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.     

Fast adaptive routing supporting mobile senders in Source Specific Multicast

IP multicast deployment recently progresses, but group services often remain restricted to limited domains and fail to comply with route-optimizing mobility management of the next generation Internet. Source Specific Multicast (SSM) facilitates transparent inter-domain routing and is expected to globally disseminate to many users and services. However, mobility support for Source Specific Multicast is still known to be a major open problem. In this paper, we propose the Enhanced Tree Morphing (ETM) protocol for extending SSM routing to mobile multicast sources. The scheme dynamically adapts SSM forwarding states to sender mobility, and transforms (morphs) source specific distribution trees into new, optimal trees rooted at a relocated source. ETM is simple, robust and secure, while it admits superior performance in packet forwarding at a low signaling overhead. Extensive evaluations based on a full protocol implementation, and simulations based on real-world topology data are performed, granting full insight into the properties of packet loss and delay stretch, protocol convergence times and router state evolution during single and rapidly repeated handovers. In a constant bit rate scenario, an ETM source handover typically leads to a slightly increasing delay of the first data packet, only. When operating on realistic network topologies, the protocol uniformly converges within less than 50 ms, thereby sustaining robustness under rapid source movement at all speeds common to our mobile world. Further optimizations are identified for FMIPv6 and for multihomed nodes.     

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.     

Investigation of multicast‐based mobility support in all‐IP cellular networks

To solve the IP mobility problem, the use of multicast has been proposed in a number of different approaches, applying multicast in different characteristic ways. We provide a systematic discussion of fundamental options for multicast‐based mobility support and the definition and experimental performance evaluation of selected schemes. The discussion is based on an analysis of the architectural, performance‐related, and functional requirements. By using these requirements and selecting options regarding network architecture and multicast protocols, we identify promising combinations and derive four case studies for multicast‐based mobility in IP‐based cellular networks. These case studies include both the standard any‐source IP multicast model as well as non‐standard multicast models, which optimally utilize the underlying multicast. We describe network architecture and protocols as well as a flexible software environment that allows to easily implement these and other classes of mobility‐supporting multicast protocols. Multicast schemes enable a high degree of flexibility for mobility mechanisms in order to meet the service quality required by the applications with minimal protocol overhead. We evaluate this overhead using our software environment by implementing prototypes and quantifying handoff‐specific metrics, namely, handoff and paging latency, packet loss and duplication rates, as well as TCP goodput. The measurement results show that these multicast‐based schemes improve handoff performance for high mobility in comparison to the reference cases: basic and hierarchical Mobile IP. Comparing the multicast‐schemes among each other the performance for the evaluated metrics is very similar. As a result of the conceptual framework classification and our performance evaluations, we justify specific protocol mechanisms that utilize specific features of the multicast. Based on this justification, we advocate the usage of a source‐specific multicast service model for multicast‐based mobility support that adverts the weaknesses of the classical Internet any‐source multicast service model. Copyright © 2006 John Wiley & Sons, Ltd.     

Morphing distribution trees—On the evolution of multicast states under mobility and an adaptive routing scheme for mobile SSM sources

Source Specific Multicast (SSM) promises a wider dissemination of group distribution services than Any Source Multicast, as it relies on simpler routing strategies with reduced demands on the infrastructure. However, SSM is designed for á priori known and changeless addresses of multicast sources and thus withstands any easy extension to mobility. Up until now only few approaches arose from the Internet research community, leaving SSM source mobility as a major open problem. The purpose of this paper is twofold. At first we analyze characteristic properties of multicast shortest path trees evolving under source mobility. Analytically and by stochastic simulations we derive measures on the complexity of SSM routing under source mobility. At second we introduce a straightforward extension to multicast routing for transforming (morphing) source specific delivery trees into optimal trees rooted at a relocated source. All packet forwarding is done free of tunneling. Multicast service disruption and signaling overhead for the algorithms remain close to minimal. Further on we evaluate the proposed scheme using both, analytical estimates and stochastic simulations based on a variety of real-world Internet topology data. Detailed comparisons are drawn to bi-directional tunneling, as well as to proposals on concurrent distribution trees.     

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.     

IP multicasting over ATM networks

The Internet protocol (IP) multicast model involves a combination of intrasubnet and intersubnet multicast mechanisms. Technologies supporting a given subnet are expected to have native mechanisms for supporting intrasubnet forwarding of packets sent to multicast destinations. Multicast routers attach to subnets and provide intersubnet forwarding of multicast packets, using interdomain multicast routing protocols developed by the Internet Engineering Task Force (IETF). Unfortunately, ATM networks based on UNI 3.0 or UNI 3.1 signaling service do not provide the native multicast support expected by IP. This has led the IETF to develop the “MARS model”-a fairly complex mechanism for emulating intrasubnet multicast support required when running IPs over ATMs. This paper takes a high level look at the IP multicast service, examines the limitations of the ATM point-to-multipoint virtual channel service, and describes the major architectural points of the MARS model     

