A scalable multicast routing protocol for building shortest path trees

Scalability is a great concern in the design of multicast routing protocols for the global Internet. Building shortest path trees (SPT) is currently one of the most widely used approaches to supporting multicast routing because of the simplicity and low per‐destination cost of such trees. However, the construction of an SPT typically involves high protocol overhead, which leads to the scalability problem as the number of concurrent multicast sessions increases. In this paper, we present a destination‐initiated shortest path tree (DSPT) routing protocol. The design objective is to effectively reduce the protocol overhead associated with SPT constructions for providing scalable multicast. To achieve this objective, we introduce destination‐initiated joining operations in constructing SPTs. With DSPT, each router receiving a request to join a specific multicast group makes a local decision on selecting its parent node through which it connects to the existing tree. A source‐rooted SPT is built as a result of such collaborative operations at nodes. DSPT requires only limited routing information at routers. Analytical results demonstrate that DSPT scales well with respect to computation, storage and communication overhead when the number of concurrent multicast requests is large. Simulation experiments are also conducted to verify the correctness of the theoretically deduced analytical results. Copyright © 2006 John Wiley & Sons, Ltd.     

Enabling scalable multicast protocols using dynamic overlap tree path

The scalability of a multicast protocol is a very critical issue when it is implemented on a global scale. The number of forwarding states that are maintained at each multicast router explodes when the number of multicast groups grows exponentially as in the case of global Internet. In this paper we describe a technique, called dynamic overlap tree path (DOTP), to reduce the forwarding states that need to be maintained in multicast routers and hence improve the scalability of existing multicast protocols. This technique, which can be incorporated in both the dense and sparse modes of multicast protocols, dynamically finds overlapped unbranched tree paths and merges their corresponding forwarding states to reduce the storage requirement in multicast routers. It does not introduce any additional control‐message overheads through the reduction process. OPNET simulation results show that the overall average forwarding‐state table size of the simulated networks can be reduced by about 30 per cent on the average. Copyright © 2001 John Wiley & Sons, Ltd.     

Optimal deterministic timeouts for reliable scalable multicast

Reliable multicast protocols suffer from the problem of feedback implosion. To avoid this problem, the number of receivers sending feedback in case of loss must be small. However, losses experienced by different receivers are strongly correlated, since receivers share common resources in the multicast tree. One approach to feedback implosion avoidance relies on delaying feedback at the receivers. We present deterministic timeouts for reliable multicast (DTRM), a distributed algorithm to compute optimal deterministic timeouts for each receiver in a multicast tree as a function of the tree topology and the sender-to-receiver round-trip delays. DTRM has several desirable properties. First, feedback implosion is provably avoided for a single loss anywhere in the tree, provided delay jitter is bounded. Second, the computation of the timeouts can be entirely distributed; receivers and intermediate nodes only rely on local topology information. Third, the timeouts computed by DTRM are optimal with respect to the maximum response time     

A protocol for scalable loop-free multicast routing

In network multimedia applications such as multiparty teleconferencing, users often need to send the same information to several (but not necessarily all) other users. To manage such one-to-many or many-to-many communication efficiently in wide-area internetworks, it is imperative to support and perform multicast routing. Multicast routing sends a single copy of a message from a source to multiple receivers over a communication link that is shared by the paths to the receivers. Loop-freedom is an especially important consideration in multicasting because applications using multicasting tend to be multimedia and bandwidth intensive, and loops in multicast routing duplicate looping packets. We present and verify a new multicast routing protocol, called multicast Internet protocol (MIP), which offers a simple and flexible approach to constructing both group-shared and shortest-paths multicast trees. MIP can be sender-initiated or receiver-initiated or both; therefore, it can be tailored to the particular nature of an application's group dynamics and size. MIP is independent of the underlying unicast routing algorithms used. MIP is robust and adapts under dynamic network conditions (topology or link cost changes) to maintain loop-free multicast routing. Under stable network conditions, MIP has no maintenance or control message overhead. We prove that MIP is loop-free at every instant, and that it is deadlock-free and obtains multicast routing trees within a finite time after the occurrence of an arbitrary sequence of topology or unicast changes     

Resilient peer-to-peer streaming of scalable video over hierarchical multicast trees with backup parent pools

This paper introduces a new cross layer tree-based peer-to-peer design using hierarchical cluster layers and a new method for selection of “backup parent pools” for resilient streaming of scalable video to provide highest quality of experience for all peers. Backup parent pools are selected during the process of multicast tree construction based on information provided by the hierarchical clusters. The proposed tree construction method aims to minimize bottlenecks that may be caused by non-leaf nodes with low upload bandwidth. Performance of the proposed system is demonstrated by extensive test results using a wide range of simulation scenarios. Comparison of the results with those of some recent works indicates that the proposed system is clearly superior in several aspects.     

