A high-performance input access scheme for ATM multicast switching

In this paper, we propose an input access scheme for input-queued ATM multicast switches, achieving high system throughput, low packet delay and packet loss probability. Multicast and unicast packets of each input port are separately queued. Multicast queues take priority over the unicast queues, and both types of queues are fairly served in a cyclic-priority access discipline. In particular, each unicast queue is handled on a window-service basis, and each multicast packet is switched in a one-shot scheduling manner. To evaluate the performance of the access scheme, we propose an approximate analysis based on a simplified cyclic-priority model for anN×N finite-buffer multicast switch possessing Bernoulli multicast and unicast arrivals, with window-service (for unicasting) and one-shot scheduling (for multicasting) both taken into account. Finally, we show simulation results to demonstrate the accuracy of the approximate analysis and the superiority of the scheme over existing schemes with respect to normalized system throughput, mean packet delay, and packet loss probability.An earlier version of this paper appeared in IEEE ICC'96.     

Efficient support of IP multicast in the next generation of GEO Satellites

Satellites are expected to have an important role in providing the Internet protocol (IP) multicast service to complementing next-generation terrestrial networks. In this paper, we focus on the deployment of IP multicast over the next generation of digital video broadcasting-based geosynchronous earth orbit satellites supporting multiple spot beams and on-board switching technologies. We propose a new encapsulation scheme optimized for IP multicast, which has two distinct modes enabling two alternative on-board switching approaches: the self-switching and the label-switching. We also detail a set of mechanisms and protocols for ground stations, as well as for the on-board processor to allow an efficient multicast forwarding in this type of environment, while reducing the load of control and data messages in the satellite segment, and building efficient multicast delivery trees reaching only the spot beams containing at least one member of the corresponding multicast session. To integrate satellite links in the terrestrial Internet, we present satellite multicast adaptation protocol (SMAP), a protocol which is implemented in satellite stations to process incoming protocol independent multicast-sparse mode (PIM-SM) messages sent by terrestrial nodes to the satellite system. SMAP helps to update the tables required for the mapping between IP packets and MPEG-2 data segments, their switching on board the satellite, and their filtering at the satellite receivers.     

基于IPV6的组播路由协议PIM-SM的研究及实现

文章首先分析了研究IPv6组播技术的重要意义.然后详细分析了组播路由协议PIM-SM,并且在实验室生成IPv6环境下,对PIM-SM协议中的BSR选举、RP竞争、HelIo消息发布和数据流树切换等进行了测试,测试结果表明该协议工作正常,以其为基础实现的组播系统是正确的,符合RFC相关文档说明.     

AuthFlow: authentication and access control mechanism for software defined networking

Software-defined networking (SDN) is being widely adopted by enterprise networks, whereas providing security features in these next generation networks is a challenge. In this article, we present the main security threats in software-defined networking and we propose AuthFlow, an authentication and access control mechanism based on host credentials. The main contributions of our proposal are threefold: (i) a host authentication mechanism just above the MAC layer in an OpenFlow network, which guarantees a low overhead and ensures a fine-grained access control; (ii) a credential-based authentication to perform an access control according to the privilege level of each host, through mapping the host credentials to the set of flows that belongs to the host; (iii) a new framework for control applications, enabling software-defined network controllers to use the host identity as a new flow field to define forwarding rules. A prototype of the proposed mechanism was implemented on top of POX controller. The results show that AuthFlow denies the access of hosts either without valid credentials or with revoked authorization. Finally, we show that our scheme allows, for each host, different levels of access to network resources according to its credential.     

MobiCast: A multicast scheme for wireless networks

In this paper, we propose a multicast scheme known as MobiCast that is suitable for mobile hosts in an internetwork environment with small wireless cells. Our scheme adopts a hierarchical mobility management approach to isolate the mobility of the mobile hosts from the main multicast delivery tree. Each foreign domain has a domain foreign agent. We have simulated our scheme using the Network Simulator and the measurements show that our multicast scheme is effective in minimizing disruptions to a multicast session due to the handoffs of the mobile group member, as well as reducing packet loss when a mobile host crosses cell boundaries during a multicast session.     

