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Glossary

IP Multicast Stub Routing in AOS

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Copyright © 2005 ADTRAN, Inc.

61200890L1-29.3A

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Содержание IP Multicast

Страница 1: ... many messages This document provides a high level description of IP multicast and describes the multicast features introduced in the ADTRAN Operating System AOS Release 7 1 For more detailed information regarding specific command syntax refer to the AOS Command Reference Guide on your ADTRAN OS Documentation CD This guide consists of the following sections IP Multicast Overview on page 2 IP Multi...

Страница 2: ...e conducted at scheduled times from the central university campus and the live audio and video streams are made available via the media server To join a class the student logs into a computer at the satellite classroom and selects a URL opening a media player and pointing it to the appropriate content on the media server The media server configures the media player for the content s stream format ...

Страница 3: ...lticast Overview 61200890L1 29 3A Copyright 2005 ADTRAN Inc 3 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 ...

Страница 4: ...wish to receive this multicast address In multicast speak these PCs have joined the multicast group identified by that multicast address The satellite routers use a multicast routing protocol most likely PIM to signal other routers in the backbone and the Central Router that they have receivers for that multicast group Each router in the network then understands if it is in the path toward receive...

Страница 5: ...ntent 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 resulting in the stream being sent multiple times over the same physical interface ...

Страница 6: ...cast address is that only devices running a process that uses a given multicast address need listen for the address Other devices are not interrupted when a multicast address is transmitted With broadcast addressing all attached devices are interrupted to listen to a broadcast packet whether they need it or not All devices that wish to receive the same IP multicast content are referred to as a gro...

Страница 7: ...ting protocols PIM Protocol Independent Multicast is the most common The following sections contain short descriptions of several multicast routing protocols Some important concepts for multicast routing protocols include Source based or shared trees Dense or sparse mode Reverse path flooding Pruning The methods used by each protocol are listed below but a detailed definition is beyond the scope o...

Страница 8: ...l in use and eventually to the Central Router 5 IP packets from the Media Server to the group address 224 1 1 1 then flow through the backbone and ultimately to PC1 While the multicast routing protocol does not consume significantly more bandwidth relative to other solutions it does consume CPU and memory resources on the stub router even though it is performing only a portion of its total job due...

Страница 9: ... dial backup where either the primary link or the backup link is active at any given time In situations where there is more than one simultaneously active link to the multicast network used for redundancy load sharing meshing etc it may be possible through extremely careful network design to use IGMP forwarding However a multicast routing protocol is strongly recommended to protect against loops a...

Страница 10: ...onfigured only one will be selected to serve as the current upstream interface for IGMP Forwarding This works well in situations such as dial backup when either the primary or the backup interface is operational at any one time Topologies with multiple operational upstream interfaces such as dual PVCs or PPP links to the multicast network require special care since there is no automatic protection...

Страница 11: ...the backup interface is down and the primary is selected as the IGMP forwarding interface and performs the IGMP host function When PC1 wishes to receive the media server stream being transmitted on group address 224 1 1 1 it sends an IGMP message on its segment indicating it wishes to join that group The AOS router registers that group address on interface eth 0 1 Since eth 0 1 is set with IGMP he...

Страница 12: ...IP Multicast Stub Routing in the AOS IP Multicast Stub Routing in AOS 12 Copyright 2005 ADTRAN Inc 61200890L1 29 3A Figure 3 AOS Multicast Stub and IGMP Forwarding Support ...

Страница 13: ...ing int s0 1 PVC to the stub router other configuration details omitted ip address 10 0 0 2 255 255 255 0 ip pim sparse dense mode AOS as Stub Router ip multicast routing ip mcast stub helper address 12 1 1 1 ip address of the media server int eth 0 1 ip address 10 1 0 1 255 255 255 0 ip mcast stub downstream ip mcast stub helper enabled int eth 0 2 ip address 10 2 0 1 255 255 255 0 ip mcast stub ...

Страница 14: ...ess specified With other products that use multicast stub functionality PIM must still be turned on to enable multicast forwarding on all involved interfaces and to enable IGMP on downstream interfaces In AOS multicast stub operation has unique commands that enable only the functions necessary for multicast stub operation wasting no CPU memory or bandwidth resources on a routing protocol that is h...

Страница 15: ...a dial backup link when the primary fails Q5 What versions of IGMP does AOS 7 x support A5 AOS 7 x supports IGMP Versions 1 and 2 Q6 Can a multicast source be connected to an AOS 7 x router A6 In AOS 7 x a locally connected multicast source can be connected but only locally connected receivers can join the group AOS will not forward local sources upstream toward the multicast enabled network In ot...

Страница 16: ...t specific group address Group Address The IP multicast address to which a specific multicast stream is transmitted Somewhat analogous to the frequency on which a particular TV or radio channel is transmitted End devices use IGMP to join subscribe a specific group to receive packets transmitted to that group address In doing so they become group members IGMP Internet Group Management Protocol Used...

Страница 17: ...ble is populated Receiver See Listener Source A device that originates multicast packets to be received by one or more receivers Stream The flow of information being sent by a multicast source to a specific group of receivers For certain content types e g audio video etc the stream may be a constant flow For other content types e g data software updates etc the flow may be sporadic Stub Network A ...

Страница 18: ...Glossary IP Multicast Stub Routing in AOS 18 Copyright 2005 ADTRAN Inc 61200890L1 29 3A ...

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