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ABSTRACT: For label switched networks, such as MPLS and GMPLS, most existing traffic engineering solutions work in a single routing domain. These solutions do not work when a route from the ingress node to the egress node leaves the routing area or autonomous system of the ingress node. In such cases, the path computation problem becomes complicated because of the unavailability of the complete routing information throughout the network. This is because service providers usually choose not to leak routing information beyond the routing area or AS for scalability constraints and confidentiality concerns. This article serves two purposes. First, it provides a description of the existing and ongoing work in interdomain TE within the IETF. This information is currently found in various Internet drafts and has not yet been collectively presented in a single document. To this end, a summary of both existing path computation architectures - PCE-based and per-domain - is provided. Second, it compares two per-domain path computation schemes in terms of the total number of LSPs successfully placed and average number of domains crossed, without assuming availability of complete topology information. We notice that the two per-domain path computation schemes, proposed in [1, 2], have comparable path computation complexities and setup latencies.
IEEE Communications Magazine 11/2007; · 3.79 Impact Factor
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ABSTRACT: For label switched networks, such as MPLS and GMPLS, most existing traffic engineering (TE) solutions work in a single routing domain. These solutions do not work when a route from the ingress node to the egress node leaves the routing area or the autonomous system (AS) of the ingress node. In such cases, the path computation problem becomes complicated because of the unavailability of the complete routing information throughout the network. We present CWS (computation while switching), a new inter-domain path computation scheme which tries to compute a near-optimal path without assuming the availability of complete topology information. We provide a detailed comparison of the CWS scheme with another per-domain path computation scheme given in J.-P. Vasseur et al. (2006). Unlike the standard per-domain path computation scheme (Vasseur et al., 2006), the CWS scheme continues the quest for a better path instead of terminating the search at the first available path, resulting a significant improvement in terms of path optimality. In particular, CWS guarantees that, for a given network state, a computed inter-domain path will traverse a minimum number of domains. This improvement in path computation directly impacts the amount of traffic that can be allowed on the network. For example, for the COST266 topology with 28 domains and 37 bidirectional inter-domain links, CWS places 960 of the requested 2000 paths as compared to 683 paths placed by existing schemes. Finally, the path setup latency of the CWS scheme remains comparable to that of existing schemes, by allowing the data flow as soon as the first feasible path is found.
Communications, 2007. ICC '07. IEEE International Conference on; 07/2007
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ABSTRACT: In label-switched networks such as MPLS, protection routing involves computing and setting up the backup paths at the same time when the primary paths are routed. It has previously been shown that two or more backup paths may share bandwidth along common links if such backup paths will never be activated simultaneously. Such sharing between the backup paths leads to reduced bandwidth reservations and, hence improved performance in terms of number of path requests that can be accommodated on the network (Aslam et al., 2005). We present a novel idea that backup paths may also share bandwidth with certain primary paths, thereby further reducing the overall bandwidth reservations on the network. This results in even more path requests being accommodated on the network. Sharing with primary paths is possible with any protection routing framework. To demonstrate this sharing, we use the NPP protection routing framework as an example (Aslam et al., 2005). We provide the enhancements to the NPP framework needed to exploit sharing with the primary paths. For the enhanced NPP framework, simulation results on various networks confirm that sharing with primary paths indeed results in better network utilization. This increased performance is achieved with bounded local state information and without requiring any additional routing or signaling overhead.
INFOCOM 2006. 25th IEEE International Conference on Computer Communications. Proceedings; 05/2006
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Z.A. Uzmi
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ABSTRACT: Summary form only given. MPLS Networks are known to provide flexibility of IP networks without compromising scalability. Guaranteed QoS in an MPLS network requires backup paths to be preset in the network. This tutorial introduces the single-layer restoration routing by placing primary as well as backup paths in MPLS networks. Our focus is on characterizing the fault models, computing and establishing backup paths, and bandwidth sharing along such backup paths. A quick overview of MPLS routing is provided followed by the routing information scenarios and the type of information propagated through routing protocols and their extensions. We also cover the information locally stored at MPLS nodes that assists in efficient restoration routing and the algorithms for computing backup paths using the local and propagated information.
Emerging Technologies, 2005. Proceedings of the IEEE Symposium on; 10/2005
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ABSTRACT: We present AMOR, a new scheme for on-demand routing in wireless ad hoc networks. In ad hoc networks, mobile nodes are connected to each other such that the connection pattern changes dynamically with the mobility of nodes. Therefore, classical table driven routing algorithms necessitate updated network state information to be periodically disseminated, and incur significant costs in terms of network utilization, memory, and associated update-processing. In contrast, on-demand routing algorithms do not maintain pre-computed routes and real time route discovery ensues when data traffic needs to be transmitted between a source-destination pair. AMOR employs a modified version of the Dynamic Source Routing protocol to discover multiple node-disjoint paths between a source-destination pair. A key feature of AMOR is that instead of computing minimum-hop paths, it computes paths such that a measure of the 'transmission reliability', namely ETX, between the source-destination pair is optimized. Furthermore, AMOR employs a real time loading algorithm that optimally load balances traffic across multiple paths. The control traffic overhead in AMOR is comparable to that of single-path on-demand protocols. We present analytical throughput results in a simplified AMOR model of a network of multi-radio nodes. We also conduct simulation experiments to study the throughput performance of the AMOR scheme in a network of single-radio nodes. Our results show that AMOR outperforms the traditional dynamic source routing algorithm.