基于主机性能评价的视频会议系统优化方案

组播技术的出现为基于P2P的视频会议系统提供了负载更小的开发方案,但在传统的组播技术支持下,分配到每台主机上的负载量依然可观。为解决突发负载问题,文中提出了一种基于主机性能评价的应用层组播算法,利用拓扑信息减少冗余数据在网络上传输,根据主机性能平衡负载分配,减轻主机负担。之后,在此组播算法之上,阐述了一种传统视频会议系统的优化实现方案。     

安全多播准入控制系统的研究与实现

安全问题一直是多播技术发展中一个亟待解决的问题,而在所有的安全问题中,安全多播准入控制是研究的焦点.研究了国内外现有的典型多播准入控制方案,对它们的优缺点进行了分析和比较研究.结合各种多播准入控制方案的优点,给出了一个基于IGMP协议的安全多播准入控制方案.实验表明该安全多播准入控制方案具有安全性高、稳定性好、扩展性好、易于迁移到IPv6环境和便于部署等特点,有较高的实际应用价值.     

An efficient heterogeneous key management approach for secure multicast communications in ad hoc networks

In a mobile wireless ad hoc network, mobile nodes cooperate to form a network without using any infrastructure such as access points or base stations. Instead, the mobile nodes forward packets for each other, allowing communication among nodes outside wireless transmission range. As the use of wireless networks increases, security in this domain becomes a very real concern. One fundamental aspect of providing confidentiality and authentication is key distribution. While public-key encryption has provided these properties historically, ad hoc networks are resource constrained and benefit from symmetric key encryption. In this paper, we propose a new key management mechanism to support secure group multicast communications in ad hoc networks. The scheme proposes a dynamic construction of hierarchical clusters based on a novel density function adapted to frequent topology changes. The presented mechanism ensures a fast and efficient key management with respect to the sequential 1 to n multicast service.     

One-to-many multicast restoration based on dynamic core-based selection algorithm in WDM mesh networks

This paper proposes a novel dynamic core-based selection (DCS) algorithm for the multicast restoration in WDM mesh networks. The core-based fault tolerance scheme provides a flexible way to control a number of core nodes with less control overheads for searching the routing path, wavelength assignment (RWA), and restoration paths when fault occurs in the one-to-many multicast domain. Compared with the source-based scheme, core-based schemes are easier to maintain, and specifically scalable in large-scale topologies. In the core-based fault tolerance scheme, k-tuple domination nodes are selected to form a minimum sized vertex subset such that each vertex in the graph is dominated by at least k vertices, where the k is defined as two in this paper. The proposed DCS algorithm is defined as each node in multicast tree session must be directly connected to at least one core node in multicast tree session and also has to be directly connected to at least one core node out of multicast tree session. The primary aim of this work is to provide the scalable and fast local survivability based on the information from core nodes. Simulation results show that the proposed algorithm outperforms the Dual Tree and MRLR algorithms in terms of total hop counts needed for all recovery paths and blocking probability for different network topologies.     

SECURE GROUP COMMUNICATIONS FOR LARGE DYNAMIC MULTICAST GROUP

As the major problem in multicast security, the group key management has been the focus of research. But few results are satisfactory. In this paper, the problems of group key management and access control for large dynamic multicast group have been researched and a solution based on SubGroup Secure Controllers (SGSCs) is presented, which selves many problems in IOLUS system and WGL scheme.     

Interference coordination schemes for cellular network assisted device-to-device multicast

In this paper, a multicast concept for device-to-device （D2D） communication underlaying a cellular infrastruc~tre is investigated. To increase the overall capacity and improve resource utilization, a novel interference coordination scheme is proposed. The proposed scheme includes two steps. First, in order to mitigate the interference from D2D multicast transmission to cellular networks （CNs）, a dynamic power control scheme is proposed that can determine the upper bound of D2D transmitter power based on the location of base station （BS） and areas of adjacent cells from the coverage area of D2D multicast group. Next, an interference limited area control scheme that reduces the interference from CNs to each D2D multicast receiver is proposed. The proposed scheme does not allow the coexistence of cellular user equipments （CUEs） located in the interference limited area to reuse the same resources as the D2D multicast group. From the simulation results, it is confirmed that the proposed schemes improve the performance of the hybrid system compared to the conventional ways.     