不可靠信道上抗主动攻击的组播认证

组播是视频会议、协同工作等各种群组应用的基本通讯模式,组播安全性的研究具有重要意义.组播通常构建在不可靠的通讯协议上,因此存在数据包的丢包现象.大多数的组播认证方案不能用于这种环境,其他一些方案的主要目标是针对网络通讯故障引起的随机包丢失情况,而不能抵抗主动攻击.本文提出了抗部分碰撞哈希函数簇的思想,然后利用哈希图和纠错码技术提构造一种在不可靠信道上新的组播认证方案.该方案不仅具有很高的通讯性能和计算性能,并且在存在部分数据包丢失的情况下也可以抵抗主动攻击.本文提出了一种针对该方案特性的不可靠信道组播认证的形式安全模型,并在此安全模型下基于规约技术证明了该方案的安全性.     

Multicast Routing in Mobile Ad Hoc Networks

We focus on one critical issue in mobile ad hoc networks that is multicast routing. Advantages and limitations of existing routing protocols are illustrated. Optimal routes, stable links, power conservation, loop freedom, and reduced channel overhead are the main features to be addressed in a more efficient mechanism. In this paper, we propose a new on-demand multicast routing protocol, named Source Routing-based Multicast Protocol (SRMP). Our proposition addresses two important issues in solving routing problems: (i) path availability concept, and (ii) higher battery life paths. SRMP applies a source routing mechanism, and constructs a mesh to connect group members. It provides stable paths based on links' availability according to future prediction of links' states, and higher battery life paths. This protocol succeeded to minimize network load via designing optimal routes that guarantee reliable transmission and active adaptability. A performance comparison study with On-demand Multicast Routing Protocol (ODMRP) and Adaptive Demand-driven Multicast Routing (ADMR) protocol is undertaken. Analysis results show the strength of the SRMP nodes' selection criteria and its efficient energy consumption compared to the other two protocols.     

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.     

Group Communication Using Modular Protocol Stacks

Today's distributed systems consist of many different components, making the efficient management of such systems an extremely difficult task. Group communication should provide a potential solution to make the management process more flexible. It is possible to build a group communication system based on traditional distributed technology such as CORBA (Common Object Request Broker Architecture), but efficiency is poor due to lack of support for multicast and the overhead of building groups in current commercially available products. Multicast is a key part of a future group communication architecture and although reliability is not yet supported there are workarounds which provide a solution. This paper discusses the design and implementation of reliable IP multicast protocols for group communication. One important aspect of this work is the modularisation of the protocol blocks, and the design of a modular protocol, which can be used in conjunction with other similar protocol blocks to build a communication stack for group communications, is described in detail.     

Overlay,Borůvka‐based,Ad‐hoc multicast Protocol: description and performance analysis

This paper presents a novel Mobile Ad‐hoc NETworks (MANET) multicast protocol, named Overlay Borůvka‐based Ad‐hoc Multicast Protocol (OBAMP), and evaluates its performance. OBAMP is an overlay protocol: it runs only in the end‐systems belonging to the multicast group. OBAMP has three distinctive features, which give to the protocol a good performance in terms of distribution efficiency: (i) its distribution tree closely resembles the minimum spanning tree; (ii) it exploits broadcast communications; (iii) its design limits not only overlay signaling but also network‐layer signaling. In addition, OBAMP can cope with node failures in a very short time. As a consequence, OBAMP has a low latency and a high delivery ratio, even when the group size increases. To prove these statements, we analyze the performance of OBAMP with ns‐2 and compare it with three state‐of‐the‐art protocols, namely ODMRP (a network‐layer protocol), ALMA, and AMRoute (two overlay protocols). The overlay protocols are assumed to use AODV as underlying routing protocol. Also, we stress that we have implemented OBAMP, in Java, and we have tested it on the field, to prove its feasibility; to allow fellow researchers to reproduce and test our work we published all simulation and implementation codes. Copyright © 2007 John Wiley & Sons, Ltd.     

Domain Constrained Multicast: A New Approach for IP Multicast Routing

One of major reasons why IP multicast has not been well deployed is the complexity of IP multicast routing. Since existing IP multicast routing protocols have been designed independently of IP unicast routing protocols, a router must maintain routing tables for both IP mutlicast and unicast routing. This is, in particular, a big burden for an inter-domain router. In addition, by using existing IP multicast routing protocols, we cannot realize an application that a sending host outside the designated domain sends IP multicast packets only towards the designated domain. To resolve above issues, we propose a new architecture for IP multicast, which is called Domain Constrained Multicast (DCM). In this architecture, IP multicast packets are forwarded to a border router of the designated domain using IP unicast routing. And then, IP multicast packets are delivered inside the designated domain using IP multicast. We propose an address format when realizing the DCM architecture using IPv6. We describe the extension of the DCM architecture for applying it to inter-domain IP multicast routing. Finally, we have compared the DCM architecture for inter-domain routing, with existing inter-domain IP multicast routing protocols such as MSDP and BGMP.     

