Layered multicast congestion control by particle swarm optimization in heterogeneous environment

To enhance multicast throughput in heterogeneous environment,a new layered multicast congestion control scheme is proposed.With the goal of maximizing global satisfaction of the whole group,allocating sending rate in each layer is formulated to an optimization problem.Since the problem is noncovexity,the sender uses particle swarm optimization to search a set of optimal layers rates.The new scheme also eliminates ’lowest-first’ phenomenon by proposing a feedbacks suppression algorithm named equal-probability sampling (EPS).Upon EPS all the receivers send feedbacks at equal probability without bias.Simulation results prove that the new scheme can enhance global satisfaction and multicast throughput efficiently,compared with the traditional layered multicast congestion control scheme based on representatives.     

Layered media multicast control (LMMC): rate allocation and partitioning

The objective of layering techniques of distributing multimedia traffic over multicast IP networks is to effectively cope with the challenges in continuous media applications. The challenges include heterogeneity, fairness, real-time constraints, and quality of service. We study the problem of rate allocation and receiver partitioning in layered and replicated media systems. We formulate an optimization problem aimed at maximizing a close approximation of the so-called max-min fairness metric subject to loss and bandwidth constraints. Our optimal layered media multicast control (LMMC) solution to the problem analytically determines the layer rates and the corresponding partitioning of the receivers. Our simulation results show the effectiveness of our proposed solution in realistic scenarios.     

Fine-grained polysilicon films with built-in tensile strain

Novel processing conditions and strain diagnostic structures are used to demonstrate that polysilicon films with built-in tensile-strain can be achieved and that any physical size limitations due to compressive-buckling in polysilicon micromechanical structures can be eliminated     

Reliable multicast with delay guarantees

The reliable multicast protocol guarantees that all receivers place the source messages in the same order. We have changed this protocol from an event-driven protocol to a timed protocol in order to also guarantee that all of the receivers have a source message by a deadline. Certain of the control messages that are transmitted by the receivers in this protocol are scheduled to occur at specified times, rather than responding to other messages. This results in short sequences of protocol states that are independent of one another, rather than a protocol machine that is recursive and runs indefinitely. It is easier to prove the properties of these short sequences of events than to prove those of many protocols that have indefinitely long sequences     

Scalable reliable multicast using multiple multicast channels

We examine an approach for providing reliable, scalable multicast communication, involving the use of multiple multicast channels for reducing receiver processing costs and reducing network bandwidth consumption in a multicast session. In this approach a single multicast channel is used for the original transmission of packets. Retransmissions of packets are done on separate multicast channels, which receivers dynamically join and leave. We first show that protocols using an infinite number of multicast channels incur much less processing overhead at the receivers compared to protocols that use only a single multicast channel. This is due to the fact that receivers do not receive retransmissions of packets they have already received correctly. Next, we derive the number of unwanted redundant packets at a receiver due to using only a finite number of multicast channels, for a specific negative acknowledgment (NAK)-based protocol. We then explore the minimum number of multicast channels required to keep the cost of processing unwanted packets to a sufficiently low value. For an application consisting of a single sender transmitting reliably to many receivers we find that only a small number of multicast channels are required for a wide range of system parameters. In the case of an application where all participants simultaneously act as both senders and receivers a moderate number of multicast channels is needed. Finally, we present two mechanisms for implementing multiple multicast channels, one using multiple IP multicast groups and the other using additional router support for selective packet forwarding. We discuss the impact of both mechanisms on performance in terms of end-host and network resources     

