An Analysis of flow-based routing

Since their development in the early 1970\u27s, the underlying function of IP routers has not changed - they still support a best effort delivery method in order to pass frames from source to destination. With the advent of newer, bandwidth intensive Internet-based services and applications, such as video conferencing and telemedicine, many individuals wonder if the current approach to routing is the most practical. The Internet needs to provide quality of service ( QoS ) as predictably as conventional circuit switching networks. Although some QoS capabilities in an isolated environment have been demonstrated, providing end-to-end QoS at a large scale across the Internet remains an unsolved problem [1]. The alternative to the traditional method of IP routing is a concept known as flow-based routing, whereas traffic is sent across the network as part of a common flow, rather than individually inspecting each packet. As part of this thesis, the differences between flow-based routing and the current standard of IP routing will be investigated. There are many benefits to be had from routing based on flows, for both routers and applications. Some research has already been done on specific aspects of flow-based routing, but because the concept is so cutting-edge, resources are scarce. This study delves into the benefits and obstacles of flow-based routing, and analyzes characteristics such as practicality and security, along with the benefits of this model

Quality-of-service provisioning in high speed networks : routing perspectives

The continuous growth in both commercial and public network traffic with various quality-of-service (QoS) requirements is calling for better service than the current Internet\u27s best effort mechanism. One of the challenging issues is to select feasible paths that satisfy the different requirements of various applications. This problem is known as QoS routing. In general, two issues are related to QoS routing: state distribution and routing strategy. Routing strategy is used to find a feasible path that meets the QoS requirements. State distribution addresses the issue of exchanging the state information throughout the network, and can be further divided into two sub-problems: when to update and how to disseminate the state information. In this dissertation, the issue of when to update link state information from the perspective of information theory is addressed. Based on the rate-distortion analysis, an efficient scheme, which outperforms the state of the art in terms of both protocol overhead and accuracy of link state information, is presented. Second, a reliable scheme is proposed so that, when a link is broken, link state information is still reachable to all network nodes as long as the network is connected. Meanwhile, the protocol overhead is low enough to be implemented in real networks. Third, QoS routing is NP-complete. Hence, tackling this problem requires heuristics. A common approach is to convert this problem into a shortest path or k-shortest path problem and solve it by using existing algorithms such as Bellman-Ford and Dijkstra algorithms. However, this approach suffers from either high computational complexity or low success ratio in finding the feasible paths. Hence, a new problem, All Hops k-shortest Path (AHKP), is introduced and investigated. Based on the solution to AHKP, an efficient self-adaptive routing algorithm is presented, which can guarantee in finding feasible paths with fairly low average computational complexity. One of its most distinguished properties is its progressive property, which is very useful in practice: it can self-adaptively minimize its computational complexity without sacrificing its performance. In addition, routing without considering the staleness of link state information may generate a significant percentage of false routing. Our proposed routing algorithm is capable of minimizing the impact of stale link state information without stochastic link state knowledge. Fourth, the computational complexities of existing s-approximation algorithms are linearly proportional to the adopted linear scaling factors. Therefore, two efficient algorithms are proposed for finding the optimal (the smallest) linear scaling factor such that the computational complexities are reduced. Finally, an efficient algorithm is proposed for finding the least hop(s) multiple additive constrained path for the purpose of saving network resources

Integrated mechanisms for QoS and restoration in mesh transport networks

Survivable networks have the capability to survive from the events of network components failures. The resilience mechanisms in these networks protect and restore the impaired communication paths by using spare capacity. On the other hand, Quality of Service (QoS) mechanisms focus on network capabilities that provide the facilities to differentiate network traffic and offer different levels of service to each class of traffic. Traditionally the survivability algorithms were applied at the physical (optical) layer, whereas the QoS mechanisms mainly applied at packet-forwarding level. Recent technological breakthroughs can now facilitate novel forwarding techniques for optical data bursts that make it possible to capture packets at the optical layer. A major challenge in the transfer of these ultrahigh-speed data bursts is to allocate resources according to QoS specifications and to provide spare capacity required to address link failures

