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As an alternative of IP Multicast, ALM implements multicast functionality at the application layer instead of the IP layer, which addresses the problem of non-ubiquitous deployment of IP multicast. However, the reliability of ALM is low because dynamic hosts forward the data. This paper analyzes the error and delivery features of ALM trees, and further presents a data loss recovery solution (called HBHLR) for application layer multicast.

The increased bandwidth required by applications, tends to raise the amount of optical equipment, for this reason, it is essential to maintain a balance between the wavelength allocation, available capacity and number of optical devices to achieve the lowest power consumption. You could say that we propose a model that minimizes energy consumption, using unicast / multicast traffic grooming in optical networks.

In this paper, the joint network-channel coding performance of dual hop two-way multicast relay network is compared with one-way coded multicast relay scheme. Multicast Relay transmission scheme is a type of transmission scheme in which two fixed relay nodes contribute in the second hop of end-to-end transmission between BTS and a pair of Mobile stations. It is assumed that there is no direct link transmission between BTS and mobile stations due to high shadowing caused by obstacles or long distance between them. It is worth notifying that the end-to-end throughput achieved by one-way coded multicast scheme with diversity combining is better than two-way multicast scheme at low SNR values.

There exist two fundamental approaches to multicast routing namely minimum cost trees and shortest path trees. The (MCT’s) minimum cost tree is one which connects receiver and sources by providing a minimum number of transmissions (MNTs) the MNTs approach is generally used for energy constraint sensor and mobile ad hoc networks. In this paper we have considered node mobility and try to find out simulation based comparison of the (SPT’s) shortest path tree, (MST’s) minimum steiner trees and minimum number of transmission trees in wireless mesh networks by using the performance metrics like as an end to end delay, average jitter, throughput and packet delivery ratio, average unicast packet delivery ratio, etc. We have also evaluated multicast performance in the small and large wireless mesh networks. In case of multicast performance in the small networks we have found that when the traffic load is moderate or high the SPTs outperform the MSTs and MNTs in all cases. The SPTs have lowest end to end delay and average jitter in almost all cases. In case of multicast performance in the large network we have seen that the MSTs provide minimum total edge cost and minimum number of transmissions. We have also found that the one drawback of SPTs, when the group size is large and rate of multicast sending is high SPTs causes more packet losses to other flows as MCTs.

The users that take part in a video multicast session often have different bandwidth capabilities, and also experience different loss rates in the network. The process of delivering video to these receivers appropriate to their available bandwidth is called heterogeneous multicast. We present a solution for this problem based on the combination of multiple description coding and network coding. The receivers feed back information on the number of linearly independent descriptions that they obtain, and this is used to optimize the rate allocation of multiple descriptions. Our simulations show significant improvement in performance compared to unirate multicast that uses network coding. Unlike the case for unirate multicast, users with higher bandwidth receive higher quality video with MD/PNC.

New concepts of horizontal protection and half-mesh topology for survivability design in multicast optical virtual private networks are presented. All issues mentioned in this paper are expected to form targets for further investigations.

AS businesses become more dependent on IP networks, lots of real-time services are adopted and high availability in networks has become increasingly critical. With the development of carrier grade ethernet, the requirements of high speed metro ethernet device are more urgently. In order to reach the capacity of hundreds of Gbps or Tbps, most of core ethernet switches almost adopted distributed control architecture and large capacity forwarding fabric. When distributed switch works, they always have one CE and many FE. There for, it shows the feature of multicast with one sender and many receivers. It is deserved research for us how to apply reliable multicast to distributed switch inner communication system. In this paper, we present the general architecture of a distributed ethernet switch, focusing on analysis the model of internal communication subsystem. According to its character, a novel reliable multicast communication mechanism based on FEC recovery algorithm has been applied and evaluated in experiment.

The character of 1Gbps bandwidth and tree-based structure make EPON very suitable for broadcast or multicast services such as IPTV. The document proposed a novel scheme, based on the former research for controllable multicast over EPON system, mainly considering system security and maintainability. It can both control the IPTV program source's and the receiver's validity, improving the efficiency and precision. The processing of the two configurations mode is given in detail.

