tactic utilized in this research. Examination and triangulation of data from the research indicated that ARNe would benefit from moving forward with a basic QoS design and implementation, integrating concepts identified in the data. Additionally, data supported that a basic QoS design and implementation on ARNe would provide Computer Science and Information Science students an opportunity to more fully appreciate QoS through further research and hands-on experience