Explicit Multicast Extension (Xcast+) for Efficient Multicast Packet Delivery

In this letter, we propose a new multicast scheme, named Xcast+, which is an extension of Explicit Multicast (Xcast) for an efficient delivery of multicast packets. The mechanism incorporates the host group model and a new control plane into existing Xcast, and not only does it provide the transparency of traditional multicast schemes to senders and receivers, but it also enhances the routing efficiency in networks. Since intermediate routers do not have to maintain any multicast states, it results in a more efficient and scalable mechanism to deliver multicast packets. Our simulation results show distinct performance improvements of our approach compared to Xcast, particularly as the number of receivers in a subnet increases.     

OMAC: A new access control architecture for overlay multicast communications

Multicast communications concern the transfer of data among multiple users. Multicast communications can be provided at the network layer—an example is IP multicast—or at the application layer, also called overlay multicast. An important issue in multicast communications is to control how different users—senders, receivers, and delivery nodes—access the transmitted data as well as the network resources. Many researchers have proposed solutions addressing access control in IP multicast. However, little attention has been paid to overlay multicast. In this paper, we investigate the access control issues in overlay multicast and present OMAC: a new solution to address these issues. OMAC provides access control for senders, receivers, and delivery nodes in overlay multicast. The proposed architecture, which is based on symmetric key cryptosystem, centralizes the authentication process in one server whereas it distributes the authorization process among the delivery nodes. Moreover, delivery nodes are utilized as a buffer zone between end systems and the authentication server, making it less exposed to malicious end systems. To evaluate our work, we have used simulation to compare the performance of OMAC against previous solutions. Results of the simulation show that OMAC outperforms previous multicast access control schemes. Copyright © 2010 John Wiley & Sons, Ltd.     

Tree-shared multicast in optical burst-switched WDM networks

In this paper, we propose a new multicast scheme called tree-shared multicasting (TS-MCAST) in optical burst-switched wavelength-division-multiplexing networks, taking into consideration overheads due to control packets and guard bands (GBs) associated with data bursts. In TS-MCAST, multicast traffic belonging to multiple multicast sessions from the same source-edge node to possibly different destination-edge nodes can be multiplexed together in a data burst, which is delivered via a shared multicast tree. To support TS-MCAST, we propose three tree-sharing strategies based on equal coverage, super coverage, and overlapping coverage, and present a simple shared multicast tree-construction algorithm. For performance comparison, we consider two other multicast schemes: separate multicasting (S-MCAST) and multiple unicasting (M-UCAST). We show that TS-MCAST outperforms S-MCAST and M-UCAST in terms of bandwidth consumed and processing load (i.e., number of control packets) incurred for a given amount of multicast traffic under the same unicast traffic load with static multicast sessions and membership.     

A bandwidth-efficient and fair CSMA/TDMA based multichannel MAC scheme for V2V communications

Designing QoS-aware medium access control (MAC) scheme is a challenging issue in vehicular ad hoc networks. Proportional fairness and bandwidth utilization are among the significant requirements that should be taken into account by a MAC scheme. In this paper, a bandwidth-efficient and fair multichannel MAC protocol is proposed to address these two requirements, specifically in vehicle-to-vehicle communications. The proposed scheme is based on clustering of vehicles and exploits time division multiple access (TDMA) method alongside the carrier sense multiple access with collision avoidance mechanism to allocate DSRC-based resources in a different manner from IEEE 802.11p/IEEE 1609.4 protocols. It divides each channel into aligned dynamic-sized time frames. In each time frame, in a fully TDMA-based period, transmission opportunities are assigned to vehicles letting them have dedicated transmissions on the service and control channels. The maximum number of transmission opportunities per each frame is determined by the cluster head (CH) based on a defined optimization problem which aims at maximizing both proportional fairness and bandwidth utilization. Furthermore, the bandwidth utilization is assumed to be enhanced more through reallocation of unused transmission opportunities in each time frame, using a proposed reallocation algorithm. The proposed MAC protocol is treated as a lightweight scheme such that various types of unicast, multicast and broadcast communications are possible within the cluster without involving the CH. Evaluation results show that the proposed scheme has more than 90 % achievement in terms of proportional fairness and bandwidth utilization simultaneously, and in this case, has a considerable superiority over TC-MAC. In addition, using the proposed scheme, the satisfaction level of vehicles is preserved appropriately.     