As multicast applications become more and more popular, implementing multicast in optical domain has attracted more and more attention due to its more efficient bandwidth usage. And also these services have Quality-of-Service (QoS) requirement. In this paper, the problem of cost-effective optical multicast provisioning to satisfy the differentiated leaf availability requirements is formally stated. A Mixed Integer Linear Program (MILP) formulation is proposed for provisioning dedicated light-tree protection with differentiated leaf availability guaranteed. The algorithm is so complex and infeasible that we also propose a feasible two-step approximate approach to solve the problem. Different from the previous schemes, our scheme finds out the primary light-trees and backup paths for multicast sessions destination nodes whose availability is not satisfied with the availability requirement. Because of taking the different leaf availability requirements into account, the proposed algorithm finds out more efficient feasible solution requiring less network resources.

The character of 1Gbps bandwidth and tree-based structure make EPON very suitable for broadcast or multicast services such as IPTV. In this paper we focus on security mechanisms that should be available to groups that specifically request it, and therefore are willing to pay the extra cost of implementing those mechanisms. We concentrate on two issues: how unauthorized multicast traffic can be prevented by means of multicast transit traffic control; how a group's susceptibility is likely to be reduced by means of multicast group access control. We have proposed a novel scheme that should be available to multicast groups that desire precautionary measures be taken to avert the threats of Invalid source and unauthorized access.

During the information era, the Internet and the service of World Wide Web develop rapidly. Therefore, the wider and wider bandwidth is required with the lower and lower cost. The demand of operation turns out to be diversified. Data, images, videos and other special transmission demands share the challenge and opportunity with the service providers. Simultaneously, the electrical equipment has approached their limit. So the optical communication based on the wavelength division multiplexing (WDM) and the optical cross-connects (OXCs) shows great potentials and brilliant future to build an optical network based on the unique technical advantage and multi-wavelength characteristic. In this paper, we propose a multi-layered graph model with inter-path between layers to solve the problem of multicast routing wavelength assignment (RWA) contemporarily by employing an efficient graph theoretic formulation. And at the same time, an efficient dynamic multicast algorithm named Distributed Message Copying Multicast (DMCM) mechanism is also proposed. The multicast tree with minimum hops can be constructed dynamically according to this proposed scheme.

The hierarchical multicast routing architecture in intelligent optical networks is investigated in this paper, the two methods of inter-domain information aggregation are given, and two hierarchical multicast routing algorithms are proposed. Their impacts on network performance in terms of blocking probability are evaluated by the simulations in different network models.

In this letter, aiming to obtain the best multicast performance of optical network in which the video conference information is carried by specified wavelength, we extend the solutions of matrix games with the network coding theory and devise a new method to solve the complex problems of multicast network switching. In addition, an experimental optical network has been testified with best switching strategies by employing the novel numerical solution designed with an effective way of genetic algorithm. The result shows that optimal solutions with genetic algorithm are accordance with the ones with the traditional fictitious play method.

How to improve the efficiency of key distribution is one of the emphases in the research area of satellite IP multicast networks in recent years. This paper presents a novel framework based on layered principle. This scheme divides original monolayer multicast key distribution structure into two layer, and makes rekeying modification happen only on its encapsulated individual group layer. A modified LKH based on member behavior activity is also proposed to decreases the amount of key update information transmission. So, this scheme can realize rapid rekeying by decreasing message transmission amount via satellite links and saving limited bandwidth resources, so as to provide significant performance gain for satellite multicast system. The simulation curves indicate that, compared with monolayer LKH mechanism in satellite multicast, our proposal is definitely advantageous in the condition of frequent join-leave, especially when the quantity of join member and leave member are about equal. So, it is concluded that the proposed key distribution scheme can provide scalability and high performance for large dynamic satellite multicast.

After analyzing the existing problems in real-time mission scheduling of satellite TT&C ground station, the live communication function of real-time scheduling speech fit for mission scheduling system in ground station is developed, using the IP multicast technology and multimedia speech processing technology, then the reliability of multicast is improved, and a network simulation test is made.

The Access Grid (AG) is a multi-party collaboration environment, where efficient media exchanges among remote participants are supported by IP multicast. However, due to limited availability of native IP multicast service, application-assisted multicast connectivity solutions are required in real operation of the AG. Recently, we have proposed a UMTP (UDP Multicast Tunneling Protocol) based solution, named as AG Connector, which takes advantage of UDP-based tunneling approach. In this paper, we extend this original AG Connector solution by addressing multiple UMTP server coordination and other operational issues. The proposed extended multicast connectivity solution can support increased number of AG nodes that even include nodes under NAT/Firewall-based private networks.

