支持Internet实时多媒体应用的Overlay技术研究  

Study on Overlay Mechanisms of Supporting Real-Time Multimedia Applications in Internet

作　　者：吴云波[1] 李志蜀[1] 吴云海 陈志华[3] 殷锋[1] 卢暾[1] 元昌安[1] 

机构地区：[1]四川大学计算机学院 [2]云南省水电勘测设计院,昆明650028 [3]云南省昆明市气象局,昆明650028

出　　处：《计算机科学》2006年第4期118-121,129,共5页Computer Science

基　　金：863课题资助项目课题号2002AA144020

摘　　要：目前出现的大规模(large-scale)的多媒体应用对 Internet 提出了新的挑战。传统的 IP 组播(IP multicast,IPM)由于实现技术的复杂性,很难在 Internet 上推广。相反,基于叠加网络(overlay network,ON)的解决方案则受到各方面的关注。本文针对大规模实时多媒体应用需求,通过建立评价参数模型对 ON 协议进行研究。尤其对 overlay组播(overiay multicast,OM)的 QoS 控制、可靠性以及可伸缩性机制进行了分析。与 IPM 相比,OM 虽然有性能代价(performance penalty)问题,但是 OM 能方便、灵活地利用多种高层的功能实现,基于 hop-by-hop 方式有效地提供E2E(end-to-end)的可靠性和 Qos 保障,并且较好地支持 TCP-friendliness,具有良好的可伸缩性。此外,OM 的基础网络(infrastructure/underlay network)无关性,也使其容易在 Internet 中进行配置。以上特性使得 OM 成为支持 Inter-net 上大规模实时多媒体应用的最具前景的技术。Recently, large-scale multimedia applications put a challenge on traditional Internet. Due to many drawbacks in implementing reliability and QoS control, as well as requirements in upgrating infrastructure components, IP multicast has more difficulties to be widely deployed in Internet. However, circumventting these problems via overlay networking increasingly attracts many interesting of researchers. This paper models some measures of relaibility, QoS and scalability relating to large-scale real time multimedia applications. Furthermore, overlay networking protocols especially overlay multicast protocols have been analyzed referring to these issues. Comparing to IP multicast, overlay mul- ticast may induce some delay penalty, but this shortcoming is insignificant by virtues of proper protocol design. Overlay multicast can employ upper-layer functionalities in where, thus make it feasibly and efficiently to achieve E2E reliability and QoS based on hop-by-hop. Besides, scalability as well as TCP-frienliness is guaranteed efficiently in overlay multicast. Moreover, no infrastructure support is needed, thus paving the way for widely deployment in Internet. Advantages above have made overlay multicast to be a promising techniques for large-scale real time multimedia applications in Interact.

关 键 词：OVERLAY INTERNET 实时多媒体应用 QOS 可靠性控制 可伸缩性 

分 类 号：TP393.4[自动化与计算机技术—计算机应用技术] TP37[自动化与计算机技术—计算机科学与技术]