IPv6网络中组播路由--PIM技术研究

随着网络宽带用户和下一代互联网的发展,多媒体业务相关服务如网络电视(IPTV)需求的日益增长刺激了IP组播技术的普及和发展,使其成为新一代网络中不可缺少的关键技术.与单播应用相比,采用IP组播技术分发信息常常能从本质上减少整个网络对带宽的需求.文章从IPv6网络的各种组播技术入手,详细介绍了当前在实际网络中获得广泛应用的基于协议无关组播(PIM)的组播路由技术 ,重点介绍了域内组播路由中使用最广泛的PIM稀疏模式(PIM-SM).对整个PIM-SM组播路由协议在IPv6网络中的运行过程进行了论述,最后介绍了其在未来IPTV等网络应用中的前景.     

A dynamic location management service for group applications in cellular networks

To cope with the increasing demand of multimedia applications, new IEEE 802.11 wireless local area networks devices have been defined such as IEEE 802.11aa and IEEE 802.11ac. The former proposes new intra-access categories (AC) differentiation based on stream classification service (SCS) scheme. The latter standard allows simultaneous downlink transmissions thanks to downlink multi-user MIMO technology and sharing transmission opportunity (TXOP) period scheme. In this paper, we focus on the basis of this technique and the behavior of the access point (AP) to manage the multi-user access. Then, we propose a hybrid access mechanism entitled multi-user multi-cast access mechanism (MUMAM) that supports downlink multi-user transmissions while considering intra-AC differentiation. MUMAN considers SCS scheme to prioritize between multicast and unicast flows of an AC and follows transmissions based on IEEE 802.11ac TXOP sharing technique. Extensive simulation and analysis show that MUMAM has a significant positive impact on delay and throughput performance of different AC(s).     

Distributed Mapping Management of Identifiers and Locators in LISP-based Mobile Networks

The Locator Identifier Separation Protocol (LISP) has been proposed as an identifier-locator separation scheme for scalable Internet routing. However, LISP was originally designed in the fixed network environment rather than in the mobile network environment. In particular, the existing LISP mobility schemes are based on a centralized map server that is used as an anchor point for mobile nodes, and thus intrinsically subject to some limitations in mobile environment. In this paper, we propose a distributed mapping management of Endpoint Identifiers (EIDs) and Locators (LOCs) in mobile LISP networks. We use Routing LOC (RLOC) and Local LOC (LLOC) as locators for mobile hosts. RLOC represents the IP address of the domain gateway, and LLOC is the IP address of the access router that a host is currently attached to. For EID-LOC mapping management, each network domain has a Distributed Map Server (DMS) over its gateway. Each DMS keeps track of the EID-LOC mapping information for mobile hosts in the distributed way. The proposed scheme is also a network-based approach, in which each access router, instead of a host, performs the mapping management operations. From the performance analysis, we can see that the proposed distributed scheme can give better performance than the existing schemes in terms of the signaling delays required for EID-LOC mapping update and query operations.     

IP组播的安全解决方案

简单介绍了IP组播的基本网络体系和潜在的应用,PIM-SM组播基本原理和特点,阐述了在实际的PIM-SM网络中一系列组播安全控制手段,包括防止RP欺骗、SA消息控制、组播发送授权控制、数据的安全性控制、用户安全认证等措施。