Challenges and opportunities of delivering IP-based residential television services

This article describes the main challenges of implementing an end-to-end architecture for delivery of high-quality, IP-based residential TV services to residential customers. The IP-based approach can be implemented with an IP multicast overlay network with traditional routers or use IP-multicast-aware ATM switching systems. Both approaches use IP multicast to transport MPEG-2 broadcast video and can work on any access architecture, especially on copper-based architectures (xDSL) such as ASDL and VDSL. The main challenges met while implementing the IP-based architecture are competitive positioning relative to traditional CATV architectures, overall architecture, head-end architecture and quality issues, traffic engineering for stringent QoS requirements, IP multicast requirements, and business case considerations. The IP-based approach described leverages Internet technology advancements and capitalizes on the impacts of Internet on interactive entertainment. Video channel manipulation at the head-end is dependent on access bandwidth and affects video quality. Video traffic management to meet stringent QoS requirements is challenging at the IP layer. High-capacity, responsive IP multicasting is essential to achieving high service quality. Cost-effective IP multicasting is a critical component of the business case.     

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.     

Internet Multicasting of IPTV With Essentially-Zero Delay Jitter

A technology for multicasting packetized multimedia streams such as IPTV over the Internet backbone is proposed and explored through extensive simulations. An RSVP or DiffServ algorithm is used to reserve resources (i.e., bandwidth and buffer space) in each packet-switched IP router in an IP multicast tree. Each IP router uses an Input-Queued (IQ) switch architecture with unity speedup. A recently proposed low-jitter scheduling algorithm is used to pre-compute a deterministic transmission schedule for each IP router. The IPTV traffic will be delivered through the multicast tree in a deterministic manner, with bounds on the maximum delay and jitter of each packet (or cell). A playback buffer is used at each destination to filter out residual network jitter and deliver a very low-jitter video stream to each end-user. Detailed simulations of an IPTV distribution network, multicasting 75 high-definition video streams over a fully-saturated IP backbone are presented. The simulations represent the transmission of 129 billion cells of real video data and where performed on a 160-node cluster computing system. In the steady-state, each IP router buffers approx. 2 cells (128 bytes) of video data per multicast output-port. The observed delay jitter is zero when a playback buffer of 15 milliseconds is used. All simulation parameters are presented.      

Mobile and Multicast IP Services in PACS: System Architecture, Prototype, and Performance

Traditionally, wireless cellular communication systems have been engineered for voice. With the explosive growth of Internet applications and users, there is an increasing demand on providing Internet services to mobile users based on the voice-oriented cellular networks. However, Internet services add a set of radically different requirements on to the cellular wireless networks, because the nature of communication is very different from voice. It is a challenge to develop an adequate network architecture and necessary systems components to meet those requirements.This paper describes our experience on developing Internet services, in particular, mobile and multicast IP services, in PACS (Personal Access Communication Systems). Our major contributions are five-fold: (i) PACS system architecture that provides wireless Internet and Intranet access by augmenting the voice network with IP routers and backbone links to connect to the Internet; (ii) simplified design of RPCU (Radio Port Controller Unit) for easy service maintenance and migration to future IP standards such as IPv6; (iii) native PACS multicast to efficiently support dynamic IP multicast and MBone connectivity; (iv) optimization and incorporation of Mobile IP into PACS handoff mechanism to efficiently support roaming within a PACS network as well as global mobility between PACS networks and the Internet; (v) successful prototype design of the new architecture and services verified by extensive performance measurements of IP applications. Our design experience and measurement results demonstrate that it is highly feasible to seamlessly integrate the PACS networks into the Internet with global IP mobility and IP multicast services.     

基于Agent实现组播在广域网中的传输

针对目前Internet中大部分路由器不支持组播数据传输的问题，本文基于Agent技术提出了一种实现广域网内组播数据传输的方法。该方法使用了基于Agent的通信模型．组播会话中的每个成员通过其上运行的Agent实现数据收发；并将能够实施IP组播通信的网络范围看作是一个组播域，在每个组播域中自动选择一个Agent作为主Agent(MA)，组播域中的其他Agent为备份Agent(BA)；在组播域内利用IP组播进行数据传输，在组播域间利用主Agent之间的TCP连接进行数据传输．从而使得组播通信能够跨越路由器的障碑。此外还实现了BA向MA的自动升级．保证了组播会话的可靠性和连续性。     

