基于抵消算法的PIM-SM设计与实现
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摘要
随着我国三网融合的加速实施,以IPTV为代表的多媒体业务得到了极大的发展,而多媒体业务具有高带宽消耗等特点,迫使人们不断发展和推广IP组播技术。组播路由是IP组播的核心问题,目前已经存在多种组播路由协议,在这些协议中,PIM-SM协议因具有用户显式加入、流量泛洪控制、组播不限于一个域内等特点,成为目前网络中应用最广泛的组播路由协议。
本文通过对PIM-SM协议的研究,提出了一种分布式实现方案,该方案将PIM-SM的协议控制功能与数据转发功能分离,在控制平面中通过软件实现协议控制功能,在数据平面中利用硬件方式实现数据转发功能。本方案面临的最大问题是如何保持控制平面与数据平面的路由一致性,为此本文提出了一种基于抵消算法的路由下刷方案,经过实际的测试表明,该方案能够有效的维持控制与转发的路由一致性,是一种高效可行的路由下刷方案。本文完成的主要工作有：
(?)研究了组播转发方式以及IP组播体系结构,分析了PIM-SM的运行原理和特点。
(?)根据Comware平台架构和PIM-SM的特点,提出了一种控制与转发分离的分布式实现方案,并对控制平面进行了详细的研究和设计。
(?)分析了PIM-SM的平面一致性问题,根据PIM-SM的分布式实现结构,提出了在Comware平台下利用消息机制解决该问题的方案。并针对路由器处理大规格PIM-SM表项变化时,无法及时下刷表项信息的问题,提出了采用抵消算法减少冗余下刷消息的路由下刷方案。
(?)提出了实际的测试方案,对本项目的SPT切换功能进行了测试,证明了本文所设计方案的可行性。最后分析了项目存在的问题,提出了改进意见和来工作方向。
With the increasing development of three networks convergence in our country, the multimedia service like IPTV has been getting greatly improved. Multimedia service has some particular characteristics like high bandwidth consumption which stimulates the development and popularity of IP multicast. The crucial technology of IP multicast is multicast routing which has varieties of multicast routing protocals. Among those protocals, PIM-SM has become most popular due to its advantages such as user taking initiative to join, pan flood control and multicast not limited to a domain.
Based on the study of PIM-SM, this paper introduces a distributing implementation scheme of PIM-SM. The idea of the scheme is that the control plane and the data plane of PIM-SM are separately implemented. The protocal control is implemented in the control plane and the data forwarding is implemented in the data plane. The biggest problem is how to assure coherence between control plane and data plane. It introduces a routing synchronization scheme through offsetting algorithm to solve the problem. After a practical testing, the scheme can guarantee the same routing information in control plane and data plane. In short, it is an efficient and feasible routing synchronization scheme. The contents contained are below:
(?) Forwarding characteristic and IP multicast architecture are analyzed. The principles and features of PIM-SM are analyzed.
(?) Based on the architecture of Comware system and the characteristics of PIM-SM, it introduces a distributing implementation scheme.
(?) It analyzes the problem of plane coherence. Based on the implementation structure, it introduces a inner communication mechanics of Comware to solve the problem. It introduces a routing synchronization scheme through offsetting algorithm to solve the problem.
(?) Practical testing plan is given. The scheme of PIM-SM proves to be feasible in term of performance. Finally, it analyzes the existing problems and advances the betterment opinion and future work area.
本文通过对PIM-SM协议的研究,提出了一种分布式实现方案,该方案将PIM-SM的协议控制功能与数据转发功能分离,在控制平面中通过软件实现协议控制功能,在数据平面中利用硬件方式实现数据转发功能。本方案面临的最大问题是如何保持控制平面与数据平面的路由一致性,为此本文提出了一种基于抵消算法的路由下刷方案,经过实际的测试表明,该方案能够有效的维持控制与转发的路由一致性,是一种高效可行的路由下刷方案。本文完成的主要工作有：
(?)研究了组播转发方式以及IP组播体系结构,分析了PIM-SM的运行原理和特点。
(?)根据Comware平台架构和PIM-SM的特点,提出了一种控制与转发分离的分布式实现方案,并对控制平面进行了详细的研究和设计。
(?)分析了PIM-SM的平面一致性问题,根据PIM-SM的分布式实现结构,提出了在Comware平台下利用消息机制解决该问题的方案。并针对路由器处理大规格PIM-SM表项变化时,无法及时下刷表项信息的问题,提出了采用抵消算法减少冗余下刷消息的路由下刷方案。
(?)提出了实际的测试方案,对本项目的SPT切换功能进行了测试,证明了本文所设计方案的可行性。最后分析了项目存在的问题,提出了改进意见和来工作方向。
With the increasing development of three networks convergence in our country, the multimedia service like IPTV has been getting greatly improved. Multimedia service has some particular characteristics like high bandwidth consumption which stimulates the development and popularity of IP multicast. The crucial technology of IP multicast is multicast routing which has varieties of multicast routing protocals. Among those protocals, PIM-SM has become most popular due to its advantages such as user taking initiative to join, pan flood control and multicast not limited to a domain.
