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Allied Telesis AR400 manual When link comes up again, Page 30 AlliedWare OS How To Note IGMP

Models: AR400

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When link comes up again

Query solicitation (rapid recovery from topology changes) > Why convergence takes so long without query solicitation

When link comes up again

When we reconnect port 1 on the Snooper, the All Groups entry does not reappear.

Manager Switch 2> show igmpsnooping

IGMP Snooping

------------------------------------------------------------------------

Status	Enabled
Disabled All-groups ports	........ None
Vlan Name (vlan id) ..... default (1)
Fast Leave	Off
Query Solicitation	Off
Static Router Ports ..... None
Group List
Group. 224.12.13.14	Entry timeout 140 secs
Ports 9

------------------------------------------------------------------------

Eventually, the Querier sends an IGMP Query, which the Snooper receives on port 1. This restores the All Groups port on the Snooper. By default the Querier sends General Queries every 125 seconds, so the IGMP convergence delay will be up to 125 seconds with the default settings. For more information about this timeout, see "Configurable IGMP timers and counters" on page 69—but do not change the timeout without very carefully considering the effect on your network.

Manager Switch 2> show igmpsnooping

IGMP Snooping

------------------------------------------------------------------------

Status	...........................	Enabled
Disabled All-groups ports		........ None
Vlan Name (vlan id) ..... default (1)
Fast Leave		Off
Query Solicitation		Off
Static Router Ports ..... None
Group List
Group. 224.12.13.14		Entry timeout 107 secs
Ports	9
All Groups		Entry timeout 236 secs
Ports	1

------------------------------------------------------------------------

When the Snooper receives the General Query, it forwards it out all its ports. The client responds with a Report. The Snooper forwards the Report out its All Groups port towards the Querier. The Querier responds by sending the multicast stream to the Snooper, which forwards the multicast stream out port 9 to the client.

Page 30 AlliedWare™ OS How To Note: IGMP

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Allied Telesis AR400 manual When link comes up again, Page 30 AlliedWare OS How To Note IGMP