Fine-grained cooperative access control scheme with hidden policies

The traditional ciphertext policy attribute-based encryption (CP-ABE) has two problems:one is that the access policy must be embedded in the ciphertext and sent, which leads to the disclosure of user爷 s privacy information, the other is that it does not support collaborative decryption, which cannot meet the actual demand of conditional collaborative decryption among multiple users. In order to deal with the above two problems at the same time, a fine-grained cooperative access control scheme with hidden policies (FCAC-HP) is proposed based on the existing CP-ABE schemes combined with blockchain technology. In FCAC-HP scheme, users are grouped by group identifier so that only users within the same group can cooperate. In the data encryption stage, the access policy is encrypted and then embedded in the ciphertext to protect the privacy information of the access policy. In the data access stage, the anonymous attribute matching technology is introduced so that only matched users can decrypt ciphertext data to improve the efficiency of the system. In this process, a smart contract is used to execute the verification algorithm to ensure the credibility of the results. In terms of security, FCAC-HP scheme is based on the prime subgroup discriminative assumption and is proved to be indistinguishable under chosen plaintext attack (CPA) by dual system encryption technology. Experimental verification and analysis show that FCAC-HP scheme improves computational efficiency while implementing complex functions.     

Online multicast routing with bandwidth guarantees: a new approach using multicast network flow

We present a new algorithm for online routing of bandwidth-guaranteed multicasts where routing requests arrive one by one without any prior knowledge of future requests. A multicast routing request consists of a source, a set of receivers, and a bandwidth requirement. Two multicast applications of interest are routing of point-to-multipoint label-switched paths in multiprotocol label switched (MPLS) networks, and the provision of bandwidth-guaranteed virtual private network (VPN) services under the "hose" service model. Without prior knowledge of multicast requests, offline multicast routing algorithms cannot be used. Online algorithms are needed to handle requests arriving one by one and to satisfy as many potential future demands as possible. Our new online algorithm is based on the idea that a newly routed multicast must follow a route that does not interfere too much with network paths that may be critical to satisfy future demands. We develop a multicast tree selection heuristic based on the idea of deferred loading of certain critical links. The algorithm identifies them as links that, if heavily loaded, would make it impossible to satisfy future demands between certain ingress-egress pairs. The algorithm uses link-state information and some auxiliary capacity information for multicast tree selection and is amenable to distributed implementation. Unlike previous algorithms, our algorithm exploits any available knowledge of the network ingress-egress points of potential future demands, even though the demands themselves are unknown. It performs very well.     

QoS multicast routing with delay constraints

Proliferation of group-based real-time applications, such as online games and video conferencing has motivated research into QoS multicast routing. These types of applications require consideration of both source-to-destination delay (i.e., packet delay from the source to all destinations) and inter-destination delay variation (i.e., the difference in packet delay from the source to different destinations) constraints. In this paper, we formulate a new combined problem for delay partitioning and multicast routing with source-to-destination delay and inter-destination delay variation constraints in a QoS framework, where a delay dependent cost function is associated with each network link. After identifying the problem asnp-complete, we introduce a Genetic Algorithm (ga) based algorithm that computes a source-based multicast tree which satisfies both constraints with near-optimal cost. We compare differentga schemes using different selection operators and find that the combination of Steady Statega and Remainder Stochastic Sampling selection operator works best for our problem. Simulation results also show that ourga heuristic consistently perfornis better than several other simple heuristics.     

Adaptive group multicast with time-driven priority

This paper shows how to provide an adaptive real-time group multicast (many-to-many) communication service. Adaptive means that the number of nodes that transmit to the multicast group is continuously changing. In order to meet deterministic quality-of-service (QoS) requirements of a real-time group multicast, some communication resources are reserved. We show (1) how bandwidth is reserved for each multicast group and (2) how an active source can dynamically share the bandwidth allocated to this multicast group with other active group members. Quality-of-service support for a real-time multicast group is based on time-driven priority. In this scheme the time is divided into time frames of fixed duration, and all the time frames are aligned by using a common global time reference, which can be obtained from the Global Positioning System. Bandwidth is allocated to a multicast group as a whole, rather than individually to each user. The allocation is done by reserving time intervals within time frames in a periodic fashion. This type of allocation raises two problems that are studied in this paper: (1) scheduling: how time intervals are reserved to each multicast group and (2) adaptive sharing: how the active (transmitting) participants can dynamically share the time intervals that have been reserved for their multicast group. The proposed approach is based on the embedding of multiple virtual rings, one for each multicast group. By using the virtual rings, it is simple to route messages to all the participants while minimizing the bound on the buffer sizes and queueing delays. The final part of this paper introduces a scalable growth of the multicast group by adding multiple subtrees to the virtual ring     