Based on the study of PIM-SM, this paper introduces a distributing implementation scheme of PIM-SM. The idea of the scheme is that the control plane and the data plane of PIM-SM are separately implemented. The protocal control is implemented in the control plane and the data forwarding is implemented in the data plane. The biggest problem is how to assure coherence between control plane and data plane. It introduces a routing synchronization scheme through offsetting algorithm to solve the problem. After a practical testing, the scheme can guarantee the same routing information in control plane and data plane. In short, it is an efficient and feasible routing synchronization scheme. The contents contained are below:
(?) Forwarding characteristic and IP multicast architecture are analyzed. The principles and features of PIM-SM are analyzed.
(?) Based on the architecture of Comware system and the characteristics of PIM-SM, it introduces a distributing implementation scheme.
(?) It analyzes the problem of plane coherence. Based on the implementation structure, it introduces a inner communication mechanics of Comware to solve the problem. It introduces a routing synchronization scheme through offsetting algorithm to solve the problem.
(?) Practical testing plan is given. The scheme of PIM-SM proves to be feasible in term of performance. Finally, it analyzes the existing problems and advances the betterment opinion and future work area.
引文
[1]马戈芳,徐明伟.IPv6组播技术综述.电信技术.2003(7)：23-26
[2]D. Waitzman, S. Deering. RFC1075, Distance Vector Multicast Routing Protocol. 1988.
[3]S. Deering. RFC1112, Host Extensions for IP Multicasting.1989.
[4]B. Cain. RFC3376, Internet Group Management Protocol, Version 3.2002.
[5]T. Bates. RFC4760, Multiprotocol Extensions for BGP-4.2007.
[6]B. Fenner. RFC3618, Multicast Source Discovery Protocol (MSDP).2003.
[7]B. Fenner, M. Handley, H. Holbrook, I. Kouvelas. RFC4601, Protocol Independent Multicast-Sparse Mode (PIM-SM).2006.
[8]Christian Huitema. IPv6:The New Internet Protocol第1版北京：清华大学出版社,1999.
[9]魏亮.高端路由器现状及新进展www.cww.net.cn,2003.
[10]曹佳,鲁士文.组播技术研究.信息技术快报.2004(11)：32-38
[11]宋阳.架构决定品质www.ccidnet.com.2004.
[12]冯渊.T比特路由器上PIM_SM协议实现研究.郑州：解放军信息工程大学.2005.
[13]W. Richard Stevens. TCP/IP详解卷1：协议.北京：机械工业出版社.2000.
[14]P. Radoslavov. RFC2909, The Multicast Address-Set Claim (MASC) Protocol. 2000.
[15]S. Hanna, B. Patel, M. Shah. RFC2730, Multicast Address Dynamic Client Allocation Protocol (MADCAP).1999.
[16]M. Handley. RFC5015, Bidirectional Protocol Independent Multicast (BIDIR-PIM).2007.
[17]闲云.组播技术白皮书.当代通信.2003(9)：28～33
[18]R. Vida, L. Costa. RFC3810, Multicast Listener Discovery Version 2 (MLDv2) for IPv6.2004.
[19]J. Moy. RFC 1584, Multicast Extensions to OSPF.1994.
[20]A. Ballardie. RFC2189, Core Based Trees (CBT version 2) Multicast Routing. 1997.
[21]杨余旺,蓝少华.域内域间和自组网IP组播路由协议分析.计算机与现代化. 2003(12):19～21
[22]A. Adams, J. Nicholas, W. Siadak. RFC3973, Protocol Independent Multicast Dense Mode (PIM-DM).2005.
[23]S. Bhattacharyya. RFC3569, An Overview of Source-Specific Multicast (SSM). 2003.
[24]刘春江.IPv6网络中组播路由——PIM技术研究.光通信研究.2006(2)：29～31
[25]岩延,郭江涛.组播路由协议设计及应用.北京：人民邮电出版社.2002.
[26]N. Bhaskar. RFC5059, Bootstrap Router (BSR) Mechanism for Protocol Independent Multicast (PIM).2008.
