Interdomain Multicast Routing: Practical Juniper Networks and Cisco Systems Solutions
Brian M. Edwards, Brian Joseph Wright, John W. Stewart · CERN Document Server (European Organization for Nuclear Research) · 2002
From the Book: Interdomain Multicast Routing is a work on a timely technology of multicasting and is written with the network engineer in mind who is responsible for configuring and maintaining that capability within their network. It is meant to be a practical reference guide that includes Cisco and Juniper Networks technology. The authors' goals are to explain the rationale and benefits of multicast routing on the Internet, to include the two leading vendors of routers and routing technology and note how they differ when applying multicast routing, and to explain the underpinnings of multicasting in simple, clear language. For a preview of the topics within this book, the following chapter listings detail their topic matter. Chapter 1, Interdomain Multicast Fundamentals, begins with a definition of multicast transmission of data in contrast to other means of data delivery, within and outside the Internet, then provides an introductory explanation of some of the issues affecting successful routing of multicast traffic on the Internet. Those seeking to understand the enormous potential for multicast may wish to tune in directly to this section. Chapter 2, IMR Overview, is a general description of how to generate and receive multicast traffic, including description of methods for routers to detect sources and receivers of multicast traffic. The discussion then proceeds from multicast single-domain routing using PIM-SM (Protocol Independent Multicast-Sparse Mode) to multicast routing using MSDP (Multicast Source Discovery Protocol). Chapter 3, Multicast Routing Protocols, describes the main features of theprotocols. Chapter 4, Protocol Independent MulticastSparse Mode, lays out PIM-SM, the predominant multicast routing protocol for routing. Since PIM-SM is commonly used in the initial sequence of activities that gets multicast up and running within a single domain, the procedure dominates the scope of this chapter. PIM messages for both version 1 and version 2 of the protocol are covered, as is the use of Anycast Rendezvous Point (RP) to improve load balancing and redundancy. Ample numbers of diagrams and corresponding examples describe distribution tree construction and teardown for various delivery models, and the chapter ends with a discussion of multicast scoping. Multicast Source Discovery Protocol (MSDP) is then treated, in Chapter 5: MSDP, which shows how to use MSDP to connect multiple PIM-SM domains. MSDP is the most commonly deployed anysource multicast (ASM) mechanism for giving Internet multicast routing its interdomain reach. With MSDP, each PIM-SM domain has its own RP and does not rely on the RP of another organization's network. This chapter contains a number of illustrations for the rules that determine the reverse path forwarding (RPF) peer, a necessity in MSDP. It concludes with sections on mesh groups, susceptibility to operational problems, and a discussion of the prospects for the widely used MSDP vis a vis upcoming versions of (Border Gateway Multicast Protocol) BGMP. Chapter 6, Source-Specific Multicast (SSM), is an critical component of the book, which discusses issues affecting implementations and maintenance of ASM IMR, because the job of source discovery of multicast traffic for willing recipients when sources are potentially many, i.e., the many-source to many-recipient model, is a major challenge for today's modern networks. However, recognizing the greatest commercial use of Internet multicast as a one-to-many model, where the recipient/subscriber explicitly designates the source, network engineers developed SSM to make everyone's life easier. Further, knowing how to configure SSM provides the basis for learning the more complex world of ASM. Chapter 7 and Chapter 8 cover Multiprotocol Extensions to Border Gateway Protocol (MBGP) and Multitopology Routing in Intermediate System to Intermediate System (M-ISIS), respectively. MBGP and M-ISIS can be used side-by-side to build a dedicated multicast RPF table, just as BGP and ISIS have traditionally coexisted in unicast intra-AS and inter-AS environments. These chapters focus on how to create two separate virtual topologies, one for unicast and one for multicast. The remaining chapters of IMR critically cover hands-on, real-world examples and tools. Chapters 9 and 10 are, respectively, practical methods and guidelines for actually configuring and verifying multicast routing on Juniper Networks and Cisco routers. Chapter 11 provides a representative case study for native deployment of IMR by an ISP; Juniper Networks and Cisco router configurations for all router roles in this example network are also set forth. Chapter 12 discusses management tools for multicast networks, chiefly Simple Network Management Protocol (SNMP) and the mtrace traceroute facility for IP multicast. Chapter 13 covers related topics, mainly the imminence of BGMP with incorporation of Multicast Address Set Claim (MASC) Protocol mapping, bidirectional PIM, and use of Realtime Transport Protocol (RTP) for host-to-host transport over IP networks where realtime applications such as video and audio streaming are suited. The Appendices list packet formats for IGMP, PIM, and MSDP. Finally, because any brave new world of knowledge only cones to be mastered by intelligent use and definition of its key concepts, we spent a considerable amount of time gathering and refining pertinent terminology: We hope the Glossary of Terms clarifies key acronyms and definitions, and even serves to stimulate dialog leading to more exact conceptual rendering of terms down the line, in future iterations of the book.