An Efficient Multicast Routing Protocol in Wireless Mobile Networks

Providing multicast service to mobile hosts in wireless mobile networking environments is difficult due to frequent changes of mobile host location and group membership. If a conventional multicast routing protocol is used in wireless mobile networks, several problems may be experienced since existing multicast routing protocols assume static hosts when they construct the multicast delivery tree. To overcome the problems, several multicast routing protocols for mobile hosts have been proposed. Although the protocols solve several problems inherent in multicast routing proposals for static hosts, they still have problems such as non-optimal delivery path, datagram duplication, overheads resulting from frequent reconstruction of a multicast tree, etc. In this paper, we summarize these problems of multicast routing protocols and propose an efficient multicast routing protocol based on IEFT mobile IP in wireless mobile networks. The proposed protocol introduces a multicast agent, where a mobile host receives a tunneled multicast datagram from a multicast agent located in a network close to it or directly from the multicast router in the current network. While receiving a tunneled multicast datagram from a remote multicast agent, the local multicast agent may start multicast join process, which makes the multicast delivery route optimal. The proposed protocol reduces data delivery path length and decreases the amount of duplicate copies of multicast datagrams. We examined and compared the performance of the proposed protocol and existing protocols by simulation under various environments and we got an improved performance over the existing proposals.     

依赖源汇聚点的组播协议

域间组播一直是大范围内部署组播时需要考虑的主要因素。依赖源汇聚点组播是一种基于Chord查找协议的简单有效的域间组播方案，方案中接收者的指定路由器（DR）使用Chord协议获得源RP地址，并加入源RP树。依赖源汇聚点的组播方案是一种域同ASM解决方案；能提供很好的容错性和可扩展性；支持主机移动组播，但不会造成三角路由问题。     

Dynamic Host-Group/Multi-Destination Routing for Multicast Sessions

Multicast routing research efforts have mostly focused on supporting the host-group model in which multicast packets are addressed to a host (or multicast) group. Another multicast routing approach uses multi-destination addressing, where a multicast packet carries a list of the unique (unicast) addresses of all the group members. This form of routing can be accomplished using limited or no additional state beyond the existing unicast routing tables. It, therefore, scales well with the number of multicast sessions but does not scale well with the size of the multicast group and, in fact, requires the size of the multicast group to be below a certain threshold. In this paper, we envision a future scenario in which both host-group and multi-destination addressing routing approaches coexist within the Internet. We develop a dynamic routing context for this future scenario wherein a multicast session can adapt among different routing configurations depending on the number of multicast group members and how this number changes over time. We consider three routing options: (1) A single multi-destination addressed flow – suitable for small-group sessions, (2) multiple multi-destination addressed flows – suitable for medium-group sessions and (3) a single host-group addressed flow – suitable for large-group sessions. For multicast sessions that vary in group membership over time, different routing protocols may be best at different points in time. Our work is concerned with the development and evaluation of protocols that allow a multicast session to dynamically switch among these three routing options as the size of the session changes.     

Source Filtering in IP Multicast Routing

IP multicasting is an efficient group communication mechanism. It avoids transmitting packets from a sender to each of the receivers separately. Under the current IP multicast model, once having joined a group, the host will receive all data destined to the group from any source, irrespective of whether it wishes to receive them. This paper studies source filtering (SF) in IP multicasting. Source filtering allows individual hosts to specify the reception of packets sent to a multicast group only from a list of source addresses or to explicitly identify a list of the sources whose data the hosts do not want to receive. We investigate the issue of source filtering in the context of multicast routing protocols, and provide support of source filtering for shared-tree based IP multicast routing. We also discuss how source filtering improves the performance of existing work on IP multicast. Finally, we provide analysis and conduct simulations to evaluate the performance of the proposed SF mechanism. The results show that our mechanism allows better bandwidth utilization and scalability than those without the capability of source filtering, thus achieving a truly efficient use of resources for IP multicasting     

Scalable QoS-based IP multicast over label-switching wireless ATMnetworks

A Mobile IP multicast prototype that integrates a label-switching wireless asynchronous transfer mode, the mobile core-based multicast architecture, and an Internet multicast infrastructure is presented. MCOM creates multiple core-based layer 2 multicast trees that are independently established in member networks. They are interconnected via the Internet using layer 3 multicast routing. Gateways on the border of the Internet and wireless ATM networks convert ATM multicast traffic to suitable IP packets as well as converting from IP packets to ATM cells for MCOM. To solve the cell interleaving problem that results, ATM block transfer/immediate transmission capability is reasonably modified. Additionally, class-based block buffer management for ATM multicast connections is built into wireless ATM switches for soft quality of service control. Dynamic group management, multicast channel rerouting, and reliable multicasting are also studied in relation to existing Internet protocols like Mobile IP, Internet group management protocols, and multicast routing protocols     

