In this paper, we present, QoSMIC, a multicast protocol for the Internet that supports QoS-sensitive routing, and minimizes the importance of a priori configuration decisions (such ascore selection). The protocol is resource-efficient, robust, exible, and scalable. In addition, our protocol is provably loop-free. Our protocol starts with a resources-saving tree (Shared Tree) and individual receivers switch to a QoS-competitive tree (Source-Based Tree) when necessary. In both trees, the new destination is able to choose the most promising among several paths. An innovation is that we use dynamic routing information without relying on a link state exchange protocol to provide it. Our protocol limits the effect of preconfiguration decisions drastically, by separating the management from the data transfer functions; administrative routers are not necessarily part of the tree. This separation increases the robustness, and flexibility of the protocol. Furthermore, QoSMIC is able to adapt dynamically to the conditions of the network. The QoSMIC protocol introduces several new ideas that make it more exible than other protocols proposed to date. In fact, many of the other protocols, (such asYAM, PIM-SM, BGMP, CBT) can be seen as special cases of QoSMIC. This paper presents the motivation behind, and the design of QoSMIC, and provides both analytical and experimental results to support our claims.

The future Internet is expected to support multicast applications with quality of service (QoS) requirements. To facilitate this, QoS multicast routing protocols are pivotal in enabling new receivers to join a multicast group. However, current routing protocols are either too restrictive in their search for a feasible path between a new receiver and the multicast tree, or burden the network with excessive overhead. We propose QMRP, a new QoS-aware Multicast Routing Protocol. QMRP achieves scalability by significantly reducing the communication overhead of constructing a multicast tree, yet it retains a high chance of success. This is achieved by switching between single-path routing and multiple-path routing according to the current network conditions. The high level design of QMRP makes it operable on top of any unicast routing algorithm in both intra-domain and interdomain. Its responsiveness is improved by using a termination mechanism which detects the failure as well as the succes...

This paper presents algorithms, heuristics and lower bounds for an optimal sharing of network resources among several multicast groups that coexist in the network. Group (i.e., many-to-many) multicasting is a demanding service since any member can become a sender independently from the others. We consider a shared tree as the backbone of a group multicasting session. Considering each multicast session in isolation and independently may cause congestion on some links and reduce network utilization. Thus, we define the multicast packing problem in which network tries to accommodate simultaneously all the multicast groups while trying to avoid bottlenecks on the links for higher throughput (i.e., minimize the maximum link sharing among multicast groups). Minimization of maximum congestion is achieved at the expense of increasing the size of some multicast tree which in turn impacts the delay. This trade off is addressed by adding a penalty term to the objective function of the optimal pac...

AbstractÐAn anycast packet is one that should be delivered to one member in a group of designated recipients. Using anycast services may considerably simplify some applications. Little work has been done on routing anycast packets. In this paper, we propose and analyze a routing protocol for anycast message. It is composed of two subprotocols: the routing table establishment subprotocol and the packet forwarding subprotocol. In the routing table establishment subprotocol, we propose four methods (SSP, MIN-D, SBT, and CBT) for enforcing an order among routers for the purpose of loop prevention. These methods differ from each other on information used to maintain orders, the impact on QoS, and the compatibility to the existing routing protocols. In the packet forwarding subprotocol, we propose a Weighted-Random Selection (WRS) approach for multiple path selection in order to balance network traffic. In particular, the fixed and adaptive methods are proposed to determine the weights. Both of them explicitly take into account the characteristics of distribution of anycast recipient group while the adaptive method uses the dynamic information of the anycast traffic as well. Correctness property of the protocol is formally proven. Extensive simulation is performed to evaluate our newly designed protocol. Performance data shows that the loop-prevention methods and the WRS approaches have great impact on the performance in terms of average end-to-end packet delay. In particular, the protocol using the SBT or CBT loop-prevention methods and the adaptive WRS approach performs very close to a dynamic optimal routing protocol in most cases. Index TermsÐAnycast message, multiple path routing, shortest path first, weight assignment. 1

In this paper, we present a novel distributed algorithm that dynamically selects game servers for a group of game clients participating in large scale interactive online games. The goal of server selection is to minimize server resource usage while satisfying the real-time delay constraint. We develop a synchronization delay model for interactive games and formulate the server selection problem, and prove that the considered problem is NP-hard. The proposed algorithm, called zoom-in-zoom-out, is adaptive to session dynamics (e.g. clients join and leave) and lets the clients select appropriate servers in a distributed manner such that the number of servers used by the game session is minimized. Using simulation, we present the performance of the proposed algorithm and show that it is simple yet effective in achieving its design goal. In particular, we show that the performance of our algorithm is comparable to that of a greedy selection algorithm, which requires global information and excessive computation.

