Most of the QoS routing schemes proposed so far require periodic exchange of QoS state information among routers, imposing both communication overhead on the network and processing overhead on core routers. Furthermore, stale QoS state information causes the performance of these QoS routing schemes to degrade drastically. In order to circumvent these problems, we focus on localized QoS routing schemes where the edge routers make routing decisions using only local information and thus reducing the overhead at core routers. We first describe virtual capacity based routing (vcr), a theoretical scheme based on the notion of virtual capacity of a route. We then propose proportional sticky routing, an easily realizable approximation of vcr and analyze its performance. We demonstrate through extensive simulations that adaptive proportional routing is indeed a viable alternative to the global QoS routing approach.

Abstract—As one of the most challenging problems of the next-generation high-speed networks, quality-of- service routing (QoSR) with multiple (k) constraints is an NP-complete problem. In this paper, we propose a multi-constrained energy functionbased precomputation algorithm, MEFPA. It cares each QoS k −1 weight to b degrees, and computes a number (B = C b+ k −2) of coefficient vectors uniformly distributed in the k-dimensional QoS metric space to construct B linear energy functions. Using each LEF, it then converts k QoS constraints to a single energy value. At last, it uses Dijkstra's algorithm to create B least energy trees, based on which the QoS routing table is created. We first analyze the performance of energy functions with k constraints, and give the method to determine the feasible and unfeasible areas for QoS requests in the k-dimensional QoS metric space. We then introduce our MEFPA for k-constrained routing with the computation complexity of O(B(m+n+nlogn)). Extensive simulations show that, with few coefficient vectors, this algorithm performs well in both absolute performance and competitive performance. In conclusion, for its high scalability, high performance and simplicity, MEFPA is a promising QoSR algorithm in the next-generation high-speed networks. Keywords—QoS routing, precomputation, scalability, linear energy function, performance evaluation I.

Efficient resource provisioning that allows for cost-effective enforcement of application QoS relies on accurate system state information. However, maintaining accurate information about available system resources is complex and expensive especially in mobile environments where system conditions are highly dynamic. Resource provision-ing mechanisms for such dynamic environments must therefore be able to tolerate imprecision in system state while ensuring adequate QoS to the end-user. In this paper, we address the information collection problem for QoS-based services in mobile environments. Specifically, we propose a family of information collection policies that vary in the granularity at which system state information is represented and maintained. We empirically evaluate the impact of these policies on the performance of diverse resource provisioning strategies. We generally observe that resource provisioning benefits significantly from the customized information collection mechanisms that take advantage of user mobility information. Furthermore, our performance results indicate that effective utilization of coarse-grained user mobility information renders better system performance than using fine-grained user mobility information. Using results from our empirical studies, we derive a set of rules that supports seamless integration of information collection and resource provisioning mechanisms for mobile environments. These results have been incorporated into an integrated middleware framework AutoSeC (Automatic Service Composition) to provide support for dynamic service brokering that ensures effective utilization of system resources over wireless networks.

Abstract — Multimedia traffic and real-time e-commerce applications can experience quality degradation in traditional networks such as the Internet. These difficulties can be overcome in networks which feature dynamically set up paths with bandwidth and delay guarantees. The problem of selecting such constrained paths is the task of Quality of Service (QoS) routing. This paper considers link-state routing, and the choice of cost metric used to implement QoS routing. There are two schools of thought regarding the choice of link cost. It is commonly assumed that QoS routing algorithms should limit hop count so as to conserve resources for future connections. Others advocate load balancing mechanisms so as to increase overall network utilisation. This paper investigates which of these approaches gives the better performance. We show that there is no one general answer to this question. We also point out the dangers of drawing general conclusions about routing algorithm performance based on the study of only a limited set of network topologies. I.

Abstract — In this paper, we propose an optimization based approach for Quality of Service routing in high-bandwidth networks. We view a network that employs QoS routing as an entity that distributively optimizes some global utility function. By solving the optimization problem, the network is driven to an efficient operating point. In earlier work, it has been shown that when the capacity of the network is large, this optimization takes on a simple form, and once the solution to this optimization problem is found, simple proportional QoS routing schemes will suffice. However, this optimization problem requires global information. We develop a distributed and adaptive algorithm that can efficiently solve the optimization online. Compared with existing QoS routing schemes, the proposed optimization based approach has the following advantages: (1) The computation and communication overhead can be greatly reduced without sacrificing performance; (2) The operating characteristics of the network can be analytically studied; and (3) The desired operating point can be tuned by choosing appropriate utility functions. I.

