Example, AlliedWare OS How To Note Igmp | Allied Telesis AR400

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

Why convergence takes so long without query solicitation

This section illustrates IGMP convergence in a simple network that does not need STP because it has no switch loops. Query Solicitation is disabled by default in networks like this, because no switch is an STP root bridge or an EPSR master node.

In this network, it takes up to 125 seconds for multicasting to recover after a port comes back up. This section explains the reason for the slow convergence. "Speeding up IGMP convergence in a non-looped topology" on page 33 explains the solution.

Example

The following figure shows the network for the example in this section.

		Multicast Server
			Client 1
		port 24	port 9
	Switch 1:	port 1	port 1	Switch 2:
	Querier	port 1	port 1	Snooper
	Querier	Rapier 24i	Rapier 24i	Snooper
				igmp-no-qs.eps

The example considers what happens when a port comes up. When the port was down, the client stopped receiving multicasts, because there was no backup route available. The example shows how the network recovers. The multicast group is 224.12.13.14.

XConfigure switch 1

Switch 1 is configured with IGMP, which makes it the IGMP Querier in this network.

set system name="Switch 1"

#IP configuration enable ip

add ip int=vlan1 ip=10.13.2.191 mask=255.255.255.0 enable ip igmp

enable ip igmp int=vlan1

XConfigure switch 2

Switch 2 is an IGMP Snooper. It forwards multicast packets and IGMP messages as required. IGMP snooping is enabled by default and does not need any configuration.

set system name="Switch 2"

#IP configuration enable ip

add ip int=vlan1 ip=10.13.2.193 mask=255.255.255.0

Page 28 AlliedWare™ OS How To Note: IGMP

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Allied Telesis AR400 Why convergence takes so long without query solicitation, Example, AlliedWare OS How To Note Igmp

