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93
MultiConstrained Optimal Path Selection
, 2001
"... Providing qualityofservice (QoS) guarantees in packet networks gives rise to several challenging issues. One of them is how to determine a feasible path that satisfies a set of constraints while maintaining high utilization of network resources. The latter objective implies the need to impose an a ..."
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Cited by 76 (1 self)
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Providing qualityofservice (QoS) guarantees in packet networks gives rise to several challenging issues. One of them is how to determine a feasible path that satisfies a set of constraints while maintaining high utilization of network resources. The latter objective implies the need to impose an additional optimality requirement on the feasibility problem. This can be done through a primary cost function (e.g., administrative weight, hopcount) according to which the selected feasible path is optimal. In general, multiconstrained path selection, with or without optimization, is an NPcomplete problem that cannot be exactly solved in polynomial time. Heuristics and approximation algorithms with polynomialand pseudopolynomialtime complexities are often used to deal with this problem. However, existing solutions suffer either from excessive computational complexities that cannot be used for online network operation or from low performance. Moreover, they only deal with special cases of the problem (e.g., two constraints without optimization, one constraint with optimization, etc.). For the feasibility problem under multiple constraints, some researchers have recently proposed a nonlinear cost function whose minimization provides a continuous spectrum of solutions ranging from a generalized linear approximation (GLA) to an asymptotically exact solution. In this paper, we propose an efficient heuristic algorithm for the most general form of the problem. We first formalize the theoretical properties of the above nonlinear cost function. We then introduce our heuristic algorithm (H MCOP), which attempts to minimize both the nonlinear cost function (for the feasibility part) and the primary cost function (for the optimality part). We prove that H MCOP guarantees at least t...
Hopbyhop quality of service routing
 COMPUTER NETWORKS
, 2001
"... Based on the selfadaptive multiple constraints routing algorithm (SAMCRA), an improved and exact version of our QoS routing algorithm, the tunable accuracy multiple constraints routing algorithm (TAMCRA) we have investigated QoS routing in a hopbyhop manner because it forms the basis of IP networ ..."
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Cited by 44 (10 self)
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Based on the selfadaptive multiple constraints routing algorithm (SAMCRA), an improved and exact version of our QoS routing algorithm, the tunable accuracy multiple constraints routing algorithm (TAMCRA) we have investigated QoS routing in a hopbyhop manner because it forms the basis of IP networking as e.g. in OSPF. In particular, we studied `hopbyhop destination based only' (HbHDBO) QoS routing that ignores the source and previous path history (as in current IP routing). We demonstrate that an exact QoS algorithm assures the avoidance of routing loops in this HbHDBO setting. However, despite the use of an exact QoS routing algorithm as SAMCRA, the exact solution cannot be guaranteed with HbHDBO routing. Fortunately, large simulation results on various sizes of random graphs show that the overall quality of the HbHDBO QoS routing is remarkably good. Finally, we show that, by using active networking as opposed to current IP routing, exact QoS routing in a hopbyhop way can be guaranteed.
Distributed Partial Information Management (DPIM) Schemes for Survivable Networks  Part I
, 2002
"... This paper describes a novel framework, called Distributed Partial Information Management (or DPIM). It addresses several major challenges in achieving efficient shared path protection under distributed control with only partial information, including (1) how much partial information about existing ..."
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Cited by 40 (5 self)
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This paper describes a novel framework, called Distributed Partial Information Management (or DPIM). It addresses several major challenges in achieving efficient shared path protection under distributed control with only partial information, including (1) how much partial information about existing active and backup paths (or APs and BPs respectively) is maintained and exchanged; (2) how to obtain a good estimate of the bandwidth needed by a candidate BP, called BBW, and subsequently select a pair of AP and BP for a connection establishment request so as to minimize total bandwidth consumption and/or maximize revenues; (3) how to distributively allocate minimal BBW (and deallocate maximal BBW) via distributed signaling; and (4) how to update and subsequently exchange the partial information.
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 ..."
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Cited by 23 (2 self)
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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.
Polynomial Time Approximation Algorithms for MultiConstrained QoS Routing
"... We study the multiconstrained QualityofService (QoS) routing problem where one seeks to find a path from a source to a destination in the presence of K ≥ 2 additive QoS constraints. Specifically we consider an optimization version of the problem called the OMCP problem which is defined as follo ..."
