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61200890L1-29.3A
March 2005
Configuration Guide
IP Multicast Stub Routing in AOS
Overview and Examples for IP Multicast Technology
IP multicast provides an efficient method for delivering common
information from a single source to multiple recipients without unnecessary
duplication and network resource waste. It is most often associated with the
delivery of media content such as video and audio, but may also be used to
deliver data such as news, stock tickers, and other one-to-many messages.
Thi
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IP Multicast Overview IP Multicast Stub Routing in AOS IP Multicast Overview IP multicast has many applications, ranging from video and/or audio program delivery, music-on-hold for an IP PBX, conferencing applications, and delivery of software updates, data, or other information to multiple sites and/or devices. This document uses simple example applications to illustrate the various components of IP multicast. Satellite Classroom Example The following example describes a one-to-many application
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IP Multicast Stub Routing in AOS IP Multicast Overview Figure 1. Non-Multicast Network PCs 1, 2, 4, and 6 have subscribed to a specific media server content which is delivered with a separate unicast stream for each subscribing client PC. 61200890L1-29.3A Copyright © 2005 ADTRAN, Inc. 3
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IP Multicast Overview IP Multicast Stub Routing in AOS Satellite Classroom Application on a Multicast-Enabled Network In a multicast-enabled network, the media server sends specific content in a single stream to a specific multicast IP address, much like a local broadcast TV station sends its content on a specific broadcast frequency. The network has multicast intelligence and is able to make copies of the stream as necessary to reach all active receivers. This provides two significant efficienc
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IP Multicast Stub Routing in AOS IP Multicast Overview Figure 2. Multicast-Enabled Network PCs 1, 2, 4, and 6 have subscribed to a specific media server content which is delivered on a single multicast stream and copied once to each segment containing subscribing client PCs. When using subinterfaces (frame relay PVCs, VLAN subinterfaces, etc.), each subinterface is a separate logical IP interface. It is possible that a multicast stream may be forwarded to each subinterface,
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IP Multicast Addressing and Protocols IP Multicast Stub Routing in AOS IP Multicast Addressing and Protocols Multicast Addressing The IPV4 address scheme (layer 3) sets aside Class D addresses for use in IP multicast. RFC1112 discusses multicast addressing in detail. The Class D range is from 224.0.0.0 through 239.255.255.255. The range from 224.0.0.0 through 224.0.0.255 is reserved for local administrative or maintenance use and is usually limited to the scope of a single subnet. In other words
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IP Multicast Stub Routing in AOS IP Multicast Addressing and Protocols routers (ultimately reaching the router connected to the source of the multicast stream). This allows a distribution tree to be built from the source to all receivers, thus ensuring the following: There is a path to all receivers. No stream is sent where there are no receivers. There are no loops in the distribution tree. The proper path is used between a source and a receiver. These are critical factors in building a
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IP Multicast in Stub Topologies IP Multicast Stub Routing in AOS IP Multicast in Stub Topologies A stub network is a portion of a network with a single connection to the remainder of the network. The spokes in a hub-and-spoke network are a common form of stub network, although there are other forms. In the stub portion of a network, a multicast routing protocol is not necessary for IP multicast operation. Since there is a single link, there is a single best path and no potential for a loop. All
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IP Multicast Stub Routing in AOS IP Multicast in Stub Topologies to the multicast-enabled network (the backbone in Figure 2). The connection to the backbone is the stub router’s upstream connection. The connection to the classroom LAN is the stub router’s downstream connection. A downstream connection faces multicast clients (PCs in Figure 2) and performs the IGMP router function as would a typical multicast router. The upstream connection faces the multicast network and would normally run a m
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IP Multicast Stub Routing in the AOS IP Multicast Stub Routing in AOS IP Multicast Stub Routing in the AOS In Release 7.1, AOS introduced IP multicast support in the form of IP Multicast Stub Routing using IGMP Forwarding. Note the following key points for this release: AOS command syntax differs from some other vendors when configuring this feature. In other vendor implementations, multicast forwarding, PIM, and IGMP functions are intertwined. By enabling PIM on an interface, you also enable
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IP Multicast Stub Routing in AOS IP Multicast Stub Routing in the AOS Helper Address Technical Note The helper address can be any address on the path from the desired upstream interface to the multicast-source device. The choice depends on several network design parameters such as: Where the upstream interface(s) connect in the multicast network. The number and location of sources in the multicast network. The granularity of network routes in the stub router’s unicast routing table. If usi
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IP Multicast Stub Routing in the AOS IP Multicast Stub Routing in AOS Figure 3. AOS Multicast Stub and IGMP Forwarding Support 12 Copyright © 2005 ADTRAN, Inc. 61200890L1-29.3A
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IP Multicast Stub Routing in AOS Example Configuration Example Configuration In the following example, Router 1 is assumed to be a non-AOS product configured with an operating system common to other vendors, and the Stub Router is an AOS product. Though not shown in Figure 3 on page 12, the Stub Router receives a default route from the peer router through whichever interface is currently connected (primary or secondary). Othervendoras Router1: ip multicast-routing int s0.1 (PVC to the stub route
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Key Differences in Multicast Stub Routing IP Multicast Stub Routing in AOS Key Differences in Multicast Stub Routing The key differences between AOS multicast stub routing and that of some other common product operating systems are as follows: In AOS, the multicast helper address is a single global setting. Each downstream interface can be configured to use or not use IGMP forwarding. In some other products, each interface may have a separate helper address specified. With other products tha
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IP Multicast Stub Routing in AOS Frequently Asked Questions (FAQs) Frequently Asked Questions (FAQs) Q1: What multicast applications does AOS support? A1: AOS 7.x (and later) supports local IP multicast (source and receivers attached to local router interfaces) and IP multicast in stub networks using IGMP forwarding. Q2: What is a stub network and why is it important in this application? A2: A stub network is one that has a single connection to the remainder of the network. A router with two PVC
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Glossary IP Multicast Stub Routing in AOS Glossary Broadcast: A transmission addressed to all receivers, usually contained within the given broadcast domain. Broadcast Domain: A layer 2 domain, separated by layer 3 devices (routers). A VLAN or LAN segments connected layer 2 switches and/or bridges typically form a broadcast domain. An IP subnet is typically contained within a broadcast domain. Content: The information being conveyed by a source via transmission of a multicast stream. Downstream:
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IP Multicast Stub Routing in AOS Glossary Multicast: A transmission sent to a specific set of receivers. Multicast Routing: The ability to determine the proper loop-free paths on which to forward multicast packets such that all subscribing listeners receive the stream without wasting network resources. PIM: Protocol Independent Multicast. A multicast routing protocol that uses the unicast routing table with no concern of how the routing table is populated. Receiver:See Listener. Source: A device
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Glossary IP Multicast Stub Routing in AOS 18 Copyright © 2005 ADTRAN, Inc. 61200890L1-29.3A
