Results 1  10
of
56
Adaptive Proportional Routing: A Localized QoS Routing Approach
, 2002
"... 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 ..."
Abstract

Cited by 68 (6 self)
 Add to MetaCart
(Show Context)
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.
BandwidthDelay Constrained Path Selection Under Inaccurate State Information
, 2003
"... One of the key issues in any qualityofservice (QoS) routing framework is how to compute a path that satisfies given QoS constraints. In this paper, we focus on the path computation problem subject to the bandwidth and delay constraints. This problem can be easily solved if the exact state informat ..."
Abstract

Cited by 37 (5 self)
 Add to MetaCart
One of the key issues in any qualityofservice (QoS) routing framework is how to compute a path that satisfies given QoS constraints. In this paper, we focus on the path computation problem subject to the bandwidth and delay constraints. This problem can be easily solved if the exact state information is available to the node performing the path computation function. In practice, however, nodes have only imprecise knowledge of the network state. The reliance on outdated information (and treating this information as exact) can significantly degrade the effectiveness of the path selection algorithm. To address this problem, we adopt a probabilistic approach in which the state parameters (available bandwidth and delay) are characterized by random variables. The goal is then to find the mostprobable bandwidthdelayconstrained path (MPBDCP). We provide efficient solutions for the MPBDCP problem by decomposing it into two subproblems: the mostprobable delayconstrained path (MPDCP) problem and the mostprobable bandwidthconstrained path (MPBCP) problem. MPDCP by itself is known to be NPhard, necessitating the use of approximate solutions. By employing the central limit theorem and Lagrange relaxation techniques, we provide two complementary solutions for MPDCP. These solutions are found to be highly efficient, requiring on average a few iterations of Dijkstra’s shortest path algorithm. As for MPBCP, it can be easily transformed into a variant of the shortest path problem. Our solutions for MPDCP and MPBCP are then combined to address the MPBDCP problem by obtaining a set of nearnondominated paths. Decision makers can then select one or more of these paths based on a specific utility function. Extensive simulations are used to demonstrate the efficiency of the proposed algorithmic solutions and, more generally, to contrast the probabilistic path selection approach with the standard thresholdbased triggered approach.
Logically Centralized? State Distribution Tradeoffs in Software Defined Networks
"... Software Defined Networks (SDN) give network designers freedom to refactor the network control plane. One core benefit of SDN is that it enables the network control logic to be designed and operated on a global network view, as though it were a centralized application, rather than a distributed syst ..."
Abstract

Cited by 25 (2 self)
 Add to MetaCart
(Show Context)
Software Defined Networks (SDN) give network designers freedom to refactor the network control plane. One core benefit of SDN is that it enables the network control logic to be designed and operated on a global network view, as though it were a centralized application, rather than a distributed system – logically centralized. Regardless of this abstraction, control plane state and logic must inevitably be physically distributed to achieve responsiveness, reliability, and scalability goals. Consequently, we ask: “How does distributed SDN state impact the performance of a logically centralized control application?” Motivated by this question, we characterize the state exchange points in a distributed SDN control plane and identify two key state distribution tradeoffs. We simulate these exchange points in the context of an existing SDN load balancer application. We evaluate the impact of inconsistent global network view on load balancer performance and compare different state management approaches. Our results suggest that SDN control state inconsistency significantly degrades performance of logically centralized control applications agnostic to the underlying state distribution.
Precomputation for multiconstrained QoS routing in highspeed networks
 in INFOCOM ’03
, 2003
"... Abstract—As one of the most challenging problems of the nextgeneration highspeed networks, qualityof service routing (QoSR) with multiple (k) constraints is an NPcomplete problem. In this paper, we propose a multiconstrained energy functionbased precomputation algorithm, MEFPA. It cares each Q ..."
Abstract

Cited by 22 (3 self)
 Add to MetaCart
(Show Context)
Abstract—As one of the most challenging problems of the nextgeneration highspeed networks, qualityof service routing (QoSR) with multiple (k) constraints is an NPcomplete problem. In this paper, we propose a multiconstrained 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 kdimensional 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 kdimensional QoS metric space. We then introduce our MEFPA for kconstrained 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 nextgeneration highspeed networks. Keywords—QoS routing, precomputation, scalability, linear energy function, performance evaluation I.
The multipath utility maximization problem
 in 41st Annual Allerton Conference on Communication, Control, and Computing
, 2003
"... Abstract In this paper, we study solutions to the multipath utility maximization problem of the type in (1). Optimizations of this type arise naturally in several networking problems such as the multipath flow control problem. When the capacity of the network is large, it can also model the optim ..."
Abstract