An efficient mesh‐based multicast routing protocol in mobile ad hoc networks

Mesh‐based multicast routing protocols for mobile ad hoc networks (MANETs) build multiple paths from senders to receivers to deliver packets even in the presence of links breaking. This redundancy results in high reliability/robustness but may significantly increase packet overhead. This paper proposes a mesh‐based multicast protocol, called centered protocol for unified multicasting through announcements (CPUMA), that achieves comparable reliability as existing mesh‐based multicast protocols, however, with significantly much less data overhead. In CPUMA, a distributed core‐selection and maintenance algorithm is used to find the source‐centric center of a shared mesh. We leverage data packets to center the core of each multicast group shared mesh instead of using GPS or any pre‐assignment of cores to groups (the case of existing protocols). The proposed centering scheme allows reducing data packet overhead and creating forwarding paths toward the nearest mesh member instead of the core to reduce latency. We show, via simulations, that CPUMA outperforms existing multicast protocols in terms of data packet overhead, and latency while maintaining a constant or better packet delivery ratio, at the cost of a small increase in control overhead in a few scenarios. Copyright © 2010 John Wiley & Sons, Ltd.     

New Approach to Inter‐domain Multicast Protocols

IPTV broadcast channels and video content distribution are increasingly saturating network paths. New solutions based on inter‐domain multicast protocols could contribute to the enhancement of multimedia content distribution over the Internet. The aim of this paper is to propose new capabilities for an existing inter‐domain multicast protocol, the Protocol Independent Multicast‐Sparse Mode. We describe the modified protocol and analyze its behavior using newly developed tools based on an open‐source software simulator. The resulting protocol does not require topology information, which is advantageous for easier deployment. In addition, the adopted solution avoids inherent problems with inter‐domain multicast routing, such as multiple paths and path asymmetries.     

Light-weight multicast services (LMS): a router-assisted scheme for reliable multicast

Building on the success of unicast IP, IP Multicast adopted a simple, open, best-effort delivery model with many-to-many semantics. Despite several years of effort, a general, scalable and reliable end-to-end transport protocol analogous to TCP has proven elusive. Proposed solutions are either inflexible, or incur high control overhead. We present Lightweight Multicast Services (LMS), which enhance the IP Multicast model with simple forwarding services to facilitate scalable and efficient (compared to pure end-to-end) solutions to problems such as reliable multicast. In LMS, routers tag and steer control packets to preselected endpoints and perform fine-grain multicast to guide responses to a subset of the group without transport-level processing. LMS divides error control into transport and forwarding components, which allows the former to remain at the end-points while the latter is pushed to the routers, where it can be implemented very efficiently. The division is clean, resulting in significant gains in performance and scalability, while reducing application complexity. LMS reaches beyond reliable multicast to applications such as scalable collect, any-cast, and in general, any application that can benefit from a hierarchy congruent with the underlying topology.     

AMRoute: Ad Hoc Multicast Routing Protocol

The Ad hoc Multicast Routing protocol (AMRoute) presents a novel approach for robust IP Multicast in mobile ad hoc networks by exploiting user-multicast trees and dynamic logical cores. It creates a bidirectional, shared tree for data distribution using only group senders and receivers as tree nodes. Unicast tunnels are used as tree links to connect neighbors on the user-multicast tree. Thus, AMRoute does not need to be supported by network nodes that are not interested/capable of multicast, and group state cost is incurred only by group senders and receivers. Also, the use of tunnels as tree links implies that tree structure does not need to change even in case of a dynamic network topology, which reduces the signaling traffic and packet loss. Thus AMRoute does not need to track network dynamics; the underlying unicast protocol is solely responsible for this function. AMRoute does not require a specific unicast routing protocol; therefore, it can operate seamlessly over separate domains with different unicast protocols. Certain tree nodes are designated by AMRoute as logical cores, and are responsible for initiating and managing the signaling component of AMRoute, such as detection of group members and tree setup. Logical cores differ significantly from those in CBT and PIM-SM, since they are not a central point for data distribution and can migrate dynamically among member nodes. Simulation results (using ns-2) demonstrate that AMRoute signaling traffic remains at relatively low level for typical group sizes. The results also indicate that group members receive a high proportion of data multicast by senders, even in the case of a highly dynamic network.     

IP 多播路由协议的分析

分析介绍了几种典型的IP多播路由协议，如DVMRP、PIM、MOSPF和CBT等，并对这几种IP多播路由协议进行了分析对比。     

Multicast-Kommunikation im Internet

The Internet supports group communications by its multicast concept. Several Internet protocol extensions and new protocols have been developed in order to realize multicast in the Internet. This paper focuses on the IP multicast architecture, in particular on the IP multicast extensions and the corresponding multicast routing protocols. The IP multicast model has significant impacts on the underlying network technologies and on the transport protocols and applications on top of IP. These impacts are also discussed in the paper.     

关于IP多播路由协议的研究与分析

介绍分析了几种典型的IP多播路由协议，如距离向量多播路由协议、协议独立多播、多播开放最短路径优先和基于核心树的多播等，并对这几种IP多播路由协议进行了分析对比。