Contents

Contents IntroductionAlliedWare OS Querier timer values Why convergence takes so long without query solicitationEnabling query solicitation on multiple switches in a looped topology Snooper timer valuesProducts and software versions this note applies to z two Rapier 24i switches, with Software Version For most examples in this How To Note, we usedz one AT-8948 switch, with Software Version IGMP featureIGMP overview Queriers and SnoopersMessages Choosing group addresses Avoid x.0.0.y, x.0.1.y, x.128.0.y, and x.128.1.y Page 8 AlliedWare OS How To Note IGMPIGMP snooping ExampleX Configure switch X Configure switchX Configure switch Page 10 AlliedWare OS How To Note IGMPExplanation of IGMP snooping processUsing Show command output to investigate IGMP state igmpsnooping on the SnooperNext, 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 When a client leaves a group Page 14 AlliedWare OS How To Note IGMPMultiple potential IGMP queriers Page 15 AlliedWare OS How To Note IGMPExample X Configure switch X Configure switchX Configure switch Page 16 AlliedWare OS How To Note IGMPWhen there are no group members Explanation of Multiple potential IGMP queriersWhen a client joins a group Page 18 AlliedWare OS How To Note IGMPPage 19 AlliedWare OS How To Note IGMP Refresh time 228 secsPage 20 AlliedWare OS How To Note IGMP IGMP proxy Page 21 AlliedWare OS How To Note IGMPExample X Configure switch X Configure switchX Configure switch Switch 3 is an IGMP ProxyWhen a client joins a group Explanation of IGMP proxyWhen there are no group members Page 23 AlliedWare OS How To Note IGMPPage 24 AlliedWare OS How To Note IGMP Refresh time 243 secsWhen a client leaves a group Page 25 AlliedWare OS How To Note IGMPQuery solicitation rapid recovery from topology changes How query solicitation worksQuery Solicit QS Initial stateTC and sends QS and sendsX Configure switch Why convergence takes so long without query solicitationExample X Configure switchExplanation from the perspective of switch 2, the snooper When link comes up again Page 30 AlliedWare OS How To Note IGMPExplanation from the perspective of switch 1, the querier shows this entryagain forwarding the multicast stream out the port Enabling query solicitation on multiple switches in a looped topology Speeding up IGMP convergence in a non-looped topologyto switch from switchSwitch 2 sends QS Switch 1 sends GQIGMP filtering controlling multicast distribution ExampleX Configure switch types commandX Configure switch X Configure switchPage 37 AlliedWare OS How To Note IGMP Passed Explanation of IGMP filtering controlling multicast distributionReceived DroppedPage 39 AlliedWare OS How To Note IGMP IGMP throttling limiting the number of streams for each subscriber ExampleX Configure switch X Configure switchPage 41 AlliedWare OS How To Note IGMP X Configure switch Page 42 AlliedWare OS How To Note IGMPConsider 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 When we deny groups instead of replacing them X Modify switch 2 ConfigurationPage 47 AlliedWare OS How To Note IGMP Static IGMP Page 48 AlliedWare OS How To Note IGMPExample z enable IGMP z enable the interface as an IGMP interface X Configure switchX Configure switch Switch 2 is an IGMP SnooperX Configure switch Page 50 AlliedWare OS How To Note IGMPExplanation of Static IGMP Page 51 AlliedWare OS How To Note IGMPWhen we add a static entry on another switch X Modify switch 3 ConfigurationPage 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 36350 Page 56 AlliedWare OS How To Note IGMPMulticastPkts MulticastPktsWhen a static entry’s port goes down Page 57 AlliedWare OS How To Note IGMPHow clients leave groups queries and timers Querier timer valuesOverview of leave process Snooper timer values Comparing the Querier and Snooper timers Consequences for high-loss and high-lag networksset igmpsnooping fastleave=onoff interface=vlanx IGMP fast leaveExample set igmpsnooping vlan=vlanx fastleave=onoffX Configure switch X Configure switchX Configure switch Page 62 AlliedWare OS How To Note IGMPExplanation of IGMP fast leave Page 63 AlliedWare OS How To Note IGMPWhen fast leave is disabled Page 64 AlliedWare OS How To Note IGMPWhen you enable fast leave on switch It is safe to ignore the group entry on switchWhen you set fast leave on all interfaces Similarly, we can easily disable Fast Leave on all interfacesMultiple host mode for fast leave Page 68 AlliedWare OS How To Note IGMP z Timer and counter relationships on page z Software versions on page Configurable IGMP timers and countersTimer and counter relationships z Initial configuration on page z Default values on pageInitial configuration Software versionsX Configure switch X Configure switchX Configure switch Configurable IGMP timers and counters Initial configurationDefault values Last Member Query Count and Last Member Query IntervalWhat these counters do Last Member Query Interval Potential problems with changing these countersHow to change these counters 1/10secsPage 74 AlliedWare OS How To Note IGMP Last Member Query CountRobustness Variable Potential problems with changing this counterHow to change this counter What this counter doesPotential problems with changing this timer Default Query IntervalWhat this timer does How to change this timerPotential problems with changing this timer Query Response IntervalWhat this timer does How to change this timerWhat this timer does Default Timeout IntervalSynchronisation of timers Potential problems with changing this timerThe Default Timeout Interval = 2*125 + 100/10 = 260 seconds Increase Default Query IntervalDefaults First, the following output shows the default settings Next, change the Default Query Interval to 130 secondsIncrease Query Response Interval Page 80 AlliedWare OS How To Note IGMPOverride Default Timeout Interval Page 81 AlliedWare OS How To Note IGMPDefault Timeout Interval = Default Timeout Interval = 2 * 200 + 10 = 410 secondsPage 82 AlliedWare OS How To Note IGMP Default Timeout Interval Example of bad choices for timer valuesTimer set ip igmp timeout=126Problem 1 Last Member Query Interval too short Problem 2 Query Response Interval shortProblem 3 Default Timeout Interval too short For more information, see Synchronisation of timers on page not recommend thisStopping snoopers from snooping non-IGMP messages ExampleOSPF X Configure switch X Configure switchX Configure switch Page 87 AlliedWare OS How To Note IGMPX Configure the router Page 89 AlliedWare OS How To Note IGMP Ports 25Ports Preventing an All Groups entry for a port Disabling All Groups entry for a portEnabling All Groups entry again 2. Check the group entry timeout values3. Reset port 24’s packet counters 1. Permit port 24 to be an All Groups port again5. Check the group entry timeout values again Page 92 AlliedWare OS How To Note IGMP6. Enable IGMP debugging 8. Check the group entry timeout values againPage 93 AlliedWare OS How To Note IGMP z the streams group entry times out and is refreshed, or z the ports internal timer hits zero and is refreshedPage 94 AlliedWare OS How To Note IGMP It is most likely that the group entry will time out firstControlling 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 Returning to the default list To return to the default list, change the router mode to defaultUsing the other routermode options Page 100 AlliedWare OS How To Note IGMPStatically 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 X Output for show ip igmp changes Page 107 AlliedWare OS How To Note IGMPSwitch Appendix STP stateSwitch Page 109 AlliedWare OS How To Note IGMPSwitch USA Headquarters 19800 North Creek Parkway Suite 100 Bothell WA 98011 USA T +1 800 424 4284 F +1 425 481