The Experts below are selected from a list of 130773 Experts worldwide ranked by ideXlab platform

Hussein T. Mouftah - One of the best experts on this subject based on the ideXlab platform.

  • forwarding state reduction for delay constrained multicasting in ip networks
    Global Communications Conference, 2003
    Co-Authors: Baoxian Zhang, Hussein T. Mouftah
    Abstract:

    The multicast forwarding state scalability issue is one of the critical issues that delay the deployment of IP multicast in the global Internet. With traditional protocols, each router is required to maintain a forwarding entry locally for each group whose Distribution Tree passes through the router itself. Consequently, the number of forwarding entries at routers increases linearly with the number of concurrent ongoing multicast sessions. This can pose the forwarding state scalability issue when the number of multicast sessions is very large. The paper addresses this scalability issue in providing efficient delay-constrained multicasting in IP networks. We propose a scalable multicast routing heuristic. Its computational complexity is deduced to be O(m|V|/sup 2/), where m is the size of the multicast group and |V| is the size of the network. In particular, if the heuristic is executed online, its computational complexity can be further reduced to O(m/sup 2/). This property makes the heuristic scale well with the number of concurrent sessions since multicasting subject to a delay constraint is typically executed on a per-session basis. Simulation results show that the proposed heuristic can achieve high performance in reducing the forwarding state at routers and in utilizing network resources efficiently.

  • Forwarding state scalability for multicast provisioning in IP networks
    IEEE Communications Magazine, 2003
    Co-Authors: Baoxian Zhang, Hussein T. Mouftah
    Abstract:

    Forwarding state scalability is one of the critical issues that delay the multicast deployment in IP networks. With traditional multicast routing protocols, a forwarding Tree is built for each multicast session, and each router is required to maintain a forwarding entry for each multicast session whose Distribution Tree passes through the router. This poses the multicast forwarding state scalability issue when the number of concurrent multicast sessions is very large. We first present a survey of existing work addressing this scalability issue for providing scalable IP multicast. Then we extend an existing multicast routing protocol, Multicast Extension to OSPF (MOSPF), to scale well with respect to the number of concurrent multicast sessions by introducing tunnel support. This extension aims to reduce the protocol overhead associated with MOSPF. Simulation results show that the extension can significantly reduce multicast forwarding state and computational overhead at routers without affecting the per-destination shortest path characteristic of a resulting Tree or introducing extra control overhead.

Manh-cuong Nguyen - One of the best experts on this subject based on the ideXlab platform.

  • Application-network cross layer multi-variable cost function for application layer multicast of multimedia delivery over convergent networks
    Wireless Networks, 2015
    Co-Authors: Tien Anh Le, Hang Nguyen, Manh-cuong Nguyen
    Abstract:

    Application layer multicast (ALM) algorithms are either similar or conceptually based on network layer multicast’s cost functions. In this research work, a new application-network cross layer multi-variable cost function is proposed. It optimizes the variable requirements and available resources from both the application and the network layers. It can dynamically update the available resources required for reaching a particular node on the ALM’s media Distribution Tree. Mathematical derivation and theoretical analysis have been provided for the newly proposed cost function so that it can be applied in more general cases of different contexts. An evaluation platform of an overlay network built over a convergent underlay network comprised of a simulated Internet topology and a real 4G mobile WiMAX IEEE802.16e wireless network is constructed. The performance of the newly proposed cross-layer multi-variable cost function is evaluated and compared with conventional cost functions in scalable video coding-based services such as video multicast and video conferencing services using the evaluation platform. Intensive evaluation results have shown that the newly proposed cross-layer multi-variable cost function outperforms the conventional cost function and improves the performance of multimedia services on dynamic convergent network environments.

Deborah Estrin - One of the best experts on this subject based on the ideXlab platform.