[27]陆正福,王敏Bi_PIM协议的原理分析及其Petri网模型.计算机工程.2004(2)：124～126
[28]孟祥迪,郭静寰.基于Anycast RP的组播源发现协议在单一PIM域中的研究与实现.计算机应用与软件.2009(6)：216～217
[29]肖秧琳.高性能路由器域间组播的实现技术研究.计算技术与自动化.2006(1)：73～76
[30]张悦.基于L3 VPN的域间组播研究.北京：北京交通大学.2005.
[31]王飓.走进网络操作系统——Comware软件架构浅谈http://www.h3c.com.cn/About_H3C/Company_Publication/IP_Lh/2008/One/Ho me/Catalog/200906/637801_30008_0.htm,2009-06-18.
[32]K. Ravindran and Ting-Jian Gong. Cost analyseis of multicast transport architectures in multiservice networks. IEEE/ACM Trans on Networking. 1998(1):94～109
[2]D. Waitzman, S. Deering. RFC1075, Distance Vector Multicast Routing Protocol. 1988.
[3]S. Deering. RFC1112, Host Extensions for IP Multicasting.1989.
[4]B. Cain. RFC3376, Internet Group Management Protocol, Version 3.2002.
[5]T. Bates. RFC4760, Multiprotocol Extensions for BGP-4.2007.
[6]B. Fenner. RFC3618, Multicast Source Discovery Protocol (MSDP).2003.
[7]B. Fenner, M. Handley, H. Holbrook, I. Kouvelas. RFC4601, Protocol Independent Multicast-Sparse Mode (PIM-SM).2006.
[8]Christian Huitema. IPv6:The New Internet Protocol第1版北京：清华大学出版社,1999.
[9]魏亮.高端路由器现状及新进展www.cww.net.cn,2003.
[10]曹佳,鲁士文.组播技术研究.信息技术快报.2004(11)：32-38
[11]宋阳.架构决定品质www.ccidnet.com.2004.
[12]冯渊.T比特路由器上PIM_SM协议实现研究.郑州：解放军信息工程大学.2005.
[13]W. Richard Stevens. TCP/IP详解卷1：协议.北京：机械工业出版社.2000.
[14]P. Radoslavov. RFC2909, The Multicast Address-Set Claim (MASC) Protocol. 2000.
[15]S. Hanna, B. Patel, M. Shah. RFC2730, Multicast Address Dynamic Client Allocation Protocol (MADCAP).1999.
[16]M. Handley. RFC5015, Bidirectional Protocol Independent Multicast (BIDIR-PIM).2007.
[17]闲云.组播技术白皮书.当代通信.2003(9)：28～33
[18]R. Vida, L. Costa. RFC3810, Multicast Listener Discovery Version 2 (MLDv2) for IPv6.2004.
[19]J. Moy. RFC 1584, Multicast Extensions to OSPF.1994.
[20]A. Ballardie. RFC2189, Core Based Trees (CBT version 2) Multicast Routing. 1997.
[21]杨余旺,蓝少华.域内域间和自组网IP组播路由协议分析.计算机与现代化. 2003(12):19～21
[22]A. Adams, J. Nicholas, W. Siadak. RFC3973, Protocol Independent Multicast Dense Mode (PIM-DM).2005.
[23]S. Bhattacharyya. RFC3569, An Overview of Source-Specific Multicast (SSM). 2003.
[24]刘春江.IPv6网络中组播路由——PIM技术研究.光通信研究.2006(2)：29～31
[25]岩延,郭江涛.组播路由协议设计及应用.北京：人民邮电出版社.2002.
[26]N. Bhaskar. RFC5059, Bootstrap Router (BSR) Mechanism for Protocol Independent Multicast (PIM).2008.
[27]陆正福,王敏Bi_PIM协议的原理分析及其Petri网模型.计算机工程.2004(2)：124～126
[28]孟祥迪,郭静寰.基于Anycast RP的组播源发现协议在单一PIM域中的研究与实现.计算机应用与软件.2009(6)：216～217
[29]肖秧琳.高性能路由器域间组播的实现技术研究.计算技术与自动化.2006(1)：73～76
[30]张悦.基于L3 VPN的域间组播研究.北京：北京交通大学.2005.
[31]王飓.走进网络操作系统——Comware软件架构浅谈http://www.h3c.com.cn/About_H3C/Company_Publication/IP_Lh/2008/One/Ho me/Catalog/200906/637801_30008_0.htm,2009-06-18.
[32]K. Ravindran and Ting-Jian Gong. Cost analyseis of multicast transport architectures in multiservice networks. IEEE/ACM Trans on Networking. 1998(1):94～109
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