Implementación de calidad de servicio vía Multiprotocol Label Switching (MPLS)

Debido la expansión del fenómeno Internet y, consecuentemente, del fenómeno IP, han surgido nuevas formas de tráfico que desafían las premisas básicas del proyecto de redes IP. Estos tráficos, flujos multimedia en tiempo real, no solamente demandan grandes tasas de transmisión sino también imponen exigencias particulares de timing como baja tolerancia a retraso y altas garantías fin-a-fin de entrega al destino. Los diseñadores de redes IP basan su proyecto original en el encaminamiento de paquetes de forma best effort, un enfoque que no distingue explícitamente las necesidades de flujos particulares. Las tentativas de solución de esta aparente dicotomía envuelven muchas tecnologías y filosofías conocidas simplemente como Calidad de Servicio (QoS), que, en una red IP, definen la habilidad de la red compensar características diferentes de tráfico, sin comprometer el throughput medio de la red. Muchos grupos del IETF (Internet Engineering Task Force) están trabajando con diversos enfoques para estandarización de este servicio.Due to the expansion of the Internet phenomenon and consequently of the IP phenomenon, a new breed of traffic has emerged of that form that challenges the fundamental assumptions about the IP design of networks. This traffic, real-time multimedia streams, not only demand higher end-to-end delivery guarantees tan other data. On the other side, IP's developers based its original design on best efforl packet forwarding, an approach that does not distinguish explicitly between the needs of parlicular streams. The attempts at resolution of this apparent dichotomy consist of many technologies and philosophies known as Quality of Service (QoS). In an IP network, QoS defines the ability to compensate for traffic characteristics without compromising average throughput. Severa/ Internet Engineering task Force Groups are working on standardization approaches for IPbased technologies

Providing quality of service to internet applications using multiprotocol label switching

The growth of the Internet and the range of applications it now supports has created a need for improved traffic engineering techniques. One protocol which shows promise in this regard is Multiprotocol Label Switching (MPLS). MPLS inherits a mix of attributes from earlier protocols such as IP and ATM, and potentially combines the simplicity of IP and the Quality of Service (QoS) capabilities of ATM. MPLS is now a mature standard widely deployed in the Internet. This thesis concerns the development of new mechanisms that can further extend the MPLS capabilities for traffic engineering. Web service remains a key application in today's Internet. The traffic demands at popular Web-sites and the requirements of redundancy and reliability can only be met by using multiple Web servers. A new solution to Web server load balancing based on MPLS is presented in this thesis. This solution features a novel Web switching architecture featuring switching at layer two. An extended solution for providing differentiated Web services is also proposed . It has been implemented in a soft MPLS router using the Linux operating system. The performance of soft routers is significantly affected by the packet processing time. An MPLS-based framework to increase the average packet size and consequently reduce the traffic frame-rate is described in the thesis. This has been implemented in a Linux-based soft router and its performance evaluated experimentally. As transmission rates continue to rise, such aggregation techniques will be needed if packet processing time is not to become a bottleneck. The switching technology at the core of tomorrow's Internet, featuring GMPLS and optical switching using , perhaps, optical burst switching technology, will not work efficiently with short packets. A new class of scheduling algorithms is also described, intended for deployment in MPLS networks. Their operation is based on an analogy with the workings of the human heart. This class of algorithms achieves the optimal fairness for packet based schedulers and has low hardware complexity. It can be combined with the packet aggregation mechanism above to provide an effective interface between the edges of tomorrow's Internet and its high-speed core

Localised Routing Algorithms with Quality of Service Constraints. Development and performance evaluation by simulation of new localised Quality of Service routing algorithms for communication networks using residual bandwidth and mean end-to-end delay as metrics.