  • the stress method for boundary point performance analysis of end to end multicast timer suppression mechanisms
    IEEE ACM Transactions on Networking, 2004
    Co-Authors: Ahmed Helmy, S K Gupta, Deborah Estrin
    Abstract:

    The advent of multicast and the growth and complexity of the Internet has complicated network protocol design and evaluation. Evaluation of Internet protocols usually uses random scenarios or scenarios based on designers' intuition. Such an approach may be useful for average case analysis but does not cover boundary-point (worst or best case) scenarios. To synthesize boundary-point scenarios, a more systematic approach is needed. In this paper, we present a method for automatic synthesis of worst and best case scenarios for protocol boundary-point evaluation. Our method uses a fault-oriented test generation (FOTG) algorithm for searching the protocol and system state space to synthesize these scenarios. The algorithm is based on a global finite state machine (FSM) model. We extend the algorithm with timing semantics to handle end-to-end delays and address performance criteria. We introduce the notion of a virtual LAN to represent delays of the underlying multicast Distribution Tree. Our algorithms utilize implicit backward search using branch and bound techniques and start from given target events. As a case study, we use our method to evaluate variants of the timer suppression mechanism, used in various multicast protocols, with respect to two performance criteria: overhead of response messages and response time. Simulation results for reliable multicast protocols show that our method provides a scalable way for synthesizing worst case scenarios automatically. Results obtained using stress scenarios differ dramatically from those obtained through average case analyses. We hope for our method to serve as a model for applying systematic evaluation to other multicast protocols.

  • the stress method for boundary point performance analysis of end to end multicast timer suppression mechanisms
    arXiv: Networking and Internet Architecture, 2002
    Co-Authors: Ahmed Helmy, S K Gupta, Deborah Estrin
    Abstract:

    Evaluation of Internet protocols usually uses random scenarios or scenarios based on designers' intuition. Such approach may be useful for average-case analysis but does not cover boundary-point (worst or best-case) scenarios. To synthesize boundary-point scenarios a more systematic approach is needed.In this paper, we present a method for automatic synthesis of worst and best case scenarios for protocol boundary-point evaluation. Our method uses a fault-oriented test generation (FOTG) algorithm for searching the protocol and system state space to synthesize these scenarios. The algorithm is based on a global finite state machine (FSM) model. We extend the algorithm with timing semantics to handle end-to-end delays and address performance criteria. We introduce the notion of a virtual LAN to represent delays of the underlying multicast Distribution Tree. The algorithms used in our method utilize implicit backward search using branch and bound techniques and start from given target events. This aims to reduce the search complexity drastically. As a case study, we use our method to evaluate variants of the timer suppression mechanism, used in various multicast protocols, with respect to two performance criteria: overhead of response messages and response time. Simulation results for reliable multicast protocols show that our method provides a scalable way for synthesizing worst-case scenarios automatically. Results obtained using stress scenarios differ dramatically from those obtained through average-case analyses. We hope for our method to serve as a model for applying systematic scenario generation to other multicast protocols.

  • systematic testing of multicast routing protocols analysis of forward and backward search techniques
    arXiv: Networking and Internet Architecture, 2000
    Co-Authors: Ahmed Helmy, Deborah Estrin, S K Gupta
    Abstract:

    In this paper, we present a new methodology for developing systematic and automatic test generation algorithms for multipoint protocols. These algorithms attempt to synthesize network topologies and sequences of events that stress the protocol's correctness or performance. This problem can be viewed as a domain-specific search problem that suffers from the state space explosion problem. One goal of this work is to circumvent the state space explosion problem utilizing knowledge of network and fault modeling, and multipoint protocols. The two approaches investigated in this study are based on forward and backward search techniques. We use an extended finite state machine (FSM) model of the protocol. The first algorithm uses forward search to perform reduced reachability analysis. Using domain-specific information for multicast routing over LANs, the algorithm complexity is reduced from exponential to polynomial in the number of routers. This approach, however, does not fully automate topology synthesis. The second algorithm, the fault-oriented test generation, uses backward search for topology synthesis and uses backtracking to generate event sequences instead of searching forward from initial states. Using these algorithms, we have conducted studies for correctness of the multicast routing protocol PIM. We propose to extend these algorithms to study end-to-end multipoint protocols using a virtual LAN that represents delays of the underlying multicast Distribution Tree.