Traffic engineering broadly relates to optimization of the operational performance of a network. This survey discusses techniques like multi-path routing, traffic splitting, constraint-based routing, path-protection etc. that are used for traffic engineering in contemporary Internet Service Provider (ISP) networks. These techniques can be classified under two broad classes, connectionless and connection-oriented, that dominate the current debate on next-generation routing and traffic engineering in IP networks. The connectionless approach evolves current distance-vector and link-state algorithms, or influences routing metrics. The connection-oriented approach uses signaling and is being used by techniques like Multi Protocol Label Switching (MPLS). Connection-oriented techniques offer a convenient way to monitor, allocate, reroute, and protect resources for a given traffic on an explicit and flexible basis. This survey will examine the core problems, discuss solutions in both connectionless and signaled approach, and point to topics for research and advanced development.

To meet the diverse quality-of-service (QoS) requirements of emerging multimedia applications, communication networks should provide end-to-end QoS guarantees. QoS routing is the first step towards this goal. The route computing overhead caused by on-demand calculation of QoS routes, especially in large networks with heavy traffic, is a concern and can cause scalability problems. This paper addresses this problem by introducing a novel distributed cache architecture. The distributed nature of the proposed cache architecture facilitates its deployment in large networks. To maximize the performance of the distributed cache architecture, cache snooping has been proposed to alleviate the side effects of network states fluctuations on the cached route so that the overall routing performance is significantly improved. Assuming a bandwidth-based QoS model, in performance evaluation of the proposed distributed cache architecture, we use a broad range of realistic network topologies, network traffic conditions, routing protocols, and aggregation techniques to evaluate different aspects of the proposed cache architecture under different conditions. The results confirm that the route caching is quite effective in reduction of route computing overhead. In addition, our results suggest that the cache snooping can significantly increase the overall routing performance, especially in the presence of highly inaccurate network state information.

Multimedia traffic and real-time e-commerce applications can experience quality degradation in traditional networks such as the Internet. These difficulties can be overcome in networks which feature dynamically set up paths with bandwidth and delay guarantees. The problem of selecting such constrained paths is the task of Quality of Service (QoS) routing. Researchers have proposed several ways of implementing QoS routing, preferring either mechanisms which distribute the network load or algorithms which conserve resources. Our previous studies have shown that network connectivity is an important factor when deciding which of these two approaches gives the best performance. In this paper we propose an algorithm, which features both load distribution and resource conservation. It takes a hybrid approach which balances between these two extreme approaches, according to the level of network connectivity. Our simulations indicate that this algorithm offers excellent performance over a wider range of network topologies than existing algorithms. 1.

Abstract — We propose a new delay-constrained minimumhop distributed routing algorithm (DCMH) for unicastrouting. DCMH uses a novel path feasibility prediction (PFP) model that is able to predict the feasibility of a tentative routing path, and employs a crankback facility. It is a hybrid algorithm where it uniquely integrates the use of local-state and the global binary connectivity information maintained at each node to compute routing paths. Simulation results show that average message overhead is modest with good connection success and low nodal storage. Index Terms—distributed algorithm, routing, quality of service, path feasibility prediction I.

So far the Internet has offered only best effort service. All traffic is processed as quickly as possible and no preferences are given to any type of traffic. Today there are more and more applications that need service guarantees in order to function properly. These kinds of applications include for instance IP telephony, video-conference applications or video on-demand services. One important part of the QoS framework is the ability to find the paths that have sufficient resources to support the QoS requirements of a traffic flow. Current Internet routing protocols always forward packets to the shortest path based on hop count. This can cause problems for flows with a need for performance requirements, if the shortest path does not have the resources needed to meet these requirements. Quality of Service routing is a routing scheme that considers the quality of service requirements of a flow when making routing decisions. As opposed to traditional shortest path routing, which only considers the hop count, QoS routing is designed to find feasible paths that satisfy multiple constraints. This thesis is a survey on QoS routing. It presents the most important problems in QoS routing concerning path selection algorithms, cost of QoS routing, and different approaches. Routing problems for cases with one or two metric are formalized as optimization problems, and solutions algorithms are presented. For the