School of Computing, Informatics and MediaLocalised QoS routing is a relatively new, alternative and viable approach to solve the problems of traditional QoS routing algorithms which use global state information resulting in the imposition of a large communication overhead and route flapping. They make use of a localised view of the network QoS state in source nodes to select paths and route flows to destination nodes. Proportional Sticky Routing (PSR) and Credit Based Routing (CBR) have been proposed as localised QoS routing schemes and these can offer comparable performances. However, since network state information for a specific path is only updated when the path is used, PSR and CBR operate with decision criteria that are often stale for paths that are used infrequently. The aim of this thesis is to focus on localised QoS routing and contribute to enhancing the scalability of QoS routing algorithms. In this thesis we have developed three new localised QoS routing schemes which are called Score Based QoS Routing (SBR), Bandwidth Based QoS Routing (BBR) and Delay Based Routing (DBR). In some of these schemes, the path setup procedure is distributed and uses the current network state to make decisions thus avoiding problems of staleness. The methods also avoid any complicated calculations. Both SBR and BBR use bandwidth as the QoS metric and mean delay is used as the QoS metric in DBR. Extensive simulations are applied to compare the performance of our proposed algorithms with CBR and the global Dijkstra¿s algorithm for different update intervals of link state, different network topologies and using different flow arrival distributions under a wide range of traffic loads. It is demonstrated by simulation that the three proposed algorithms offer a superior performance under comparable conditions to the other localised and global algorithms

Localized Quality of Service Routing Algorithms for Communication Networks. The Development and Performance Evaluation of Some New Localized Approaches to Providing Quality of Service Routing in Flat and Hierarchical Topologies for Computer Networks.

Quality of Service (QoS) routing considered as one of the major components of the QoS framework in communication networks. The concept of QoS routing has emerged from the fact that routers direct traffic from source to destination, depending on data types, network constraints and requirements to achieve network performance efficiency. It has been introduced to administer, monitor and improve the performance of computer networks. Many QoS routing algorithms are used to maximize network performance by balancing traffic distributed over multiple paths. Its major components include bandwidth, delay, jitter, cost, and loss probability in order to measure the end users¿ requirements, optimize network resource usage and balance traffic load. The majority of existing QoS algorithms require the maintenance of the global network state information and use it to make routing decisions. The global QoS network state needs to be exchanged periodically among routers since the efficiency of a routing algorithm depends on the accuracy of link-state information. However, most of QoS routing algorithms suffer from scalability problems, because of the high communication overhead and the high computation effort associated with marinating and distributing the global state information to each node in the network.The goal of this thesis is to contribute to enhancing the scalability of QoS routing algorithms. Motivated by this, the thesis is focused on localized QoS routing that is proposed to achieve QoS guarantees and overcome the problems of using global network state information such as high communication overhead caused by frequent state information updates, inaccuracy of link-state information for large QoS state update intervals and the route oscillating due to the view of state information. Using such an approach, the source node makes its own routing decisions based on the information that is local to each node in the path. Localized QoS routing does not need the global network state to be exchanged among network nodes because it infers the network state and avoids all the problems associated with it, like high communication and processing overheads and oscillating behaviour. In localized QoS routing each source node is required to first determine a set of candidate paths to each possible destination. In this thesis we have developed localized QoS routing algorithms that select a path based on its quality to satisfy the connection requirements. In the first part of the thesis a localized routing algorithm has been developed that relies on the average residual bandwidth that each path can support to make routing decisions. In the second part of the thesis, we have developed a localized delay-based QoS routing (DBR) algorithm which relies on a delay constraint that each path satisfies to make routing decisions. We also modify credit-based routing (CBR) so that this uses delay instead of bandwidth. Finally, we have developed a localized QoS routing algorithm for routing in two levels of a hierarchal network and this relies on residual bandwidth to make routing decisions in a hierarchical network like the internet. We have compared the performance of the proposed localized routing algorithms with other localized and global QoS routing algorithms under different ranges of workloads, system parameters and network topologies. Simulation results have indicated that the proposed algorithms indeed outperform algorithms that use the basics of schemes that currently operate on the internet, even for a small update interval of link state. The proposed algorithms have also reduced the routing overhead significantly and utilize network resources efficiently