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Allied Telesis AR400 manual Explanation of IGMP fast leave, Page 63 AlliedWare OS How To Note IGMP

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IGMP fast leave > Explanation of IGMP fast leave

Explanation of IGMP fast leave

Imagine that client 2 on switch 3 sends a Membership Report to join the group 224.12.13.14. The Snooper, switch 3, adds this to its the IGMP snooping table. When the same client then sends a Leave message, the IGMP Querier responds with a Membership Query and waits for a configured time for a response.

The next sections describe in detail the differences between having Fast Leave disabled and enabled, but in summary:

zWithout Fast Leave, the IGMP Snooper waits the same length of time as the Querier, then expires the entry if there was no response.

zWith Fast Leave, the IGMP Snooper expires the entry as soon as it sees the Leave message from the client. By the time the Querier sends the Membership Query, the Snooper will have already expired the entry and therefore stopped sending the stream to the client.

Page 63 AlliedWare™ OS How To Note: IGMP

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Allied Telesis AR400 manual Explanation of IGMP fast leave, Page 63 AlliedWare OS How To Note IGMP

Contents

Contents IntroductionAlliedWare OS Snooper timer values Why convergence takes so long without query solicitationEnabling query solicitation on multiple switches in a looped topology Querier timer valuesProducts and software versions this note applies to IGMP feature For most examples in this How To Note, we usedz one AT-8948 switch, with Software Version z two Rapier 24i switches, with Software VersionQueriers and Snoopers IGMP overviewMessages Choosing group addresses Page 8 AlliedWare OS How To Note IGMP Avoid x.0.0.y, x.0.1.y, x.128.0.y, and x.128.1.yExample IGMP snoopingPage 10 AlliedWare OS How To Note IGMP X Configure switchX Configure switch X Configure switchprocess Explanation of IGMP snoopingigmpsnooping on the Snooper Using Show command output to investigate IGMP stateNext, look at the output of the command show ip igmp on the Querier Page 13 AlliedWare OS How To Note IGMPThis output now shows two entries, one for each of the following Page 14 AlliedWare OS How To Note IGMP When a client leaves a groupMultiple potential IGMP queriers Page 15 AlliedWare OS How To Note IGMPExample Page 16 AlliedWare OS How To Note IGMP X Configure switchX Configure switch X Configure switchExplanation of Multiple potential IGMP queriers When there are no group membersPage 18 AlliedWare OS How To Note IGMP When a client joins a groupRefresh time 228 secs Page 19 AlliedWare OS How To Note IGMPPage 20 AlliedWare OS How To Note IGMP IGMP proxy Page 21 AlliedWare OS How To Note IGMPExample Switch 3 is an IGMP Proxy X Configure switchX Configure switch X Configure switchPage 23 AlliedWare OS How To Note IGMP Explanation of IGMP proxyWhen there are no group members When a client joins a groupRefresh time 243 secs Page 24 AlliedWare OS How To Note IGMPPage 25 AlliedWare OS How To Note IGMP When a client leaves a groupHow query solicitation works Query solicitation rapid recovery from topology changesQS and sends Initial stateTC and sends Query Solicit QSX Configure switch Why convergence takes so long without query solicitationExample X Configure switchExplanation from the perspective of switch 2, the snooper Page 30 AlliedWare OS How To Note IGMP When link comes up againshows this entry Explanation from the perspective of switch 1, the querieragain forwarding the multicast stream out the port Speeding up IGMP convergence in a non-looped topology Enabling query solicitation on multiple switches in a looped topologySwitch 1 sends GQ from switchSwitch 2 sends QS to switchExample IGMP filtering controlling multicast distributiontypes command X Configure switchX Configure switch X Configure switchPage 37 AlliedWare OS How To Note IGMP Dropped Explanation of IGMP filtering controlling multicast distributionReceived PassedPage 39 AlliedWare OS How To Note IGMP Example IGMP throttling limiting the number of streams for each subscriberX Configure switch X Configure switchPage 41 AlliedWare OS How To Note IGMP Page 42 AlliedWare OS How To Note IGMP X Configure switchConsider switch 2 after a client on port 2 has joined six groups from Page 44 AlliedWare OS How To Note IGMP Note that the group list is sorted by refresh time, not group address X Modify switch 2 Configuration When we deny groups instead of replacing themPage 47 AlliedWare OS How To Note IGMP Static IGMP Page 48 AlliedWare OS How To Note IGMPExample Switch 2 is an IGMP Snooper X Configure switchX Configure switch z enable IGMP z enable the interface as an IGMP interfacePage 50 AlliedWare OS How To Note IGMP X Configure switchPage 51 AlliedWare OS How To Note IGMP Explanation of Static IGMPX Modify switch 3 Configuration When we add a static entry on another switchPage 53 AlliedWare OS How To Note IGMP Page 54 