  • a dynamic bootstrap mechanism for rendezvous based multicast routing
    In: (pp. pp. 1090-1098). IEEE (1999), 1999
    Co-Authors: Deborah Estrin, Ahmed Helmy, Mark Handley, Polly Huang, David G. Thaler
    Abstract:

    Current multicast routing protocols can be classified into three types according to how the multicast Tree is established: broadcast and prune (e.g., DVMRP, PIM-DM), membership advertisement (e.g., MO-SPF), and rendezvous-based (e.g., CBT, PIM-SM). Rendezvous-based protocols associate with each logical multicast group address, a physical unicast address, referred to as the 'core' or 'rendezvous point' (RP). Members first join a multicast Tree rooted at this rendezvous point in order to receive data packets sent to the group. Rendezvous mechanisms are well suited to large wide-area networks because they distribute group-specific data and membership information only to those routers that are on the multicast Distribution Tree. However, rendezvous protocols require a bootstrap mechanism to map each logical multicast address to its current physical rendezvous point address. The bootstrap mechanism must adapt to network and router failures but should minimize unnecessary changes in the group-to-RP mapping. In addition, the bootstrap mechanism should be transparent to the hosts. This paper describes and analyzes the bootstrap mechanism developed for PIM-SM. The mechanism employs an algorithmic mapping of multicast group to rendezvous point address, based on a set of available RPs distributed throughout a multicast domain. The primary evaluation measures are convergence time, message Distribution overhead, balanced assignment of groups to RPs, and host impact. The mechanism as a whole, and the design lessons in particular, are applicable to other rendezvous-based multicast routing protocols as well.

Baoxian Zhang - One of the best experts on this subject based on the ideXlab platform.

  • forwarding state reduction for delay constrained multicasting in ip networks
    Global Communications Conference, 2003
    Co-Authors: Baoxian Zhang, Hussein T. Mouftah
    Abstract:

    The multicast forwarding state scalability issue is one of the critical issues that delay the deployment of IP multicast in the global Internet. With traditional protocols, each router is required to maintain a forwarding entry locally for each group whose Distribution Tree passes through the router itself. Consequently, the number of forwarding entries at routers increases linearly with the number of concurrent ongoing multicast sessions. This can pose the forwarding state scalability issue when the number of multicast sessions is very large. The paper addresses this scalability issue in providing efficient delay-constrained multicasting in IP networks. We propose a scalable multicast routing heuristic. Its computational complexity is deduced to be O(m|V|/sup 2/), where m is the size of the multicast group and |V| is the size of the network. In particular, if the heuristic is executed online, its computational complexity can be further reduced to O(m/sup 2/). This property makes the heuristic scale well with the number of concurrent sessions since multicasting subject to a delay constraint is typically executed on a per-session basis. Simulation results show that the proposed heuristic can achieve high performance in reducing the forwarding state at routers and in utilizing network resources efficiently.

  • Forwarding state scalability for multicast provisioning in IP networks
    IEEE Communications Magazine, 2003
    Co-Authors: Baoxian Zhang, Hussein T. Mouftah
    Abstract:

    Forwarding state scalability is one of the critical issues that delay the multicast deployment in IP networks. With traditional multicast routing protocols, a forwarding Tree is built for each multicast session, and each router is required to maintain a forwarding entry for each multicast session whose Distribution Tree passes through the router. This poses the multicast forwarding state scalability issue when the number of concurrent multicast sessions is very large. We first present a survey of existing work addressing this scalability issue for providing scalable IP multicast. Then we extend an existing multicast routing protocol, Multicast Extension to OSPF (MOSPF), to scale well with respect to the number of concurrent multicast sessions by introducing tunnel support. This extension aims to reduce the protocol overhead associated with MOSPF. Simulation results show that the extension can significantly reduce multicast forwarding state and computational overhead at routers without affecting the per-destination shortest path characteristic of a resulting Tree or introducing extra control overhead.

Kamal Jain - One of the best experts on this subject based on the ideXlab platform.

  • a comparison of network coding and Tree packing
    International Symposium on Information Theory, 2004
    Co-Authors: P A Chou, Kamal Jain
    Abstract:

    Network coding solutions and routing solutions, namely packing Distribution Trees, for the problem of information multicast is compared in this paper. To enable the comparison, we develop greedy Tree packing algorithms that repeatedly pack the maximum-rate Distribution Tree and a greedy Tree packing algorithm based on Lovasz' proof to Edmonds' theorem. We then investigate the potential advantages of network coding over routing. In terms of throughput, Tree packing performs comparably to network coding on the network graphs of six Internet service providers. However, network coding offers additional benefits, including fewer network resources consumed, ease of management, and robustness.