高稳定的可扩展覆盖网多播算法

提出了一种高稳定的可扩展覆盖网多播（SOM-HS, scalable overlay multicast with high stability）算法。SOM-HS算法定义了节点稳定度因子以及链路权重,能保证高稳定的节点位于多播树骨干网中。在分层分簇构造过程中,SOM-HS算法限制节点出度,保证节点负载均衡。实验结论表明,与现有其他算法相比,在不同组规模下,使用SOM-HS算法时的最大多播延时都最小。     

Design differentiated service multicast with selfish agents

Differentiated service (DiffServ) is a mechanism to provide the quality-of-service (QoS) with a certain performance guarantee. In this paper, we study how to design DiffServ multicast when every relay link is an independent selfish agent. We assume that each link e/sub i/ is associated with a (privately known) cost coefficient c/sub i/ such that the cost of e/sub i/ to provide a transmission service with bandwidth demand x is c/sub i//spl middot/x. Further, we assume that there is a fixed source node s and a set R of receivers, each of which requires from s data with a minimum bandwidth demand. The DiffServ multicast problem is to compute a link-weighted tree rooted at s and spanning R such that the receivers' demands are met. This generalizes the traditional link-weighted Steiner tree problem. We first show that a previous approximation algorithm does not directly induce a strategyproof mechanism. We then give a new polynomial time algorithm to construct a DiffServ multicast tree whose total cost is no more than eight times the optimal total cost when the cost coefficient of each link is known. Based on this tree, we design a truthful mechanism for DiffServ multicast, i.e., we give a polynomial-time computable payment scheme to compensate all chosen relay links such that each link maximizes its profit when it declares its cost coefficient truthfully.     

Dynamic group multicast routing with bandwidth reservations

Multicasting refers to the transmission of data from a source node to multiple destination nodes in a network. Group multicasting is a generalization of multicasting whereby every member of a group is allowed to multicast messages to other members that belong to the same group. The routing problem in this case involves the construction of a set of low cost multicast trees with bandwidth requirements, one for each member of the group for multicasting messages to other members of the group. In this paper, we examine this routing problem with an additional requirement that member nodes are allowed to join and leave the multicasting group anytime during a session. We call this problem, the dynamic group multicast routing problem (DGMRP). In this paper, we proposed three heuristic algorithms to generate a set of low cost multicast trees with dynamic group membership. Results from our empirical study shows that the one of the proposed algorithms, called Maximum bandwidth bottleneck path selection algorithm (MBBPS), achieves better utilization of bandwidth resources as compared with the other two algorithms which are based on a greedy approach. In addition MBBPS performs better in terms of cost when the bandwidth is not sufficient in the network. Copyright © 2002 John Wiley & Sons, Ltd.     

利用组播树优化VPLS组播功能的研究

RFCs 4761和4762描述了一种基于利用点对点或点对多点单播LSP承载组播流量的VPLS解决方案.对于某些VPLS组播流量配置,这种解决方案有一定局限性.例如,当有大量的组播流量需要传播时,会导致带宽利用严重非最佳化.本文描述的解决方案是为了克服现有VPLS组播解决方案中的一部分局限性.其中描述了在SP网络中利用组播树来实现VPLS组播的过程.该解决方案允许在多个VPLS实例间共享一个这样一棵组播树.此外,本文提出的解决方案还允许SP网络中的一棵单独的组播树承载来自一个或多个VPLS实例的,仅仅属于指定的一个或多个IP组播流集合的流量.     