MPLS security: an approach for unicast and multicast environments

Multi-Protocol Label Switching (MPLS) network architecture does not protect the confidentiality of data transmitted. This paper proposes a mechanism to enhance the security in MPLS networks by using multi-path routing combined with a modified (k, n) threshold secret sharing scheme. An Internet Protocol (IP) packet entering MPLS ingress router can be partitioned into n shadow (share) packets, which are then assigned to maximally node disjoint paths across the MPLS network. The egress router at the end will be able to reconstruct the original IP packet if it receives any k share packets. The attacker must therefore tap at least k paths to be able to reconstruct the original IP packet that is being transmitted, while receiving k???1 or less of share packets makes it hard or even impossible to reconstruct the original IP packet. In this paper, we consider the multicast case in addition to the unicast. To our best knowledge, no work has been published for MPLS multicast security. We have implemented our model and measured its time complexity on variable packets size.     

High-throughput multicast routing metrics in wireless mesh networks

The stationary nature of nodes in a mesh network has shifted the main design goal of routing protocols from maintaining connectivity between source and destination nodes to finding high-throughput paths between them. Numerous link-quality-based routing metrics have been proposed for choosing high-throughput routing paths in recent years. In this paper, we study routing metrics for high-throughput tree or mesh construction in multicast protocols. We show that there is a fundamental difference between unicast and multicast routing in how data packets are transmitted at the link layer, and accordingly how the routing metrics for unicast routing should be adapted for high-throughput multicast routing. We propose a low-overhead adaptive online algorithm to incorporate link-quality metrics to a representative multicast routing protocol. We then study the performance improvement achieved by using different link-quality-based routing metrics via extensive simulation and experiments on a mesh-network testbed, using ODMRP as a representative multicast protocol.Our extensive simulation studies show that: (1) ODMRP equipped with any of the link-quality-based routing metrics can achieve higher throughput than the original ODMRP. In particular, under a tree topology, on average, ODMRP enhanced with link-quality routing metrics achieve up to 34% higher throughput than the original ODMRP under low multicast sending rate; (2) the improvement reduces to 21% under high multicast sending rate due to higher interference experienced by the data packets from the probe packets; (3) heavily penalizing lossy links is an effective way in the link-quality metric design to avoid low-throughput paths; and (4) the path redundancy from a mesh data dissemination topology in mesh-based multicast protocols provides another degree of robustness to link characteristics and reduces the additional throughput gain achieved by using link-quality-based routing metrics. Finally, our experiments on an eight-node testbed show that on average, ODMRP using SPP and PP achieves 14% and 17% higher throughput over ODMRP, respectively, validating the simulation results.     

Multicast support for mobile hosts using Mobile IP: Design issues and proposed architecture

In this paper, we consider the problem of providing multicast to mobile hosts using Mobile IP for network routing support. Providing multicast in an internetwork with mobile hosts is made difficult because many multicast protocols are inefficient when faced with frequent membership or location changes. This basic difficulty can be handled in a number of ways, but three main problems emerge with most solutions. The tunnel convergence problem, the duplication problem, and the scoping problem are identified in this paper and a set of solutions are proposed. The paper describes an architecture to support IP multicast for mobile hosts using Mobile IP. The basic unicast routing capability of Mobile IP is used to serve as the foundation for the design of a multicast service facility for mobile hosts. We believe that our scheme is transparent to higher layers, simple, flexible, robust, scalable, and, to the extent possible, independent of the underlying multicast routing facility. For example, our scheme could interoperate with DVMRP, MOSPF, CBT, or PIM in the current Internet. Where differences exist between the current version of IP (IPv4) and the next generation protocol (IPv6), these differences and any further optimizations are discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

The PIM architecture for wide-area multicast routing

The purpose of multicast routing is to reduce the communication costs for applications that send the same data to multiple recipients. Existing multicast routing mechanisms were intended for use within regions where a group is widely represented or bandwidth is universally plentiful. When group members, and senders to those group members, are distributed sparsely across a wide area, these schemes are not efficient; data packets or membership report information are occasionally sent over many links that do not lead to receivers or senders, respectively. We have developed a multicast routing architecture that efficiently establishes distribution trees across wide area internets, where many groups will be sparsely represented. Efficiency is measured in terms of the router state, control message processing, and data packet processing, required across the entire network in order to deliver data packets to the members of the group. Our protocol independent multicast (PIM) architecture: (a) maintains the traditional IP multicast service model of receiver-initiated membership, (b) supports both shared and source-specific (shortest-path) distribution trees, (c) is not dependent on a specific unicast routing protocol, and (d) uses soft-state mechanisms to adapt to underlying network conditions and group dynamics. The robustness, flexibility, and scaling properties of this architecture make it well-suited to large heterogeneous internetworks     

Optimal Time Slot Assignment Algorithm for Combined Unicast and Multicast Packets

This paper considers a packet‐scheduling algorithm for a given combined traffic of unicast and multicast data packets and proposes a hybrid router with several dedicated buses for multicast traffic. Our objective is to develop a scheduling algorithm that minimizes schedule length for the given traffic in the hybrid router. We derive a lower bound and develop an optimal solution algorithm for the hybrid router.     