As to the traditional unicast and broadcast, multicast is also a kind of data transfer mode of IP network. Because multicast can save bandwidth, reduce network load, multicast is widely used on real time data transfer, video conferencing, distance education and Internet living broadcast. But multicast encounters more security challenges than unicast, such as unauthorized data sources and unauthenticated users. This paper discusses in detail about the multicast source control, multicast routing control and multicast user control. The main contribute of this paper is that a new multicast user control scheme is proposed and fully illustrated. And a whole mechanism to manage constrained-based multicast application is clearly described and implemented in this paper to achieve multicast source control, routing control and user control.

Because any link failure on the multicast session may disrupt the signal transmission to several downstream nodes, it is imperative to effectively protect the multicast sessions against link failure. In this paper, we study schemes for establishing primary and backup multicast trees for multicast sessions in a optical mesh network against link failure, e.g., fiber or conduit cut, with taking the different leaf availability requirement and availability guarantee into account. We propose an Mixed Integer Linear Program (MILP) approach to solve the problem of provisioning survivable multicast sessions with differentiated leaf availability guaranteed. Different from the previous schemes, our scheme finds out the complete (the tree spans the root and all the leaf nodes) primary and complete or incomplete (the tree spans the root and part of the leaf nodes) backup trees for multicast sessions guarantees the availability requirement. Because of taking the different leaf availability requirements into ccount, the proposed algorithm finds out more efficient feasible solution requiring less network resources, and even find a feasible solution where the previous algorithms fail.

IP multicast suffers from scalability problems when the number of simultaneously active multicast groups is very large. In this paper, we propose an algorithm called SGTM (Scalable Group-Tree Match algorithm) which reduces the number of trees by allowing several groups to be aggregated to the same delivery tree with controllable cost and introduce metrics to measure multicast state and tree management overhead for multicast schemes. SGTM performs faster aggregations than previous aggregation algorithms by evaluating fewer trees for each group, while keeping the same performance. We then show the scalability and the fastness of SGTM by several simulations and we compare its performance to the previous algorithm.

In this work, we present an effective overlay multicast tree constructing algorithm to meet delay constraint for real-time media service with the minimum networking price over Differentiated-Service networks. In addition, a dynamic and scalable tree maintaining algorithm is proposed for seamless service by updating the small parts of the tree when some End-systems join or leave the multicast group. An effective solution is obtained by changing the tree structure among Data-server, Proxy-senders and End-systems and the class vector of Proxy-senders. Finally, experimental results are presented to compare the performance of the proposed algorithm.

This paper addresses optimal multicast wavelength assignment problem in WDM network with limitedrange wavelength conversions (LWC). The optimal object of the problem is to minimize total number of LWCs required. We introduce the distortion constraint, which requires that the number of needed converters along the path from multicast source node to any member cannot be larger than the specified value. We solve the problem exactly by dynamic programming under session blocking policy and destination blocking policy, and present the experimental results.

Since IP-over-WDM has become a natural choice for the next generation backbone networks. It is more eminent to implement efficient multicast in WDM networks. A light-tree has been defined to support multicast sessions in WDM layer, it construct a point-to-multipoint light-paths from a source to multiple destinations and can be implemented by power-splitters. With the mature of power-splitters, there is a need to develop framework at higher layers to efficiently use the multicast available at WDM layer. In this paper, we concentrate on OBS-based multicast, new node models supporting WDM multicast are proposed. Then base on the models, we put forward novel implementation architecture of GMPLS-based OBS network to support multicast services, which maps an IP multicast-tree onto a multicast LSP that are connected to form a WDM light-tree. Two salient features of the architecture are: multicast LSP is constructed by data-driven; and the inter-operation between GMPLS framework and OBS. Finally, we discuss the performance of the proposed architecture.

The Access Grid (AG) provides collaboration environments over the IP multicast networks by enabling efficient exchange of multimedia contents among remote users; however, since lots of current networks are still multicast-disabled, it is not easy to deploy this multicast-based multi-party AG. For this problem, the AG provides multicast bridges as a solution by putting a relay server into the multicast networks. Multicast-disabled clients make UDP connections with this relay server and receives forwarded multicast traffics in unicast UDP packets. This solution is facing several limitations since it requires duplicate forwarding of the same packet for each unicast peer. Thus, in this paper, we propose an alternate solution for the multicast connectivity problem of the AG based on the UMTP (UDP multicast tunneling protocol). By taking advantage of flexibilities of UMTP, the proposed solution is designed to improve the efficiency of network and system utilization, to allow reuse of multicast-based AG applications without modification, and to partially address the NAT/firewall traversal issues. To verify the feasibility of proposed solution, we have implemented a prototype AG connectivity tool based on the UMTP, named as the AG Connector.