AlliedWare OS How To Note IGMP port=5,26 counter X Modify switch 3 ConfigurationPage 55 AlliedWare OS How To Note IGMP MulticastPkts Page 56 AlliedWare OS How To Note IGMPMulticastPkts 36350Page 57 AlliedWare OS How To Note IGMP When a static entry’s port goes downHow clients leave groups queries and timers Querier timer valuesOverview of leave process Snooper timer values Consequences for high-loss and high-lag networks Comparing the Querier and Snooper timersset igmpsnooping vlan=vlanx fastleave=onoff IGMP fast leaveExample set igmpsnooping fastleave=onoff interface=vlanxPage 62 AlliedWare OS How To Note IGMP X Configure switchX Configure switch X Configure switchPage 63 AlliedWare OS How To Note IGMP Explanation of IGMP fast leavePage 64 AlliedWare OS How To Note IGMP When fast leave is disabledIt is safe to ignore the group entry on switch When you enable fast leave on switchSimilarly, we can easily disable Fast Leave on all interfaces When you set fast leave on all interfacesMultiple host mode for fast leave Page 68 AlliedWare OS How To Note IGMP z Initial configuration on page z Default values on page Configurable IGMP timers and countersTimer and counter relationships z Timer and counter relationships on page z Software versions on pageSoftware versions Initial configurationConfigurable IGMP timers and counters Initial configuration X Configure switchX Configure switch X Configure switchDefault values Last Member Query Count and Last Member Query IntervalWhat these counters do 1/10secs Potential problems with changing these countersHow to change these counters Last Member Query IntervalLast Member Query Count Page 74 AlliedWare OS How To Note IGMPWhat this counter does Potential problems with changing this counterHow to change this counter Robustness VariableHow to change this timer Default Query IntervalWhat this timer does Potential problems with changing this timerHow to change this timer Query Response IntervalWhat this timer does Potential problems with changing this timerPotential problems with changing this timer Default Timeout IntervalSynchronisation of timers What this timer doesNext, change the Default Query Interval to 130 seconds Increase Default Query IntervalDefaults First, the following output shows the default settings The Default Timeout Interval = 2*125 + 100/10 = 260 secondsPage 80 AlliedWare OS How To Note IGMP Increase Query Response IntervalPage 81 AlliedWare OS How To Note IGMP Override Default Timeout IntervalDefault Timeout Interval = Default Timeout Interval = 2 * 200 + 10 = 410 secondsPage 82 AlliedWare OS How To Note IGMP set ip igmp timeout=126 Example of bad choices for timer valuesTimer Default Timeout IntervalProblem 1 Last Member Query Interval too short Problem 2 Query Response Interval shortProblem 3 Default Timeout Interval too short not recommend this For more information, see Synchronisation of timers on pageStopping snoopers from snooping non-IGMP messages ExampleOSPF Page 87 AlliedWare OS How To Note IGMP X Configure switchX Configure switch X Configure switchX Configure the router Page 89 AlliedWare OS How To Note IGMP Ports 25Ports Disabling All Groups entry for a port Preventing an All Groups entry for a port1. Permit port 24 to be an All Groups port again 2. Check the group entry timeout values3. Reset port 24’s packet counters Enabling All Groups entry againPage 92 AlliedWare OS How To Note IGMP 5. Check the group entry timeout values again6. Enable IGMP debugging 8. Check the group entry timeout values againPage 93 AlliedWare OS How To Note IGMP It is most likely that the group entry will time out first z the ports internal timer hits zero and is refreshedPage 94 AlliedWare OS How To Note IGMP z the streams group entry times out and is refreshed, orControlling which addresses create All Groups entries This optionpackets from Configuring switch set igmpsnooping routermode=ipdelete igmpsnooping routeraddress=224.0.0.5 Page 97 AlliedWare OS How To Note IGMP Configuring switches 1 and Adding other router addressesPage 98 AlliedWare OS How To Note IGMP To return to the default list, change the router mode to default Returning to the default listPage 100 AlliedWare OS How To Note IGMP Using the other routermode optionsStatically specifying that a port is a router port 2. Check the current IGMP snooping entriesExample 3. Statically add port 6 as a router port attached to VLAN 4. Stop port 6 from being a static router portTo remove the static configuration, simply delete it IGMP debugging X A client joins a groupExample X A client leaves a group X A port entry times out X Snooped ports changePage 105 AlliedWare OS How To Note IGMP X A report is filtered out X A port in the All Groups list is unpluggedPage 106 AlliedWare OS How To Note IGMP Page 107 AlliedWare OS How To Note IGMP X Output for show ip igmp changesAppendix STP state SwitchPage 109 AlliedWare OS How To Note IGMP SwitchUSA Headquarters 19800 North Creek Parkway Suite 100 Bothell WA 98011 USA T +1 800 424 4284 F +1 425 481 Switch