Optimized multipath network coding in lossy wireless networks

Network coding has been a prominent approach to a series of problems that used to be considered intractable with traditional transmission paradigms. Recent work on network coding includes a substantial number of optimization based protocols, but mostly for wireline multicast networks. In this paper, we consider maximizing the benefits of network coding for unicast sessions in lossy wireless environments. We propose Optimized Multipath Network Coding (OMNC), a rate control protocol that dramatically improves the throughput of lossy wireless networks. OMNC employs multiple paths to push coded packets to the destination, and uses the broadcast MAC to deliver packets between neighboring nodes. The coding and broadcast rate is allocated to transmitters by a distributed optimization algorithm that maximizes the advantage of network coding while avoiding congestion. With extensive experiments on an emulation testbed, we find that OMNC achieves more than two-fold throughput increase on average compared to traditional best path routing, and significant improvement over existing multipath routing protocols with network coding. The performance improvement is notable not only for one unicast session, but also when multiple concurrent unicast sessions coexist in the network.     

Incremental service deployment using the hop-by-hop multicast routing protocol

IP multicast is facing a slow take-off although it has been a hotly debated topic for more than a decade. Many reasons are responsible for this status. Hence, the Internet is likely to be organized with both unicast and multicast enabled networks. Thus, it is of utmost importance to design protocols that allow the progressive deployment of the multicast service by supporting unicast clouds. This paper presents HBH (hop-by-hop multicast routing protocol). HBH adopts the source-specific channel abstraction to simplify address allocation and implements data distribution using recursive unicast trees, which allow the transparent support of unicast-only routers. An important original feature of HBH is its tree construction algorithm that takes into account the unicast routing asymmetries. Since most multicast routing protocols rely on the unicast infrastructure, the unicast asymmetries impact the structure of the multicast trees. We show through simulation that HBH outperforms other multicast routing protocols in terms of the delay experienced by the receivers and the bandwidth consumption of the multicast trees. Additionally, we show that HBH can be incrementally deployed and that with a small fraction of HBH-enabled routers in the network HBH outperforms application-layer multicast.     

A Domain-Based Routing Protocol for SSM Source Mobility in Mobile IPv6 Networks

In Mobile IP, the signaling traffic overhead will be too high since the new Care-of-Address (CoA) of the mobile node (MN) is registered all the way with the home agent (HA) whenever the MN has moved into a new foreign network. To complement Mobile IP in better handling local movement, several IP micro protocols have been proposed. These protocols introduce a hierarchical mobility management scheme, which divides the mobility into micro mobility and macro mobility according to whether the host's movement is intra-domain or inter-domain. Thus, the requirements on performance and flexibility are achieved, especially for frequently moving hosts. This paper introduces a routing protocol for multicast source mobility on the basis of the hierarchical mobile management scheme, which provides a unified global architecture for both uni- and multicast routing in mobile networks. The implementation of multicast services adopts an improved SSM (Source Specific Multicast) model, which combines the advantages of the existing protocols in scalability and mobility transparency. Simulation results show that the proposed protocol has better performance than the existing routing protocols for SSM source mobility.     

Intelligent Internal Stealthy Attack and its Countermeasure for Multicast Routing Protocol in MANET

Multicast communication of mobile ad hoc networks is vulnerable to internal attacks due to its routing structure and high scalability of its participants. Though existing intrusion detection systems (IDSs) act smartly to defend against attack strategies, adversaries also accordingly update their attacking plans intelligently so as to intervene in successful defending schemes. In our work, we present a novel indirect internal stealthy attack on a tree‐based multicast routing protocol. Such an indirect stealthy attack intelligently makes neighbor nodes drop their routing‐layer unicast control packets instead of processing or forwarding them. The adversary targets the collision avoidance mechanism of the Medium Access Control (MAC) protocol to indirectly affect the routing layer process. Simulation results show the success of this attacking strategy over the existing “stealthy attack in wireless ad hoc networks: detection and countermeasure (SADEC)” detection system. We design a cross‐layer automata‐based stealthy attack on multicast routing protocols (SAMRP) attacker detection system to identify and isolate the proposed attacker. NS‐2 simulation and analytical results show the efficient performance, against an indirect internal stealthy attack, of SAMRP over the existing SADEC and BLM attacker detection systems.     