Object-Oriented Real-Time Distributed Computing, 2005. ISORC 2005. Eighth IEEE International Symposium on; 06/2005
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ABSTRACT: We investigate the problem of distributed online routing of bandwidth guaranteed paths with local restoration. A unified model is proposed that captures the bandwidth sharing characteristic of backup paths that provision local restoration, corresponding to different fault models. We apply the model to describe bandwidth sharing on backup paths for varying degrees of network state information. The extent of backup bandwidth sharing depends on the amount of network state information made available through routing protocols. A key design criterion for traffic engineering schemes is to maximize the sharing between backup paths, while minimizing this protocol overhead. M.S. Kodialam and T.V. Lakshman (see Proc. Infocom, p.376-85, 2001) demonstrated that propagating a constant amount of aggregated information per link leads to cost effective bandwidth sharing. We propose oAIS, a new aggregate information scenario, in which we judiciously select the propagated information, such that the protocol overhead is identical to that of Kodialam and Lakshman. Simulations show that oAIS outperforms other information scenarios with comparable protocol overheads.
Communications, 2005. ICC 2005. 2005 IEEE International Conference on; 06/2005
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ABSTRACT: Mobility in wireless sensor networks poses unique challenges to the medium access control (MAC) protocol design. Previous MAC protocols for sensor networks assume static sensor nodes and focus on energy-efficiency. In this paper, we present a mobility-adaptive, collision-free medium access control protocol (MMAC) for mobile sensor networks. MMAC caters for both weak mobility (e.g., topology changes, node joins, and node failures) and strong mobility (e.g., concurrent node joins and failures, and physical mobility of nodes). MMAC is a scheduling-based protocol and thus it guarantees collision avoidance. MMAC allows nodes the transmission rights at particular time-slots based on the traffic information and mobility pattern of the nodes. Simulation results indicate that the performance of MMAC is equivalent to that of TRAMA in static sensor network environments. In sensor networks with mobile nodes or high network dynamics, MMAC outperforms existing MAC protocols, like TRAM A and S-MAC, in terms of energy-efficiency, delay, and packet delivery.
Performance, Computing, and Communications Conference, 2005. IPCCC 2005. 24th IEEE International; 05/2005
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ABSTRACT: In recent years many protocols for ad hoc wireless networks have been developed but very little information is available on the performance of these protocols. After describing the desirable characteristics of an ad hoc network routing protocol this paper provides an overview of four existing ad hoc wireless routing protocols, which are distance sequence distance vector (DSDV), ad hoc on demand distance vector (AODV), dynamic source routing (DSR) and temporally ordered routing algorithm (TORA). The performance comparison of these four protocols is based on simulations performed using network simulator-2. The performance parameters analyzed are the mobility rate, network load and network size. The paper describes all the parameters used for the simulations in detail and then compares each routing protocol's simulation results before arriving at a conclusion as to which is the best one for ad hoc networks.
Multitopic Conference, 2004. Proceedings of INMIC 2004. 8th International; 01/2005
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ABSTRACT: In wireless sensor networks, the small data rate, generally 16 bits per packet, makes the overhead of globally unique network and MAC addresses, which is typically as much as the payload itself, undesirable (Elson, J. and Estrin, D. ICDCS'01, 2001). We present a node address naming scheme that assigns locally unique addresses, which could be spatially reused, to nodes in an energy efficient manner; the scheme reduces the address size by a factor of 3.6. The focus of our work is solely on clustering routing approaches (Heinzelman, W., "Application-Specific Protocol Architectures for Wireless Networks", PhD thesis, MIT, 2000). Further, we question the need for separate MAC and network addresses and show how our spatially reused locally unique node address could be used in both contexts, leading to greater energy efficiency.
Networking and Communication Conference, 2004. INCC 2004. International; 07/2004
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ABSTRACT: A fundamental problem that confronts future applications of sensor networks is how to locate efficiently the sensor node that stores a particular data item. Distributed hash table (DHT) based Internet peer-to-peer (P2P) protocols provide near-optimum data lookup times for queries made on networks of distributed nodes. A generic mapping of these protocols to sensor networks is, however, perceived as difficult (Ratnasamy, S. et al., Mobile Networks and Applications, - MONET 2003). We present a novel DHT based network protocol for sensor networks - chord for sensor networks (CSN) - for which bounded times for data lookup, in the order of O(logN) messages, can be achieved in an energy efficient manner. CSN makes the system lifetime of the sensor network proportional to its effective use. Furthermore, CSN scales well to large-scale sensor networks when the information about other nodes logarithmically increases with an increase in the number of sensor nodes.
Communication Networks and Services Research, 2004. Proceedings. Second Annual Conference on; 06/2004
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ABSTRACT: Traditional network protocols such as TCP/IP require cooperation between traffic sources to achieve optimal network performance. This approach does not always work, as evident by frequent congestion problems in the Internet. Recent research in protocol design using game theory removes this limitation by modeling traffic sources as competing players and results in efficient and fair distribution of resources. This paper provides theoretical background of the game theoretic approach as applied to networks, describes some previously proposed schemes for minimizing network congestion, elaborates on pricing mechanisms and discusses game-theoretic routing solutions. Pricing provides a feasible solution for congestion control but application of distributed algorithmic mechanism design (DAMD) can be adapted for congestion control.
Parallel Architectures, Algorithms and Networks, 2004. Proceedings. 7th International Symposium on; 06/2004