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Cited by 21 (5 self)
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We study the multiconstrained QualityofService (QoS) routing problem where one seeks to find a path from a source to a destination in the presence of K ≥ 2 additive QoS constraints. Specifically we consider an optimization version of the problem called the OMCP problem which is defined as follows. Let G = (V, E) be a directed graph with vertex set V and edge set E, where each edge e ∈ E is associated with K additive weights ωk(e) ≥ 0, 1 ≤ k ≤ K. Given a sourcedestination node pair (s, t) and a constraint vector � W = (W1,..., WK) where each Wk is a positive constant, find an s–t path π such that max2≤k≤K ω k(π) W k is minimized, subject to the constraint that ω1(π) ≤ W1. We present an O(mn log log log n + mn/ɛ) time (1 + ɛ)(K − 1)approximation algorithm and an O(mn log log log n+m ( n ɛ)K−1) time (1 + ɛ)approximation algorithm, for any ɛ> 0, where n = V  and m = E. For the case of K = 2, the OMCP problem is equivalent to the wellknown DCLC problem where we seek a path which has minimum value for one metric and satisfies a constraint on the other metric. When K is equal to 2, both of our approximation algorithms produce an (1 + ɛ)approximation, with a time complexity better than that of the bestknown algorithm designed for the DCLC problem. We then consider the decision version of the OMCP problem, and present an O(m ( n ɛ)K−1) time algorithm which either finds a feasible solution satisfying all the constraints or confirms that there does not exist a sourcedestination path whose first weight is bounded by the first constraint and whose every other weight is bounded by (1 − ɛ) times the corresponding constraint. If there exists an Hhop sourcedestination path whose first weight is bounded by the first constraint and whose every other weight is bounded by (1 − ɛ) times the corresponding constraint, our algorithm finds a feasible path in O(m ( H ɛ)K−1) time. This algorithm improves previously bestknown algorithms that have a time complexity of O((m + n log n)n/ɛ) time for K = 2 and a time complexity of O(mn(n/ɛ) K−1) time for K ≥ 2.
Finding a Path Subject to Many Additive QoS Constraints
"... A fundamental problem in QualityofService (QoS) routing is to find a path between a sourcedestination node pair that satisfies two or more endtoend QoS constraints. We model this problem using a graph with n vertices and m edges with K additive QoS parameters associated with each edge, for an ..."
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Cited by 20 (6 self)
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A fundamental problem in QualityofService (QoS) routing is to find a path between a sourcedestination node pair that satisfies two or more endtoend QoS constraints. We model this problem using a graph with n vertices and m edges with K additive QoS parameters associated with each edge, for any constant K ≥ 2. This problem is known to be NPhard. Fully polynomial time approximation schemes (FPTAS) for the case of K = 2 have been reported in the literature. We concentrate on the general case and make the following contributions. (1) We present a very simple O(Km + n log n) time Kapproximation algorithm that can be used in hopbyhop routing protocols. (2) We present an FPTAS for one optimization version of the QoS routing problem with a time complexity of O(m ( n ɛ)K−1). (3) We present an FPTAS for another optimization version of the QoS routing problem with a time complexity of O(n log n + m ( H ɛ)K−1) when there exists an Hhop path satisfying all QoS constraints. When K is reduced to 2, our results compare favorably with existing algorithms. The results of this paper hold for both directed and undirected graphs. For ease of presentation, undirected graph is used.
Statistical QoS routing for IEEE 802.11 multihop ad hoc networks
 IEEE Trans. Wireless Commun
, 2009
"... Abstract—In this paper, we propose a modelbased qualityofservice (QoS) routing scheme for IEEE 802.11 ad hoc networks. Unlike most of QoS routing schemes in the literature, the proposed scheme provides stochastic endtoend delay guarantees, instead of average delay guarantees, to delaysensitiv ..."