Forwarding state scalability for multicast provisioning in IP networks

Forwarding state scalability is one of the critical issues that delay the multicast deployment in IP networks. With traditional multicast routing protocols, a forwarding tree is built for each multicast session, and each router is required to maintain a forwarding entry for each multicast session whose distribution tree passes through the router. This poses the multicast forwarding state scalability issue when the number of concurrent multicast sessions is very large. We first present a survey of existing work addressing this scalability issue for providing scalable IP multicast. Then we extend an existing multicast routing protocol, Multicast Extension to OSPF (MOSPF), to scale well with respect to the number of concurrent multicast sessions by introducing tunnel support. This extension aims to reduce the protocol overhead associated with MOSPF. Simulation results show that the extension can significantly reduce multicast forwarding state and computational overhead at routers without affecting the per-destination shortest path characteristic of a resulting tree or introducing extra control overhead.     

Explicit Multicasting for Mobile Ad Hoc Networks

In this paper we propose an explicit multicast routing protocol for mobile ad hoc networks (MANETs). Explicit multicasting differs from common approaches by listing destination addresses in data packet headers. Using the explicit destination information, the multicast routing protocol can avoid the overhead of employing its own route construction and maintenance mechanisms by taking advantage of unicast routing table. Our protocol – termed Differential Destination Multicast (DDM) – is an explicit multicast routing protocol specifically designed for MANET environment. Unlike other MANET multicasting protocols, instead of distributing membership control throughout the network, DDM concentrates this authority at the data sources (i.e. senders) thereby giving sources knowledge of group membership. In addition, differentially-encoded, variable-length destination headers are inserted in data packets which are used in combination with unicast routing tables to forward multicast packets towards multicast receivers. Instead of requiring that multicast forwarding state to be stored in all participating nodes, this approach also provides the option of stateless multicasting. Each node independently has the choice of caching forwarding state or having its upstream neighbor to insert this state into self-routed data packets, or some combination thereof. The protocol is best suited for use with small multicast groups operating in dynamic MANET environment.     

Wormhole IP over (connectionless) ATM

High-speed switches and routers internally operate using fixed-size cells or segments; variable-size packets are segmented and later reassembled. Connectionless ATM was proposed to quickly carry IP packets segmented into cells (AAL5) using a number of hardware-managed ATM VCs. We show that this is analogous to wormhole routing. We modify this architecture to make it applicable to existing ATM equipment: we propose a low-cost, single-input, single-output wormhole IP router that functions as a VP/VC translation filter between ATM subnetworks. When compared to IP routers, the proposed architecture features simpler hardware and lower latency. When compared to software-based IP-over-ATM techniques, the new architecture avoids the overheads of a large number of labels, or the delays of establishing new flows in software after the first few packets have suffered considerable latencies. We simulated a wormhole IP routing filter, showing that a few tens of hardware-managed VCs per outgoing VP usually suffice. We built and successfully tested a prototype, operating at 2×155 Mb/s, using one field programmable gate array (FPGA) and DRAM. Simple analysis shows that operation at 10 Gb/s and beyond is feasible today     

IP多播技术

主要叙述了ＩＰ多播技术的基本概念、多播协议以及正在发展的新协议，并简要描述了多播主干（Ｍｂｏｎｅ）和多播的前景。     

The Performance Analysis of the Multicast Extension Support for Proxy MIPv6

Mobile multicast is based on the traditional multicast protocols and the mobility support protocols to provide the multicast services for the mobile subscribers. Several mobile multicast methods were proposed in the past few years, but most of them are based on Mobile IPv6 and its variants which require the mobile node to support the mobility function. Recently, Proxy Mobile IPv6 (PMIPv6) was proposed to provide the mobility support for the mobile node with or without mobility function, and the previous studies have shown that PMIPv6 can improve the performance in term of the handover performance and protocol cost. However, PMIPv6 mainly concerns on the mobility support for unicast routing and little considers the multicast routing. In this paper, we propose two multicast methods called the MAG (Mobile Access Gateway)-based method and LMA (Local Mobility Anchor)-based method based on the different multicast delivery transmission path to extend PMIPv6, and analyze their performance under the different scenarios. The analytical results show that the LMA-based method is suitable for the higher speed, bigger domain size, and larger network topology scenarios, whereas the MAG-based method is suitable for the lower speed, smaller domain size and smaller network topology scenarios.