In this paper,architecture of grid audio/video communication environment based on optical layer multicast is introduced. First, architecture of optical layer multicast communication environment is analyzed. Then, scheme of large capability optical routing is presented. Last, condition of non-blocking multicast communication over WDM(wavelength division multiplexing) grid network is analyzed.

The paper discusses integrated QoS multicast routing and wavelength assignment algorithm in IP/DWDM Internet. Given a QoS multicast request with the bandwidth requirement, the multicast end-to-end delay and the delay variation bounds, we propose an algorithm, which can find a QoS-based multicast tree satisfying the above three constraints. The proposed algorithm constructs the multicast tree based on logical topology generated from physical topology. The logical topology is similar to the wavelength graph. Thus, the search process of the multicast tree means finding both route and available wavelength. By this way, the proposed algorithm integrates routing and wavelength assignment into a single process. We explain the correctness of the algorithm finally.

Recently there has been an increasing demand for providing multicasting service in mobile IP environment. However, it is still faced with great challenges, such as the established multicast delivery paths may frequently restructure when a node moves from one sub-network to another, incurring expensive overheads. This paper proposed a delay-constrained least-cost multicast routing algorithm to support multicast routing infrastructure for heterogeneous wire/wireless networks. The algorithm has three goals: (a) reduces the overall cost of the multicast tree, (b) reduces the join/leave latency when mobile node hand-off between wireless cells, (c) by using adaptive strategy, overcomes the shortcomings of traditional algorithms which deal with the cost and delay separately and needs lots of retrospect.

Multicasting is a natural paradigm for streaming live multimedia to multiple end receivers. Since IP multicast is not widely deployed, many application-layer multicast protocols have been proposed. However, all of these schemes focus on the construction of multicast trees, where a relatively small number of links carry the multicast streaming load, while the capacity of most of the other links in the overlay network remain unused. In this paper, we propose CodedStream , a high-bandwidth live media distribution system based on end-system overlay multicast. In CodedStream, we construct a k -redundant multicast graph (a directed acyclic graph) as the multicast topology, on which network coding is applied to work around bottlenecks. Simulation results have shown that the combination of k -redundant multicast graph and network coding may indeed bring significant benefits with respect to improving the quality of live media at the end receivers.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

As video conferencing and e-meeting systems are used more and more on the Internet and in businesses it becomes increasingly important to be able to participate from any computer at any location. Often this is impossible, since these systems requires often special software that are not available everywhere or impossible to install for administrative reasons. Many locations also lack the necessary network infrastructure such as IP multicast. This paper presents a WWW gateway system that enables users to participate using only a standard web browser. The design and architecture of the system are described and performance tests that show the scalability of the system are also presented.

In this work, we investigate the congestion control problem for layered video multicast in IP networks of active queue management (AQM) using a simple random early detection (RED) queue model. AQM support from networks improves the visual quality of video streaming but makes network adaptation more difficult for existing layered video multicast proticols that use the event-driven timer-based approach. We perform a simplified analysis on the response of the RED algorithm to burst traffic. The analysis shows that the primary problem lies in the weak correlation between the network feedback and the actual network congestion status when the RED queue is driven by burst traffic. Finally, a design guideline of the layered multicast protocol is proposed to overcome this problem.

In this paper, we address the problem of routing and wavelength assignment of multicast sessions with sub-wavelength traffic demands. We consider this problem in the scenario of WDM ring networks. In order to support multicasting, individual nodes need to have the capability to duplicate traffic. We consider two different node architectures which perform the duplication in optical and electronic domain, respectively. As traffic duplication at the electronic level is much more expensive than the optical alternative, we study the problem ofassigning routes and wavelengths to the multicast sessions so as to minimize electronic copying. The solutionto this problem can be divided into three phases - 1 . routingof multicast sessions, 2. construction of circles bygrouping non-overlapping arcs and 3. grouping these circles onto wavelengths. We propose a heuristic algorithmwhich implements the routing as well as circle construction phases simultaneously and then groups the circles. We present extensive simulation results to show that our approach leads to much lesser equipment cost than