一种改进的Steiner树启发式算法

最小Steiner树问题是NP完全问题，关于Steiner问题的启发式算法的研究具有重要理论和实际意义。本文在MPH算法基础上，对于经过某些关键节点的短路径优先考虑，提出了KBMPH算法，从而实现更多链路的共享。在随机网络上的仿真结果表明，极大多数情况下，在准Steiner树的网络费用KBMPH算法优于MPH算法，KBMPH算法的复杂度为O（n^3）。     

Steiner trees in probabilistic networks

Various network reliability problems are #P-complete, however, certain classes of networks such as series-parallel networks, admit polynomial time algorithms. We extend these efficient methods to a superclass of series-parallel networks, the partial 2-trees. In fact, we solve a more general problem: given a probabilistic partial 2-tree and a set T of target nodes, we compute in linear time the probability of obtaining a subgraph connecting all of the target nodes. Equivalently, this is the probability of obtaining a Steiner tree for T. The algorithm exploits a characterization of partial 2-trees as graphs with no subgraph homeomorphic to K₄.     

Power aware scalable multicast routing protocol for MANETs

Multicasting is an effective way to provide group communication. In mobile ad hoc networks (MANETs), multicasting can support a wide variety of applications that are characterized by a close degree of collaboration. Since MANETs exhibit severe resource constraints such as battery power, limited bandwidth, dynamic network topology and lack of centralized administration, multicasting in MANETs become complex. The existing multicast routing protocols concentrate more on quality of service parameters like end‐to‐end delay, jitter, bandwidth and power. They do not stress on the scalability factor of the multicast. In this paper, we address the problem of multicast scalability and propose an efficient scalable multicast routing protocol called ‘Power Aware Scalable Multicast Routing Protocol (PASMRP)’ for MANETs. PASMRP uses the concept of class of service with three priority levels and local re‐routing to provide scalability. The protocol also ensures fair utilization of the resources among the nodes through re‐routing and hence the lifetime of the network is increased. The protocol has been simulated and the results show that PASMRP has better scalability and enhanced lifetime than the existing multicast routing protocols. Copyright © 2005 John Wiley & Sons, Ltd.     

Cryptanalysis of scalable multicast security protocol

We show that the scalable multicast security protocol based on RSA, proposed by R. Molva and A. Pannetrat (see ACM Trans. Inform. Syst. Security, vol.3, no.3, p.136-60, 2000), is insecure against collusion attacks.     

A large scalable ATM multicast switch

This paper focuses on designing a large N×N high-performance broad-band ATM switch. Despite advances in architectural designs, practical switch dimensions continue to be severely limited by both the technological and physical constraints of packaging. Here, we focus on augmentation in a “single-switch” design: we provide ways to construct arbitrarily large switches out of modest-size components and retain overall delay/throughput performance. We propose a growable switch architecture based on several key principles: 1) the knockout principle exploits the statistical behavior of cell arrivals, and thereby reduces the interconnect complexity; 2) output queueing yields the best possible delay/throughput performance; 3) distributed control in routing (multicast) cells through the interconnect fabric without internal path conflicts; and 4) simple basic building blocks facilitate scalability. Other attractive features of the proposed architecture include: 1) intrinsic broadcast and multicast capabilities; 2) built-in priority sorting functionality; and 3) the guarantee of first-in, first-out cell sequence, To achieve 10^-14 cell loss probability, only maximum size 32×16 basic building modules are required, and no crossover interconnects exist between modules in a three-dimensional configuration     

Fast vicinity-upgrade algorithm for rectilinear Steiner trees

A new algorithm for rectilinear Steiner trees (RST) is presented. The proposed algorithm is based on successively constructing a vicinity structure from a rectilinear minimum spanning tree (MST) and generating a refined RST. The algorithm achieves an 8.5-10% average cost improvement over the rectilinear MST at a time complexity of O(n log n). To address specifically the linear programming approach of global routing the algorithm is modified to generate K trees.<>     

Bottleneck multicast trees in linear time

On a directed graph with arc costs and a given source node, s, we consider the problem of computing multicast (Steiner) trees spanning any given node subset, V, so that the maximum of the tree arc costs is minimized. We show that this problem can be solved by simply solving the bottleneck path problem, i.e., the problem of determining for each node, t/spl ne/s, a path from s to t so that the maximum of path arc costs is minimized. For the latter problem we provide an implementation of Dijkstra's algorithm that runs in linear time under mild assumptions on arc costs.     