Mobility of sources and listeners: real-time support of multicast services

In today??s Internet there is an increasing demand for group-based multimedia sessions, such as video/audio conferencing, IPTV, push media. Moreover, there is an increasing trend for mobile communications, with large network dynamic events, which require fast resilience to keep, as much as possible, sessions alive over time. In this sense, the bandwidth-constrained data transport scheme of IP multicast allows traffic optimization throughout the network. However, current IP multicast support over mobile communications is not efficient, mainly due to the IP addressing scheme and mobility. If multicast sources mobility is taken into account, then the performance of IP multicast is significantly degraded, due to the requirement for constantly changing the overall multicast tree. In this paper we propose a new solution for agent-based multicast in both sources and listeners mobile environments, called MUlticast TEleport (MUTE). MUTE considers the existence of anchor points in the network that provide proxy features, assuming the view of multicast data source inside the network, and establishing independence between listeners and sources movements. Moreover, we propose MUTE extension to efficiently support time-sensitive sessions, which consists in integrating IEEE 802.21 and QoS-aware abstracted transport approach, to allow media independent transport with fast resilience support. The evaluation of MUTE was carried out in NS-2, and the results show that it is able to provide both multicast sources and listeners mobility with decreased disruption time and increased network performance in heterogeneous systems.     

Managing IP services over a PACS Packet Network

We have developed a system and network architecture to provide IP services in the Personal Access Communications System (PACS). IP datagrams are delivered to PACS users through the PACS packet-mode data service, achieving more efficient usage of wireless resources and supporting multimedia applications such as MBone audio and video. The architecture presented in this article augments the PACS voice network with IP routers and backbone links, called the PACS Packet Network (PPN), and is connected to the global Internet via gateways. Compared to the cellular digital packet data (CDPD) network, which employs its own network-layer mobility protocol and thus supports roaming within the CDPD network only, we have incorporated Mobile IP into the PACS handoff mechanism to further achieve global IP mobility. We have also developed native PACS multicast and a group management scheme to efficiently handle dynamic IP multicast and MBone connectivity. These features seamlessly integrate PACS into the global Internet and provide standard-conforming IP services with global mobility     

A case for end system multicast

The conventional wisdom has been that Internet protocol (IP) is the natural protocol layer for implementing multicast related functionality. However, more than a decade after its initial proposal, IP multicast is still plagued with concerns pertaining to scalability, network management, deployment, and support for higher layer functionality such as error, flow, and congestion control. We explore an alternative architecture that we term end system multicast, where end systems implement all multicast related functionality including membership management and packet replication. This shifting of multicast support from routers to end systems has the potential to address most problems associated with IP multicast. However, the key concern is the performance penalty associated with such a model. In particular, end system multicast introduces duplicate packets on physical links and incurs larger end-to-end delays than IP multicast. We study these performance concerns in the context of the Narada protocol. In Narada, end systems self-organize into an overlay structure using a fully distributed protocol. Further, end systems attempt to optimize the efficiency of the overlay by adapting to network dynamics and by considering application level performance. We present details of Narada and evaluate it using both simulation and Internet experiments. Our results indicate that the performance penalties are low both from the application and the network perspectives. We believe the potential benefits of transferring multicast functionality from end systems to routers significantly outweigh the performance penalty incurred.     

User-aware object-based video transmission over the next generation Internet

In this paper, we present a new user-aware adaptive object-based video transmission approach to heterogeneous users over the next generation Internet. Firstly, we describe a new transport framework for complex multimedia applications over the next generation Internet, which provides differentiation functionality within one IP session as well as among different IP sessions. It includes application-aware intelligent resource control at the edge of the network, fast transcoding and signaling in the network. Secondly, we propose a new bitstream classification, prioritization and packetization scheme in which different types of data such as shape, motion and texture are reassembled, assigned to different priority classes, and packetized separately based on their priorities. Thirdly, we present a simple but effective mechanism of object-based dynamic rate control and adaptation by selectively dropping packets in conjunction with differentiated services (Diffserv) to minimize the end-to-end quality distortion. Finally, we perform the queuing analysis for our mechanism and explore how to extend our approach to the multicast case. Experimental results demonstrate effectiveness of our proposed approach.     

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.     