Cited by 17 (2 self)
 Add to MetaCart
(Show Context)
Abstract In this paper, we study solutions to the multipath utility maximization problem of the type in (1). Optimizations of this type arise naturally in several networking problems such as the multipath flow control problem. When the capacity of the network is large, it can also model the optimal QoS routing problem and the optimal pricing problem. We present a distributed solution to this problem that can be implemented online. The convergence of the algorithm is established.
Information Collection Services for QoSaware Mobile Applications
 IEEE TRANSACTIONS ON MOBILE COMPUTING
, 2005
"... Efficient resource provisioning that allows for costeffective 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 ..."
Abstract

Cited by 11 (1 self)
 Add to MetaCart
Efficient resource provisioning that allows for costeffective 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 provisioning mechanisms for such dynamic environments must therefore be able to tolerate imprecision in system state while ensuring adequate QoS to the enduser. In this paper, we address the information collection problem for QoSbased 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 coarsegrained user mobility information renders better system performance than using finegrained 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.
Should QoS routing algorithms prefer shortest paths
 IEEE 2003 International Conference on Communications
, 2003
"... Abstract — Multimedia traffic and realtime ecommerce 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 suc ..."
Abstract

Cited by 6 (1 self)
 Add to MetaCart
(Show Context)
Abstract — Multimedia traffic and realtime ecommerce 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 linkstate 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.
An optimization based approach for quality of service routing in highbandwidth networks
 IN IEEE INFOCOM’04, HONG KONG
, 2004
"... In this paper, we propose an optimization based approach for Quality of Service routing in highbandwidth 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 eff ..."
Abstract

Cited by 5 (4 self)
 Add to MetaCart
In this paper, we propose an optimization based approach for Quality of Service routing in highbandwidth 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.
The Stability of Paths in a Dynamic Network
"... Dynamic networks appear in several contexts: QoS routing faces the difficult problem of accurately and efficiently maintaining, distributing and updating network state information, and in wireless ad hoc networking, signal strength fluctuations complicate the choice of stable paths. In this paper we ..."
Abstract

Cited by 3 (0 self)
 Add to MetaCart
Dynamic networks appear in several contexts: QoS routing faces the difficult problem of accurately and efficiently maintaining, distributing and updating network state information, and in wireless ad hoc networking, signal strength fluctuations complicate the choice of stable paths. In this paper we will focus on the stability of paths in a network with dynamically changing link weights. The level of path stability has a direct relation to the number of updates that are necessary to maintain an accurate view of the network state. If a small change in the network state does not affect the shortest path, then such a change need not be distributed throughout the network. We evaluate path stability by adding noise and observing the change in paths.
Computing a Most Probable Delay Constrained Path: NPHardness and Approximation Schemes
"... Abstract — Delay constrained path selection is concerned with finding a sourcetodestination path so that the delay of the path is within a given delay bound. When the network is modeled by a directed graph where the delay of a link is a random variable with a known mean and a known variance, the p ..."
Abstract

Cited by 3 (0 self)
 Add to MetaCart
(Show Context)
Abstract — Delay constrained path selection is concerned with finding a sourcetodestination path so that the delay of the path is within a given delay bound. When the network is modeled by a directed graph where the delay of a link is a random variable with a known mean and a known variance, the problem becomes that of computing a most probable delay constrained path. In this paper, we present a comprehensive theoretical study of this problem. First, we prove that the problem is NPhard. Next, for the case where there exists a sourcetodestination path with a delay mean no more than the given delay bound, we present a fully polynomial time approximation scheme. In other words, for any given constant ɛ such that 0 <ɛ<1, our algorithm computes a path whose probability of satisfying the delay constraint is at least (1 − ɛ) times the probability that the optimal path satisfies the delay constraint, with a time complexity bounded by a polynomial in the number of network nodes and 1/ɛ. Finally, for the case where any sourcetodestination path has a delay mean larger than the given delay bound, we present a simple approximation algorithm with an approximation ratio bounded by the square root of the hopcount of the optimal path. Index Terms — Delay constrained path selection, computational complexity, approximation schemes. 1.