A route pre-computation algorithm for integrated services networks

We provide an algorithm for computing best paths on a graph where edges have a multidimensional cost, one dimension representing delay, the others representing available capacity. Best paths are those which guarantee maximum capacity with least possible delay. The complexity of the algorithm is of the order of O(V3) in the bidimensional case, for a graph withV vertices. The results can be used for routing connections with guaranteed capacity in a communication network

Обзор технологических и теоретических решений в области маршрутизации на основе качества обслуживания

Проведен обзор решений задач маршру-тизации на основе качества обслуживания, включаю-щий как протокольные варианты, так и теоретиче-ские решения, которые еще не получили технологиче-ской реализации. Обзор охватывает комбинаторные методы маршрутизации, а также потоковые модели и методы формализации и решения маршрутных задач.Under rising requirements for telecommunication network role of routing increases, because routing is an ef-fective tool to ensure the specified end-to end quality of service (QoS). Nowadays the routing is transformed into QoS-based rout-ing which focuses on the searching one or more paths for delivering packets where all described in the SLA requirements for quali-ty of service must be satisfied. A set of technological and theoretical solutions is developed for solving QoS-based routing problem. About it several concepts deserves attention among which source routing, precomputed routing, route server concept. From theo-retical point of view QoS-based routing problem can be solved by using graph theory approach or flow-based mathematical model of network. The graph theory approach is based on structure only and doesn’t take into account flow properties of transmitted traffic. As a result it doesn’t allow allocating network resources between different traffics and concordance between routing, accesses, queuing, and reservation. As a rule a flow-based approach solves QoS-based routing problem as mathematical programming prob-lem with QoS-constrains. For example, it can be tensor constrains. The article contains possible lines of development of QoS-based routing that include conversion to dynamical metrics and dynamical models with QoS-constrains, not only load balancing but quality balancing, concordance between routing and another traffic control tasks

Обзор технологических и теоретических решений в области маршрутизации на основе качества обслуживания

Проведен обзор решений задач маршру-тизации на основе качества обслуживания, включаю-щий как протокольные варианты, так и теоретиче-ские решения, которые еще не получили технологиче-ской реализации. Обзор охватывает комбинаторные методы маршрутизации, а также потоковые модели и методы формализации и решения маршрутных задач.Under rising requirements for telecommunication network role of routing increases, because routing is an ef-fective tool to ensure the specified end-to end quality of service (QoS). Nowadays the routing is transformed into QoS-based rout-ing which focuses on the searching one or more paths for delivering packets where all described in the SLA requirements for quali-ty of service must be satisfied. A set of technological and theoretical solutions is developed for solving QoS-based routing problem. About it several concepts deserves attention among which source routing, precomputed routing, route server concept. From theo-retical point of view QoS-based routing problem can be solved by using graph theory approach or flow-based mathematical model of network. The graph theory approach is based on structure only and doesn’t take into account flow properties of transmitted traffic. As a result it doesn’t allow allocating network resources between different traffics and concordance between routing, accesses, queuing, and reservation. As a rule a flow-based approach solves QoS-based routing problem as mathematical programming prob-lem with QoS-constrains. For example, it can be tensor constrains. The article contains possible lines of development of QoS-based routing that include conversion to dynamical metrics and dynamical models with QoS-constrains, not only load balancing but quality balancing, concordance between routing and another traffic control tasks

A new QoS Routing Architecture in NGI

After a thorough understanding of the relevant research knowledge and the key theory of NGN, I describe the research objectives and the recent development of the QoS routing in this thesis. QoS routing is regarded as the key part in the problem of the next generation of integrated-service network. A new routing algorithm is put forward in this thesis, which is better than OSPF in some aspects. As for the experiment, NS2 is chosen as the simulation environment, and some other experimental results are also included to manifest its strongpoint. The development and requirement of NGN is described in Chapter One; The definition and types of routing and the basic theories of QoS routing are described in Chapter Two; The development and research method of QoS are focused in Chapter Three. The new routing algorithm and simulation is proposed in Chapter Four

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

New quality of service routing algorithms based on local state information. The development and performance evaluation of new bandwidth-constrained and delay-constrained quality of service routing algorithms based on localized routing strategies.

The exponential growth of Internet applications has created new challenges for the control and administration of large-scale networks, which consist of heterogeneous elements under dynamically changing traffic conditions. These emerging applications need guaranteed service levels, beyond those supported by best-effort networks, to deliver the intended services to the end user. Several models have been proposed for a Quality of Service (QoS) framework that can provide the means to transport these services. It is desirable to find efficient routing strategies that can meet the strict routing requirements of these applications. QoS routing is considered as one of the major components of the QoS framework in communication networks. In QoS routing, paths are selected based upon the knowledge of resource availability at network nodes and the QoS requirements of traffic. Several QoS routing schemes have been proposed that differ in the way they gather information about the network state and the way they select paths based on this information. The biggest downside of current QoS routing schemes is the frequent maintenance and distribution of global state information across the network, which imposes huge communication and processing overheads. Consequently, scalability is a major issue in designing efficient QoS routing algorithms, due to the high costs of the associated overheads. Moreover, inaccuracy and staleness of global state information is another problem that is caused by relatively long update intervals, which can significantly deteriorate routing performance. Localized QoS routing, where source nodes take routing decisions based solely on statistics collected locally, was proposed relatively recently as a viable alternative to global QoS routing. It has shown promising results in achieving good routing performance, while at the same time eliminating many scalability related problems. In localized QoS routing each source¿destination pair needs to determine a set of candidate paths from which a path will be selected to route incoming flows. The goal of this thesis is to enhance the scalability of QoS routing by investigating and developing new models and algorithms based on the localized QoS routing approach. For this thesis, we have extensively studied the localized QoS routing approach and demonstrated that it can achieve a higher routing performance with lower overheads than global QoS routing schemes. Existing localized routing algorithms, Proportional Sticky Routing (PSR) and Credit-Based Routing (CBR), use the blocking probability of candidate paths as the criterion for selecting routing paths based on either flow proportions or a crediting mechanism, respectively. Routing based on the blocking probability of candidate paths may not always reflect the most accurate state of the network. This has motivated the search for alternative localized routing algorithms and to this end we have made the following contributions. First, three localized bandwidth-constrained QoS routing algorithms have been proposed, two are based on a source routing strategy and the third is based on a distributed routing strategy. All algorithms utilize the quality of links rather than the quality of paths in order to make routing decisions. Second, a dynamic precautionary mechanism was used with the proposed algorithms to prevent candidate paths from reaching critical quality levels. Third, a localized delay-constrained QoS routing algorithm was proposed to provide routing with an end-to-end delay guarantee. We compared the performance of the proposed localized QoS routing algorithms with other localized and global QoS routing algorithms under different network topologies and different traffic conditions. Simulation results show that the proposed algorithms outperform the other algorithms in terms of routing performance, resource balancing and have superior computational complexity and scalability features.Umm AlQura University, Saudi Arabi