基于卫星网络的IP组播技术

IP组播技术是新兴的网络技术,依托卫星网络的组播业务更是下一代Internet为用户提供的主流服务。文章详细介绍IP组播技术,对其在卫星网络应用中存在的主要问题、解决方法及常用的卫星组播网络拓扑结构进行阐述和分析。     

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     

IP multicast operational network management: design, challenges, and experiences

Multicast is a natural enabler for carrying high-bandwidth multimedia broadcasts and seminars on IP networks. Despite the increased need for IP multicast, its commercial deployment has not been widespread. The lack of appropriate network management tools for IP multicast has proven to be a major barrier to its deployment. In this paper we survey the currently available multicast management tools and discuss why they are insufficient. We describe the requirements of an operational multicast management platform and present mmon, a multicast network management system we have built, aimed primarily for use by engineering and operations personnel. Mmon has been tried by over 200 sites and is currently used at HP to manage the multicast network. We discuss some of the challenges and our experiences with designing, implementing, and deploying the system.     

GPM: A generic and scalable P2P model that optimizes tree depth for multicast communications

Group communications (real‐time and non‐real‐time) refer to one‐to‐many or many‐to‐many communications. On the one hand, multicast is considered as an appropriate solution for supporting group communication‐oriented applications (we distinguish IP network multicast from application layer multicast). On the other hand, peer‐to‐peer model tends to be a good candidate for supporting today Internet applications (e.g. P2P IPTV, P2P VoIP, etc.). In this context, P2P has attracted significant interest in the recent years. This is mainly due to its properties that also make P2P well adapted to today social networks. In this paper, we propose GPM (Generic P2P Multicast): a novel generic and scalable approach, that optimizes multicast tree depth in P2P networks (structured and unstructured), and contributes to control the network overlay latency. For multicast tree construction, the approach we propose is based on a distributed algorithm using a specific data structures (adjacency and forwarding matrixes). GPM model inherits from P2P attributes such as scalability, flexibility and fault tolerance, while taking into consideration the respective characteristics of one‐to‐many and many‐to‐many type of applications. We also give a performance evaluation for validation and comparison purposes while considering some main existing application layer multicast protocols. Copyright © 2011 John Wiley & Sons, Ltd.     

IP多播技术综述

随着Internet的广泛使用,多媒体业务等在网络中的增加,IP多播技术成为学术界、网路设备制造商、服务供应商等关注的热点,对未来网络进一步发展有重要意义。介绍IP多播技术的发展,讨论IP多播技术以及其体系结构,叙述几种常见的IP多播路由协议以及新发展,并分析了其应用。     

A distributed architecture for multiplayer interactive applicationson the Internet

This article describes the design, implementation, and evaluation of MiMaze, a distributed multiplayer game on the Internet, and, more precisely, it describes the design of dedicated transmission control mechanisms. MiMaze is implemented on a completely distributed communication architecture based on the IP multicast protocol suite (RTP/UDP/IP). This is the first work to analyze a distributed interactive game on the multicast Internet. The major element of the MiMaze architecture is a distributed synchronization mechanism that guarantees the consistency of the game regardless of network delay. This article provides on evaluation of the MiMaze game on the MBone, and discusses approaches to monitor and evaluate this new type of application. The main contribution of this work is to show, based on on example, the feasibility of this new family of applications on a best-effort network. It is shown that real-time interactivity can be maintained, provided that some level of inconsistency can be tolerated by the application. This work also highlights the role of multicast as an enabling technology for a real-time Internet     

Multicast for small conferences: a scalable multicast mechanism on IPv6

Many new Internet applications require data transmission from a sender to multiple receivers. Unfortunately, the IP multicast technology used today suffers from scalability problems, especially when used fro small and sparse groups. Multicast for small conferences (MSC) is a novel approach aimed at providing more efficient support for audio conferences, for example. It makes use of an IPv6 routing header. The unicast addresses of a small receiver group are put into the extension header in order to be forwarded to all group members. The results indicate that MSC has the potential to replace IP multicast for many delay-sensitive small group applications, even with very limited support from the network infrastructure.     

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     

大型IP网络中组播部署方案研究

近年来随着互联网用户数量的高速增长,网络多媒体应用的普及带来了IP网络带宽的急剧消耗,组播技术以其独特的优越性受到运营商的关注.然而,目前组播技术的使用仍然局限在少数小型网络中,组播部署缺少系统化、整体化的解决方案.本文介绍了一些关键的组播技术,在此基础上针对大型IP网络中的组播部署方案进行探讨,提出组播端到端的解决方案,并通过实验证明了该部署方案的可行性.