To achieve scalable and efficient on-demand media distribution, existing solutions mainly make use of multicast as underlying data delivery support. However, due to the intrinsic conflict between the synchronous multicast transmission and the asynchronous nature of on-demand media delivery, these solutions either suffer from large playback delay or require clients to be capable of receiving multiple streams simultaneously and buffering large amount of data. Moreover, the limited and slow deployment of IP multicast hinders their application on the Internet. To address these problems, we propose asynchronous multicast, which is able to directly support on-demand data delivery. Asynchronous multicast is an application level solution. When it is deployed on a proxy network, stable and scalable media distribution can be achieved. In this paper, we focus on the problem of efficient media distribution. We first propose a temporal dependency model to formalize the temporal relations among asynchronous media requests. Based on this model, we propose the concept of Media Distribution Graph (MDG), which represents the dependencies among all asynchronous requests in the proxy network. Then we formulate the problem of efficient media distribution as finding Media Distribution Tree (MDT), which is the minimal spanning tree on MDG. Finally, we present our algorithm for MDT construction/maintenance. Through theoretical analysis and experimental study, we claim that our solution can meet the goals of scalability, efficiency and low access latency at the same time.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Multicast streaming has been extensively investigated to tackle the network bandwidth challenge. However, the ubiquitous deployment of IP multicast on the Internet is expected only after several years to come due to the manageability and scalability problems. We study a pragmatic solution to enhance the feasibility of multicast media streaming by focusing on an one-to-many streaming over the source specific multicast (SSM) service. In [1], we propose a synchronized multicast media streaming framework employing server-client coordinated adaptive playout. The adaptive playout mechanism controls the playout speed of audio and video by adopting the time-scale modification of audio. Based on the overall synchronization status as well as the buffer occupancy level, the playout speed of each client is manipulated within a perceptually tolerable range. In this work, we are extending the framework to incorporate the error recovery. Each client performs an interactive error recovery with the assistance of adaptive playout. RTCP-compatible signaling between the server and clients is performed, where the cumulative feedback for retransmission (to address the bandwidth restriction on the control messages) is assisted by the adaptive playout. The simulation results demonstrate several enhancements in terms of playout discontinuity and error recovery.

A key management approach of multicast is provided in this paper. It is based on the approach of assignment key to every group member through key center. In view of some management schemes where members join, leave or are deleted, key service center must distribute new key through unicast another time. The bigger amount of members the greater expenses will be spent. In this paper with member varying their upper key service center still distribute the new keythrough multicast and an ID is assigned to every member to identify their transmission message so as to implement data origin authentication. The essential principle of this approach is distributing a key generator for each member. For example a random number generator depending on certain algorithm can be distributed. And every member needs store a seed table. In this project key can automatically be renewed as time goes by or immediately renewed. Replace unicast by multicast to renew key decrease the spending. It is not only suitable for the key centralized management scheme with fewer members but also for the key separated management scheme with large group members and member frequently changed.

In reliable multicast communications, data packets are disseminated to all receivers in a multicast group. Generally, end-to-end congestion control adjusts transmission rate of the sender to the node of the lowest throughput in a multicast group. In this situation, when a multicast group includes receivers of significantly low throughput, lots of receivers suffer throughput degradation due to existence of low throughput nodes. This technical problem, called intra-session fairness, is special problem for multicast communications which include lots of receivers whose receiving capability is different in general. This paper proposes a new congestion control scheme for reliable multicast which improves intra-session fairness. A proposed scheme makes use of network support technology to enable a server in a network which includes low throughput receiver beneath it to behave as a pseudo receiver. A server stores arrived data packets and transmits them to receivers beneath it with adjusting transmission rate to the lowest throughput one. A server can hide existence of low throughput nodes to the sender, which enables improvement of intra-session fairness. Simulation results show that our proposed congestion control scheme improve intra-session fairness with increase of servers. We also show strategic arrangement of servers brings better improvement of intra-session fairness with small number of servers.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