A scalable multicast key management scheme for heterogeneous wireless networks

Secure multicast applications require key management that provides access control. In wireless networks, where the error rate is high and the bandwidth is limited, the design of key management schemes should place emphasis on reducing the communication burden associated with key updating. A communication-efficient class of key management schemes is those that employ a tree hierarchy. However, these tree-based key management schemes do not exploit issues related to the delivery of keying information that provide opportunities to further reduce the communication burden of rekeying. In this paper, we propose a method for designing multicast key management trees that match the network topology. The proposed key management scheme localizes the transmission of keying information and significantly reduces the communication burden of rekeying. Further, in mobile wireless applications, the issue of user handoff between base stations may cause user relocation on the key management tree. We address the problem of user handoff by proposing an efficient handoff scheme for our topology-matching key management trees. The proposed scheme also addresses the heterogeneity of the network. For multicast applications containing several thousands of users, simulations indicate a 55%-80% reduction in the communication cost compared to key trees that are independent of the network topology. Analysis and simulations also show that the communication cost of the proposed topology-matching key management tree scales better than topology-independent trees as the size of multicast group grows.     

SVC分层视频流在有线网络中的多码率组播优化

主要研究了可分级视频编码（SVC）在有线网络中进行多码率组播时,对于视频传输质量以及路由选择进行联合优化的问题。为了获得有线网络中视频流分层接收的最优化,提出了基于网络编码约束的凸优化模型,并且在SVC编码约束下保证了每个接收节点以递增的顺序获得分层的视频流,最终能够联合地优化组播的路由以及相应的码率。而使用分解理论中的原始分解和对偶分解方法,将原来较为复杂的优化问题分解为两层优化子问题,并且提出了求解整个联合优化问题的分布式解法。     

A scalable low-overhead rate control algorithm for multirate multicast sessions

In multirate multicasting, different users (receivers) within the same multicast group can receive service at different rates, depending on the user requirements and the network congestion level. Compared with unirate multicasting, this provides more flexibility to the user and allows more efficient usage of the network resources. We address the rate control problem for multirate multicast sessions, with the objective of maximizing the total receiver utility. This aggregate utility maximization problem not only takes into account the heterogeneity in user requirements, but also provides a unified framework for diverse fairness objectives. We propose an algorithm for this problem and show, through analysis and simulation, that it converges to the optimal rates. In spite of the nonseparability of the problem, the solution that we develop is completely decentralized, scalable and does not require the network to know the receiver utilities. The algorithm requires very simple computations both for the user and the network, and also has a very low overhead of network congestion feedback.     

Cognitive radio assisted quality compensation for scalable video multicast in cellular networks

Existing multicast schemes always employ the scalable video coding (SVC) to accommodate heterogeneous channel conditions. Although this method achieves a high spectral efficiency, it will lead to serious quality imbalance problem, i.e., the viewers who hold a better link conditions can obtain high video quality, but the viewers with bad reception conditions can only receive the video with poor quality. In this paper, we propose a novel Cognitive Radio Assisted Quality Compensation (CRAQC) scheme for enhancing the video quality of bad reception viewers. In CRAQC, the bad reception viewers can obtain from the good reception viewers the video content they cannot receive directly from the base station using cognitive relay links. One novel and promising design of the proposed scheme is that it considers a cooperative transmission style in relay process, in which viewers with the same relay content can simultaneously broadcast this content in the same channel, and therefore achieve the benefits of space diversity to the receiver. Through extensive simulations, we demonstrate that CRAQC is able to significantly improve the video performance of the bad reception viewers.     