ABSTRACT: Hierarchies provide scalability in large net-works and are integral to many widely-used protocols and applications. Previous approaches to constructing hierar-chies have typically either assumed static hierarchy configu-ration, or have used bottom-up construction methods. We describe how to construct hierarchies in a top-down fash-ion, and show that our method is much more efficient than bottom-up methods. We also show that top-down hierarchy construction is a better choice when administrative policy constraints are imposed on hierarchy formation. 1

This paper presents algorithms, heuristics and lower bounds addressing optimization issues in many-to-many multicasting. Two main problems are addressed: (1) a precise combinatorial comparison of optimal multicast trees with optimal multicast rings, (2) an optimized sharing of network resources (i.e., nodes and links) among multiple multicast groups that coexist. The former is central to the choice of multicast protocols and their performance, while the latter is crucial for network utilization. The first problem is treated as a comparison of Steiner Tree and Traveling Salesman problems on the same input set. The underlying integer programming problems are solved to optimum by using cutting-plane inequalities and the branchand-cut algorithm. In addition to these exact solutions, fast heuristics are presented for approximate solutions. The second problem is formulated as a packing problem in which the network tries to accommodate all the multicast groups by optimizing the utilization of resources. Precise mathematical programming formulations, lower bounds and a heuristic for the underlying optimization problem are presented. The heuristic aims to accommodate multiple multicast groups while avoiding bottlenecks on the links for higher throughput. The heuristics and exact algorithms are implemented on various networks and multicast groups. The simulations show that multicast trees can be built by using 25 % fewer links than the rings, both for optimal and suboptimal constructions. The packing heuristic is also implemented and its performance is compared to the constructive lower bound.

We present a multicast routing protocol called Distributed Core Multicast (DCM). It is intended for use within a large single Internet domain network with a very large number of multicast groups with a small number of receivers. Such a case occurs, for example, when multicast addresses are allocated to mobile hosts, as a mechanism to manage Internet host mobility or in large distributed simulations. For such cases, existing dense or sparse mode multicast routing algorithms do not scale well with the number of multicast groups. DCM is based on an extension of the centre-based tree approach. It uses several core routers, called Distributed Core Routers (DCRs) and a special control protocol among them. DCM aims: (1) avoiding multicast group state information in backbone routers, (2) avoiding triangular routing across expensive backbone links, (3) scaling well with the number of multicast groups. We evaluate the performance of DCM and compare it to an existing sparse mode routing protocol when there is a large number of small multicast groups. We also analyse the behaviour of DCM when the number of receivers per group is not a small number.

In the age of multimedia and high-sl)eed networks', multicast is one of the mechanisms by which the power of the Internet can be further harnessed in an efficient manner. When more than one receiver is interested in receiving a transmission from a single or a set of senders, multicast is the most efficient and viable mechanism. In the protocol stack of the network, multicast is best implemented in the network layer in the form of a multicast routing protocol to select the best path for the transmission. The other layers' of the protocol stack provide additional features for multicast.

The Core-based approach is inevitable in multicast routing protocols as it provides efficient management of multicast path in changing group memberships, and scalability and performance. In this paper, we present a comprehensive analysis of this approach with the emphasis on core selection for the first time in literature. We first examine the evolution of multicast routing protocols into the core-based architecture and the motivation for the approach. Then we review the core-selection algorithms in the literature for their algorithmic structure and performance. Our study involves an extensive computational and message complexity analysis of each algorithm, and a classification for their deployment characteristics and algorithmic complexities. To the best of our knowledge ours is the first paper providing such extensive comparative analysis of core-based multicast routing protocols. 1.