QOS aware applications have propelled the development of two complementary technologies, Multicasting and Differentiated Services. To provide the required QOS on the Internet, either the bandwidth needs to be increased (Multicasting) or limited bandwidth prioritized among users (DiffServ). Although, the bandwidth on the Internet is continually increasing, the backbone is still insufficient to support QOS without resource allocations. Hence, there is a need to map multicasting in a DiffServ Environment to conserve network bandwidth and to provision this bandwidth in an appropriate fashion. In this regard, two issues have to be addressed. One, the key difference between multicast and DiffServe routing is the structure of the multicast tree. This tree is maintained in multicast aware routers whereas in DiffServe, the core routers maintain no state information regarding the flows. Second, the task of restructuring the multicast tree when members join/leave. Currently, the first issue is addressed by embedding the multicast information within the packet itself as an additional header field. In this paper, we propose a neural network based heuristic approach to address the second problem of routing in a dynamic DiffServe Multicast environment. Many dynamic multicast routing algorithms have been proposed. The greedy algorithm creates a near optimal tree when a node is added but requires many query/reply messages. The PSPT algorithm cannot construct a cost optimal tree. The VTDM algorithm requires the estimated number of nodes that will join and is not flexible. The problem of building an optimal tree to satisfy QOS requirements at minimum cost and taking minimum network resources is NP- complete and none of the above solutions give an optimal solution. We have modeled this combinatorial optimization as a nonlinear programming problem and trained an artificial neural network to solve the problem. The problem is tractable only when the QOS parameters are combined into DiffServe classes because of the flows are short-lived in dynamic multicasting. It has been shown that modification of the existing tree requires local search involving only a few nodes to determine to which existing node a newly added node should be connected. Simulation shows that the performance of this neural network based algorithm is superior in terms of cost and number of query messages in cases where the average multicast group size was large and the bias of the joining rate was close to one but performed poorly for small groups with respect to greedy algorithms. The cost of tree construction becomes independent of the group size when then the group size becomes larger than fifty or so.

This paper propose a new multicast protocol for ad hoc wireless networks. The scheme, named Partial Flooding, increases packet delivery ratio at high mobility speeds and high traffic rate, without increasing the control overhead. The basic principle is that, nodes will switch to flooding when link failures happen between nodes that are involved in the multicast process. At high mobility speeds link failures are expected to increase and increasing the frequency of updates is not always the ideal way. Our scheme is adaptive to high and low mobility speeds.

Optical multicast in a MPL(ambda)S network has not yet to be defined. An MPL(ambda)S network consists of lambda switching devices such as OXC. In this paper, optical multicast using the mixed waveband forwarding within a MPL(ambda)S network is discussed on both dense-mode and sparse-mode. And the OXC capable waveband switching is suggested. Unlike unicast routing, dense-mode multicast routing trees are established in a traffic-driven manner and it is not possible to topologically aggregate such trees, which are rooted at different sources. In sparse-mode multicast, source-specific trees may coexist with a core/shared trees, and it is not possible to assign a common wavelength label to traffic from different sources on a branch of the shared tree. This paper suggests a mixed waveband-forwarding scheme for supporting all two types of multicast (shared tree, source tree) routing trees in a MPL(ambda)S network.

The problem of assigning wavelengths and routing multicast sessions in DWDM networks has given rise to a host of heuristic and approximate techniques. In this paper we demonstrate that it is feasible to find optimal solutions for many instances of this problem using integer linear programming. The technique presented is also useful as an optimal standard to which heuristics can be compared in order to determine the quality of solutions they generate. The goal of this paper is to document an integer programming tableau for routing multicast sessions in DWDM networks, while accounting for a variety of limits on the abilities of the nodes in the network to drop, split and convert wavelengths. Examples of applying the tableau to problems of moderate size are included.

This paper describes a framework for the design of next generations of multicast services. The framework is based on active and programmable networks, distributed objects and distributed control algorithms with quality-of-service (QoS) constraints. Many of the Internet applications require variable (dynamic) QoS guarantees from networks. This is the case of distributed virtual environments that support the execution of simulation applications, or audio-video communication applications over the Internet. With the development of active and programmable networks, distributed object platforms and system technologies, it becomes feasible to provide multicast services that can be controlled to adapt the allocation of network resources to QoS variations. Multicast services based on the framework described in this paper can be used by application software components to manage network resources, to bring modifications to computations associated to network nodes, and to easily implement distributed control algorithms and services that can take into account variable QoS requirements expressed by applications. The paper focuses on the principles that govern the design and implementation of multicast protocols based on this framework, and the study of some of their major benefits. This work is partially supported by the European Commission - IST research program, under agreement IST-1999-10561: project FAIN.