An ATM routing and concentration chip for a scalable multicast ATMswitch

We have proposed a new architecture for building a scalable multicast ATM switch from a few tens to a few thousands of input/output ports. The switch, called the Abacus switch, employs input and output buffering schemes. Cell replication, cell routing, and output contention resolution are all performed in a distributed way so that the switch can be scaled up to a large size. The Abacus switch adopts a novel algorithm to resolve the contention of both multicast and unicast cells destined for the same output port (or output module). The switch can also handle multiple priority traffic by routing cells according to their priority levels. This paper describes a key ASIC chip for building the Abacus switch. The chip, called the ATM routing and concentration (ARC) chip, contains a two-dimensional array (3×32) of switch elements that are arranged in a cross-bar structure. It provides the flexibility of configuring the chip into different group sizes to accommodate different ATM switch sizes. The ARC chip has been designed and fabricated using 0.8-μm CMOS technology and tested to operate correctly at 240 MHz, Although the ARC chip was designed to handle the line rate at OC-3 (155 Mb/s), the Abacus switch can accommodate a much higher line rate at OC-12 (622 Mb/s) or OC-48 (2.5 Gb/s) by using a bit-sliced technique or distributing cells in a cyclic order to different inputs of the ARC chip. When the latter scheme is used, the cell sequence is retained at the output of the Abacus switch     

Bandwidth-satisfied multicast trees in large-scale ad-hoc networks

The purpose of this paper is to construct bandwidth-satisfied multicast trees for QoS applications in large-scale ad-hoc networks (MANETs). Recent routing protocols and multicast protocols in large-scale MANETs adopt two-tier infrastructures to avoid the inefficiency of the flooding. Hosts with a maximal number of neighbors are often chosen as backbone hosts (BHs) to forward packets. Most likely, these BHs will be traffic concentrations/bottlenecks of the network. In addition, since host mobility is not taken into consideration in BH selection, these two-tier schemes will suffer from more lost packets if highly mobile hosts are selected as BHs. In this paper, a new multicast protocol is proposed for partitioning large-scale MANET into two-tier infrastructures. In the proposed two-tier multicast protocol, hosts with fewer hops and longer remaining connection time to the other hosts will be selected as BHs. The objective is not only to obtain short and stable multicast routes, but also to construct a stable two-tier infrastructure with fewer lost packets. Further, previous MANET quality-of-service (QoS) routing/multicasting protocols determined bandwidth-satisfied routes for QoS applications. Some are implemented as a probing scheme, but the scheme is inefficient due to high overhead and slow response. On the contrary, the others are implemented by taking advantage of routing and link information to reduce the inefficiency. However, the latter scheme suffers from two bandwidth-violation problems. In this paper, a novel algorithm is proposed to avoid the two problems, and it is integrated with the proposed two-tier multicast protocol to construct bandwidth-satisfied multicast trees for QoS applications in large-scale MANETs. The proposed algorithm aims to achieve better network performance by minimizing the number of forwarders in a tree.     

Efficient scalable video multicast based on network-coded communication

In order to increase the efficiency of mobile video transmission in a 5G network, this paper investigates a cooperative multicast of scalable video using network coding with adaptive modulation and coding over dedicated relay-based cellular networks. Different scalable video layers prefer different protection degrees, and user equipments (UEs) in different locations experience different packet loss rates in wireless networks. Guaranteeing that all UEs experience a certain level of video quality is one of the biggest challenges in scalable video multicast. Using the number of satisfied UEs as a metric, the proposed efficient scalable video multicast based on network-coded cooperation (SVM-NC) scheme, combined with adaptive modulation and coding, enhances the attainable system performance under strict time and bandwidth resource constraints for guaranteed smooth playback. Various simulations were performed for performance evaluation. The proposed scheme ensures that the expected percentage of satisfied UEs approximately achieves the maximum number of UEs in a multicast group by using network-coded cooperation over dedicated relay-based cellular networks. In addition, the peak signal-to-noise ratio metric is asymptotic to the maximum performance of high-resolution video quality offered by service providers.     

On properties of multicast routing trees

In the last several years we witnessed the proliferation of multimedia applications on the Internet. One of the unavoidable techniques to support this type of communication is multicasting. However, even a decade after its initial proposal, multicast is still not widely deployed. One of the reasons is the lack of a solid business model. If the gain and the cost of multicast could be predicted, network operators might be encouraged to deploy multicast on a larger scale. In this paper we propose analytical expressions that could be used to estimate the gain of network‐layer multicast. We show that the theoretical model matches extensive simulation and Internet measurement results remarkably well. Furthermore, we examine the reliability of traceroute data and of traceroutes‐based conclusions. We investigate the node degree distributions in the Internet maps obtained from CAIDA and RIPE and we show the divergency of our results with those obtained by other researchers. We further focus on the analysis of multicast trees based on traceroute data. Only few results have been available on the node degree distribution of multicast routing trees which provided contradictory conclusions. Our results seem to indicate that the node degrees follow power laws only for a large number of multicast users. Copyright © 2005 John Wiley & Sons, Ltd.