This enables them to send the correct multimedia streams to the correct destination. This How To Note describes basic and advanced IGMP configuration, in the following major sections: • an overview of IGMP and definitions of some of the IGMP terminology • examples and discussion of the most common IGMP functionality—IGMP snooping, IGMP Querier behaviour and selection, and IGMP proxy • examples and discussion of the advanced functionality available through AlliedWare’s feature-rich IGMP implementation • information for debugging • information about the STP state of the simple three-switch ring used in most examples Contents Introduction .............................................................................................................................................. 1 Products and software versions this note applies to ............................................................... 3 IGMP overview ......................................................................................................................................... 5 Queriers and Snoopers .................................................................................................................. 5 Messages ............................................................................................................................................. 6 Choosing group addresses ............................................................................................................. 7 IGMP snooping ......................................................................................................................................... 9 Example .............................................................................................................................................. 9 Explanation of IGMP snooping .................................................................................................... 11 C613-16087-00 REV C Introduction > Contents Multiple potential IGMP queriers ...................................................................................................... 15 Example ............................................................................................................................................ 15 Explanation of multiple potential IGMP queriers .................................................................... 17 IGMP proxy ............................................................................................................................................. 21 Example ............................................................................................................................................ 21 Explanation of IGMP proxy .......................................................................................................... 23 Query solicitation (rapid recovery from topology changes) ....................................................... 26 How query solicitation works ..................................................................................................... 26 Why convergence takes so long without query solicitation ................................................ 28 Speeding up IGMP convergence in a non-looped topology ................................................. 33 Enabling query solicitation on multiple switches in a looped topology ............................. 33 IGMP filtering (controlling multicast distribution) ......................................................................... 35 Example ............................................................................................................................................ 35 Explanation of IGMP filtering (controlling multicast distribution) ...................................... 38 IGMP throttling (limiting the number of streams for each subscriber) .................................... 40 Example ............................................................................................................................................ 40 Explanation of IGMP throttling (limiting the number of streams for each subscriber) . 43 Static IGMP ............................................................................................................................................. 48 Example ............................................................................................................................................ 48 Explanation of Static IGMP .......................................................................................................... 51 How clients leave groups: queries and timers ................................................................................ 58 Overview of leave process ........................................................................................................... 58 Querier timer values .............................................................................................................