In this paper, we evaluate the performance of several multicast schemes in optical burst-switched WDM networks taking into accounts the overheads due to control packets and guard bands (Gbs) of bursts on separate channels (wavelengths). A straightforward scheme is called Separate Multicasting (S-MCAST) where each source node constructs separate bursts for its multicast (per each multicast session) and unicast traffic. To reduce the overhead due to Gbs (and control packets), one may piggyback the multicast traffic in bursts containing unicast traffic using a scheme called Multiple Unicasting (M-UCAST). The third scheme is called Tree-Shared Multicasting (TS-MCAST) wehreby multicast traffic belonging to multiple multicast sesions can be mixed together in a burst, which is delivered via a shared multicast tree. In [1], we have evaluated several multicast schemes with static sessions at the flow level. In this paper, we perform a simple analysis for the multicast schemes and evaluate the performance of three multicast schemes, focusing on the case with dynamic sessions in terms of the link utilization, bandwidth consumption, blocking (loss) probability, goodput and the processing loads.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Within a few years, the number of live audio and video programs available on the Internet will increase dramatically. As the INternet grows as an entertainment medium, content providers are eager to access ratings information to know better what people are interested in and be able to personalize the programs. However, whereas it is easy to know how many people have connected to a given Web site, gathering rating about what multicast viewers are watching does not scale, because there could potentially by millions of viewers connected to a multicast group. This paper presents a novel scheme at the application level to gather feedback form multicast receivers in a scalable way. Our model based on the random sampling of receivers, scale well for very large group since we only need partial feedback to estimate the ratings.

In this paper, we present a new Internet multicast routing architecture and protocol called Adaptive Source and CORe based multicasT (ASCORT). ASCORT is designed with the objective of flexibly balancing the scalability and end-to- end performance. Unlike the core-based approach, all the distributions trees in ASCORT are source-specific. As a result, ASCORT has a better end-to-end performance than the core-based approach by being adaptive to the sources' location distributions. On the other hand, the tree nodes are not required to keep routing states for all the sources, thus resulting in a better scalability performance than the source-specific approach. In this paper we will provide an overview of ASCORT's approach and two protocols to convert a forest of independent source-specific trees to a forest of ASCORT source-specific distribution trees. We will also present preliminary simulation result to compare ASCORT's performance with the core-based and source-specific approaches.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The prevailing Internet has brought many novel network applications. These applications often involvethe interactions among multiple members in a single session. For example, the images and voices of thelecturer in distance learning must be transmitted to multiple destinations at the same time on demand. The status and opinions of any participant should also be transmitted to each other in a video conferencing for the interactivity of conversations.Without suitable protocol supports from the underlying networks, these applications may be costlyand infeasible. One of the important protocol supports is the capability of multicasting, sending a singledata packet to a set of receivers that are members of a multicast group. In the past, there are four well-known Internet multicast routing protocols: DVMRP (Distance Vector Multicast Routing Protocol), MOSPF (Multicast extensions to Open Shortest Path First), CBT (Core-Based Tree), and PIM (Protocol Independent Multicast). In this paper, we examine the four protocols in detail. Then wepropose several directions for performance improvement.Keywords: Multicast, Multicast Routing Protocols, Internet

The efficient support of the IP Integrated Services architecture (IIS) in ATM networks is nowadays a challenging research topic in the internetworking area. The integration of the two architectures needs the overcoming of the inconsistencies existing between their service models, in particular when considering multicast communications. The IIS architecture is based on the Resource Reservation Protocol (RSVP). IP multicast and RSVP rely on a receiver- oriented mode, where a receiver is not only capable of deciding whether to join or leave a multicast sessions, but it is also allowed to choose the associated QoS independently from the other participants. On the other hand, the ATM service model is sender-oriented: the originating node of a multipoint session is the only entity allowed to add or delete leaf nodes. In addition, the originating node sets the QoS of a session, which is unique for all the receivers. The IETF standard for IP multicast over ATM is the MARS model. Nevertheless this approach has been developed for best effort connections only. In this paper we present an extension to the MARS protocol n order to be integrated with the RSVP protocol for supporting QoS management. Within a logical IP Subnet, a Multicast Integration Server (MIS) is entitled of IP multicast address to ATM addressees resolution using the MARS protocol, and of QoS management using RSVP. In addition to the functionalities foreseen by the MARS specification, the MARS server within the MIS uses anew set of messages to inform the sender to a group about the QoS chosen by each receiver. An RSVP entity within the MIS is used to distribute RSVP messages within the LIS and to provide to the MARS the translation of the QoS level form IIS to ATM.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Many multicast ATM switch architectures have been proposed which differ greatly in the method in which replication of cells is handled. Depending on the switch architecture, the processing overhead incurred due to the cell copy function may be non-negligible. We develop a queuing model for a multicast switching node which accounts for this overhead. In the model, the source sends some number of duplicate cells, each of which is replicated at the switch to yield the total number of required copies. We use constrained optimization to determine the optimal amount of source duplication which minimizes the mean response time of the system. It is found that higher resource duplication is favored when the copy function overhead is comparable to the service time of a single cell. The model is then enhanced to account for errors and retransmission for reliable multicast.