Stateless overlay multicast with in-packet bloom filters

Due to the difficulty of deploying Internet protocol (IP) multicast on the Internet on a large scale, overlay multicast has been considered as a promising alternative to develop the multicast communication in recent years. However, the existing overlay multicast solutions suffer from high costs to maintain the state information of nodes in the multicast forwarding tree. A stateless overlay multicast scheme is proposed, in which the multicast routing information is encoded by a bloom filter (BF) and encapsulated into the packet header without any need for maintaining the multicast forwarding tree. Our scheme leverages the node heterogeneity and proximity information in the physical topology and hierarchically constructs the transit-stub overlay topology by assigning geometric coordinates to all overlay nodes. More importantly, the scheme uses BF technology to identify the nodes and links of the multicast forwarding tree, which improves the forwarding efficiency and decreases the false-positive forwarding loop. The analytical and simulation results show that the proposal can achieve high forwarding efficiency and good scalability.     

Performance assessment of multicast node placement for multicast routing in WDM networks with sparse light splitting

This article examines all-optical multicast routing for wavelength-routed optical networks with sparse Multicast Capable (MC) nodes in two phases. The first phase is MC node placement and use of a simple and straightforward Maximum Path Count First (MPCF) algorithm to obtain candidates for MC nodes. The second phase is multicast routing with MC-based schemes that minimizes the number of wavelength channels with minimum transmission delay as required by a given multicast session, in that a light-tree is first constructed to connect MC nodes in a multicast group by using two algorithms, namely, the Pre-computing Minimum Cost (PMC) tree algorithm and the Pre-computing Shortest Path (PSP) tree algorithm. System performance of the proposed MPCF MC node placement algorithm is compared with that of the Normalized Cuts (NC) MC node placement algorithm for both PMC and PSP multicast routing. Furthermore, simulation results compare PMC and PSP multicast routing based on MPCF and NC node placement with Re-route-to-Source (RTS), Re-route-to-Any (RTA), Member-First (MF), and Member-Only (MO) multicast routing based on a light forest for a given multicast session in terms of average number of wavelengths needed, average blocking probability, and mean maximum transmission delay.

A secure multicast protocol for the internet's multicast backbone

In this paper we propose a secure and efficient multicast protocol where the key management is distributed to local groups. The proposed protocol takes advantage of MBone topology to maintain scalability and efficiency at the same time. Copyright © 2001 John Wiley & Sons, Ltd.     

Rearrangeability of multicast Clos networks with middle-stage fan-out

The sufficient and necessary conditions under which a three-stage Clos network is rearrangeable for multicast connections are given. It is assumed that only switches of the middle stage have the fan-out property. Such an assumption is valid for some practical switching systems, e.g., high-speed crossconnects.     

利用FDL实现OBS网络中的组播业务

本文给出了一种OBS网络中组播业务的实现机制。它利用由光分路器和光纤延迟线（FDL）构成的组播功能模块实现了组播数据包在多分支节点处的复制、存储以及转发。仿真分析结果表明，该机制可以通过引入一定的时延，大幅降低丢包率。     

Admission control algorithms for multicast sessions with multiplestreams

Real-time multicast communication is considered, in which each destination makes an individual bid for delivery of a subset of real-time hierarchically encoded streams that are offered to the session by the source. The objective is to customize stream delivery to destinations, based on their requests and network constraints. Admission control procedures, which consider requests for multiple streams from multiple destinations and resolve contention when users' requests exceed available network resources, are presented. Specifications for four admission control procedures are presented and their properties analyzed. A performance measure for admission control is defined to be the total gain for the source that equals the sum of bids by the users taking delivery of the streams they ordered. Simulation results of the performance of the procedures are presented and compared to the performance of an optimal, but highly complex, admission control algorithm. In this paper the assumption is that the routing tree is already in place and the focus is on managing users' requests and deciding on which stream to deliver to each destination. This is done by signaling protocols that transfer messages containing users' requests and resource allocation commands between a source and the destinations. In addition, admission control protocols take users' requests and network resources as their input and issue as outputs the decisions on which request to admit (and allocate resources for) and which to reject