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Cited by 10 (2 self)
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Abstract—In this paper, we propose a modelbased qualityofservice (QoS) routing scheme for IEEE 802.11 ad hoc networks. Unlike most of QoS routing schemes in the literature, the proposed scheme provides stochastic endtoend delay guarantees, instead of average delay guarantees, to delaysensitive bursty traffic sources. Via a crosslayer design approach, the scheme selects the routes based on a geographical ondemand ad hoc routing protocol and checks the availability of network resources by using traffic source and linklayer channel modeling, taking into consideration the IEEE 802.11 characteristics and node interactions. Our scheme extends the well developed effective bandwidth theory and its dual effective capacity concept to multihop IEEE 802.11 ad hoc networks. Extensive computer simulations demonstrate that the proposed scheme is effective in satisfying the endtoend delay bound to a probabilistic limit. Index Terms—Ad hoc network, call admission control, endtoend delay, IEEE 802.11 MAC, resource allocation, routing. I.
Active Pipes: Service Composition for Programmable Networks
 In Proc. IEEE MILCOM 2001
, 2001
"... Active networks allow customized processing of data traffic within the network which can be used by applications to improve the quality of their sessions. To simplify the development of active applications in a heterogeneous environment, we propose “active pipes ” as a programming abstraction to spe ..."
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Cited by 10 (1 self)
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Active networks allow customized processing of data traffic within the network which can be used by applications to improve the quality of their sessions. To simplify the development of active applications in a heterogeneous environment, we propose “active pipes ” as a programming abstraction to specify transmission and processing requirements. We describe how an active pipe can be mapped onto network resources by a shortest path algorithm, and how optimal processing sites and a route through the network can be determined. Additionally, we propose a scalable network software architecture implementing the functionality required for active pipes. 1 I.
QoS Routing Algorithms under Inaccurate Routing Information for Bandwidth Constrained Applications
 In proceedings of the IEEE International Communications Conference (ICC'03
, 2003
"... are proposed by the IETF to improve the network performance. Moreover, some QoS routing algorithms must be added in order to optimize the path selection process. However, in highly dynamic large networks, existing QoS routing algorithms suffer from a blocking probability, which in part is due to the ..."
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Cited by 10 (5 self)
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are proposed by the IETF to improve the network performance. Moreover, some QoS routing algorithms must be added in order to optimize the path selection process. However, in highly dynamic large networks, existing QoS routing algorithms suffer from a blocking probability, which in part is due to the existence of inaccuracy in the network state information used to select the path. This paper deals with the BYPASS based routing mechanism, which was introduced in a previous paper to overcome this routing inaccuracy effect in IP/MPLS scenarios. We suggest an enhancement of the BBR mechanism to optimize the bandwidth allocation by balancing the path length and the residual bandwidth, and its performance is evaluated by simulation. KeywordsQoS Routing, MPLS, routing inaccuracy
A QoS Routing Mechanism for Reducing the Routing Inaccuracy Effects
 Proceedings of the 2nd International Workshop on QoS in Multiservice IP Networks (QoSIP 2003
, 2003
"... Abstract: Optical transport networks, based on wavelengthdivision multiplexing (WDM) with automatic switching capabilities (ASON, Automatic Switching Optical Networks) appear as a potential solution to cope with the increasingly growth of Internet traffic demands. In spite of the fact that adaptive ..."
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Cited by 9 (5 self)
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Abstract: Optical transport networks, based on wavelengthdivision multiplexing (WDM) with automatic switching capabilities (ASON, Automatic Switching Optical Networks) appear as a potential solution to cope with the increasingly growth of Internet traffic demands. In spite of the fact that adaptive routing mechanisms based on global information performs better than the ones based on local information, they are only suitable for those networks where frequent network state changes are not expected. Therefore, assuming distributed lightpath control in this optical scenario, maintaining precise global network state information on each node is almost impossible. Many factors, such as nonnegligible propagation delay, frequent state updates and hierarchical topology aggregation, can affect the precision of the global network state information. Thus, when the lightpath selection process is performed based on outdated routing information a connection blocking increment is produced. In this paper a new routing mechanism named BYPASS Based Optical Routing (BBOR) for reducin g the effects of selecting lightpaths under inaccurate network state information are suggested and evaluated by simulation. The BBOR mechanism is based on adding optical capabilities to the BYPASS Based Routing (BBR) mechanism already introduced by the authors in an IP/MPLS scenario.