In this paper, we study the multicast routing problem in broadband networks. The multicast routing problem, also known as the Steiner tree problem, has been well studied in the literature. However, less attention has been made for the definition of link costs and evaluating the performance of multicast routing algorithm from the network revenue point of view. Therefore, in this paper, we examined three approaches for defining link costs, namely, the Markov Decision Process-based (MDP), the Competitive On-Line (COL) routing-based and the linear-based approaches. Two heuristic multicast algorithms, TMR and MSPF. were developed for investigating the performance of these approaches. We proposed a new performance metric, referred to as the fractional reward loss, to evaluate the multicast routing algorithm. Performance of the multicast algorithms under different link cost functions was evaluated via simulations on a 20-node random graph. Our simulation results indicated that the way of defining link costs affects the performance of the multicast routing algorithms significantly and the best performance is yielded when using the MDP-based link costs.

A Cooperative Reliable Multicast Protocol (CRMP) has been developed to improve real-time data transmission onthe Internet Multicast Backbone (MBone) by adding a retransmit server and some repair servers to the multicastsession in order to recover lost packets. This paper describes a design and implementation of CRMP with Localrecovery (L-CRMP), an extension to the original CRMP. In L-CRMP, each repair server can work as a local serverthat retransmits packets to other repair servers that do not receive them from the source. Our goal in L-CRMP is toreduce the network overhead caused by retransmission packets while keeping the effective loss rate at the receiversapproximately the same.Keywords: MBone, Reliable Multicast, Local recovery 1. INTRODUCTION Real-time multicast applications are transmitted over the Internet through MBone (Multicast Backbone), a logicalnetwork running on top of the IP layer.1'2 Many of them, such as vat (Visual Audio Tool) or nv (Network Video),are based on RTP (Real-time Protocol) that does not support reliability. These applications may often experiencepoor quality due to large packet loss.3'4 A protocol, Cooperative Reliable Multicast Protocol (CRMP), is proposedin reference5 to alleviate the problem. A unique feature of CRMP is that it can be used with the current MBoneapplications without changing the operation of the source or receivers. Receivers that participate in CRMP coexistwith those that do not, but enjoys a better quality.Most reliable multicast protocols are designed for data transmission which requires perfect reliability but isresilient to delay, e.g.,6'7 and references therein. CRMP is however designed for real-time applications and exploitsthe fact that they do not require perfect reliability and, due to their stream nature, do not need acknowledgementfor every packet. In a large heterogeneous network, the delay between the retransmit server and some of the repairservers may be excessive. This motivates our extension of the original CRMP to include local recovery. It exploitsthe fact that loss at different repair servers is not synchronized, and therefore, a retransmission request of a repairserver may be fulfilled by a nearby repair server that has received the packet. In this paper we present a designand implementation of CRMP with local recovery (L—CRMP), and evaluate its performance. In addition to local

In this paper, we discuss issues of rate controlling many- to-many multicast connections. In particular, we present an end to end rate control algorithm for multicast ABR service in ATM networks. The algorithm is the extension of the SP- MRCA point-to-multicast congestion control algorithm proposed. The goal is to control the various multicast members input rates in order to achieve high bandwidth utilization without overflowing any queue along a multicast tree. We show that a multipoint-to-multipoint multicast connection can be viewed as a superposition of one-to-many multicast connections, and compute the multicast input rate for each multicast member separately. The algorithm proposed, called SP-MMRCA, inherits many of the properties of the point-to-multipoint SP-MRCA.

Rate allocation using the Max-Min fairness criterion may highly discriminate against multicast and long unicast sessions and may lead to sever network underutilization. In this paper, we present a solution for rate allocation that is based on competitive pricing. The resultant allocation increases fairness towards multicast sessions and improves network utilization considerably. The solution requires no re-routing of sessions. The economy on which we base our solution is simple enough, enabling its implementation for practical use. We present a distributed asynchronous protocol suitable for the ATM ABR service, which achieves the economy's allocation efficiently and with short convergence time.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The main problem complicating multicast video transport is variation in network bandwidth constraints. This paper presents a novel credit-based multicast flow control approach, which allows for potentially full utilization of all branches in a multicast tree at the expense of low priority packets losses. It uses hop-by-hop flow control as well as explicit rate congestion feedback from the destinations. The responsiveness, bandwidth utilization, video quality and fairness of the mechanism are evaluated through simulations. Results suggest that the proposed mechanism is capable of providing a high quality video service in the presence of varying bandwidth constraints.