Contents

Contents Introduction Query solicitation rapid recovery from topology changes How clients leave groups queries and timersConfigurable Igmp timers and counters Example of bad choices for timer values Products and software versions this note applies to Igmp feature Software versions Products 4 AlliedWare OS How To Note Igmp Igmp overview 5 AlliedWare OS How To Note IgmpQueriers and Snoopers 6 AlliedWare OS How To Note Igmp Messages 7 AlliedWare OS How To Note Igmp Choosing group addressesIP address, binary MAC address, hex 8 AlliedWare OS How To Note Igmp Avoid x.0.0.y, x.0.1.y, x.128.0.y, and x.128.1.y Igmp snooping 9 AlliedWare OS How To Note IgmpExample Configure switch 10 AlliedWare OS How To Note Igmp 11 AlliedWare OS How To Note Igmp Explanation of Igmp snooping Using Show command output to investigate Igmp state Group List Entry timeout 136 secs Ports NoneGroup List Entry timeout 257 Secs Ports All Groups 235 12 AlliedWare OS How To Note Igmp 13 AlliedWare OS How To Note Igmp Group Last Adv Group List Entry timeout 247 secs Ports When a client leaves a group14 AlliedWare OS How To Note Igmp 15 AlliedWare OS How To Note Igmp Multiple potential Igmp queriers 16 AlliedWare OS How To Note Igmp Other Querier timeout .. secs When there are no group members17 AlliedWare OS How To Note Igmp When a client joins a group Group List Entry timeout 225 secs PortsAll Groups Entry timeout Secs Ports 18 AlliedWare OS How To Note Igmp Group List 19 AlliedWare OS How To Note IgmpGroup List Last Adv 20 AlliedWare OS How To Note Igmp 21 AlliedWare OS How To Note Igmp Igmp proxy Switch 3 is an Igmp Proxy 22 AlliedWare OS How To Note Igmp Group List Entry timeout 122 secs Ports None All Groups Entry timeout 145 Secs Ports23 AlliedWare OS How To Note Igmp Explanation of Igmp proxy Group Entry timeout Secs Ports 24 AlliedWare OS How To Note Igmp Group Entry timeout 182 secs Ports 25 AlliedWare OS How To Note Igmp 26 AlliedWare OS How To Note Igmp Query solicitation rapid recovery from topology changesHow query solicitation works 27 AlliedWare OS How To Note Igmp Initial state 28 AlliedWare OS How To Note Igmp Why convergence takes so long without query solicitationExample Explanation from the perspective of switch 2, the snooper 29 AlliedWare OS How To Note Igmp All Groups Entry timeout 236 secs Ports 30 AlliedWare OS How To Note Igmp Explanation from the perspective of switch 1, the querier Group Entry timeout 18 secs Ports31 AlliedWare OS How To Note Igmp Shows this entry Group Entry timeout 115 secs Ports 32 AlliedWare OS How To Note Igmp 33 AlliedWare OS How To Note Igmp Speeding up Igmp convergence in a non-looped topology 34 AlliedWare OS How To Note Igmp Switch 1 sends GQ 35 AlliedWare OS How To Note Igmp Igmp filtering controlling multicast distribution Set switch port=1 igmpfilter=1 Types command36 AlliedWare OS How To Note Igmp Switch 3 is also an Igmp Snooper 37 AlliedWare OS How To Note Igmp 38 AlliedWare OS How To Note Igmp Received Passed Dropped 39 AlliedWare OS How To Note Igmp No group memberships 40 AlliedWare OS How To Note Igmp 41 AlliedWare OS How To Note Igmp 42 AlliedWare OS How To Note Igmp 43 AlliedWare OS How To Note Igmp 44 AlliedWare OS How To Note Igmp 45 AlliedWare OS How To Note Igmp Modify switch 2 Configuration When we deny groups instead of replacing them46 AlliedWare OS How To Note Igmp Group 224.12.13.11 Entry timeout 255 secs Ports 224.12.13.12 47 AlliedWare OS How To Note Igmp 48 AlliedWare OS How To Note Igmp Static Igmp Switch 2 is an Igmp Snooper 49 AlliedWare OS How To Note Igmp 50 AlliedWare OS How To Note Igmp 51 AlliedWare OS How To Note Igmp Group Entry timeout Infinity PortsExplanation of Static Igmp When we add a static entry on another switch Modify switch 3 Configuration52 AlliedWare OS How To Note Igmp MulticastPkts 675826 All Groups Entry timeout 247 secs Ports 53 AlliedWare OS How To Note Igmp 54 AlliedWare OS How To Note Igmp Group Entry timeout Infinity Ports 5,26 55 AlliedWare OS How To Note Igmp MulticastPkts 36350 56 AlliedWare OS How To Note IgmpMulticastPkts 14756 Group Entry timeout Infinity Ports None When a static entry’s port goes down57 AlliedWare OS How To Note Igmp How clients leave groups queries and timers Querier timer values58 AlliedWare OS How To Note Igmp Overview of leave process Snooper timer values 59 AlliedWare OS How To Note Igmp Comparing the Querier and Snooper timers 60 AlliedWare OS How To Note IgmpConsequences for high-loss and high-lag networks Describes the new behaviour 61 AlliedWare OS How To Note Igmp Igmp fast leave Switch 1 is an Igmp Querier 62 AlliedWare OS How To Note Igmp 63 AlliedWare OS How To Note Igmp Explanation of Igmp fast leave When fast leave is disabled Group Entry timeout 2 secs Ports64 AlliedWare OS How To Note Igmp Fast Leave Off When you enable fast leave on switch It is safe to ignore the group entry on switchGroup Entry timeout Secs Ports None 65 AlliedWare OS How To Note Igmp When you set fast leave on all interfaces 66 AlliedWare OS How To Note Igmp Multiple host mode for fast leave To specify multiple mode, use the commandTo specify single mode, use either of the commands 67 AlliedWare OS How To Note Igmp 68 AlliedWare OS How To Note Igmp Timer and counter relationships Configurable Igmp timers and counters69 AlliedWare OS How To Note Igmp Initial configuration Each example modifies the following base configuration70 AlliedWare OS How To Note Igmp Software versions 71 AlliedWare OS How To Note Igmp Default values 72 AlliedWare OS How To Note IgmpLast Member Query Count and Last Member Query Interval What these counters do Potential problems with changing these counters How to change these counters73 AlliedWare OS How To Note Igmp Last Member Query Interval 255 10secs 74 AlliedWare OS How To Note Igmp Last Member Query Count Potential problems with changing this counter How to change this counterRobustness Variable What this counter does Default Query Interval What this timer doesPotential problems with changing this timer How to change this timer Query Response Interval 77 AlliedWare OS How To Note IgmpQuery Response Interval 100 10secs Synchronisation of timers Default Timeout Interval78 AlliedWare OS How To Note Igmp Default Timeout Interval = 2*130 + 100/10 = 270 seconds 79 AlliedWare OS How To Note Igmp Default Timeout Interval = 2*125 + 100/10 = 260 seconds Default Timeout Interval 280 Secs80 AlliedWare OS How To Note Igmp Query Response Interval 200 10secs Default Timeout Interval 180 Secs 81 AlliedWare OS How To Note Igmp Default Query Interval 200 Secs Default Timeout Interval 410 82 AlliedWare OS How To Note Igmp Example of bad choices for timer values Imagine the following changes to the configurationCommands to configure these settings are 83 AlliedWare OS How To Note Igmp Problem 1 Last Member Query Interval too short Problem 2 Query Response Interval shortProblem 3 Default Timeout Interval too short Last Member Query Interval was set to 5, using the command For more information, see Synchronisation of timers on 85 AlliedWare OS How To Note Igmp 86 AlliedWare OS How To Note Igmp Stopping snoopers from snooping non-IGMP messages 87 AlliedWare OS How To Note Igmp Configure the router 88 AlliedWare OS How To Note IgmpRouter uses Ospf Ports 24 89 AlliedWare OS How To Note Igmp Ports 25 Disabled All-groups Ports 90 AlliedWare OS How To Note IgmpPreventing an All Groups entry for a port Disabling All Groups entry for a port Check the group entry timeout values Reset port 24’s packet countersEntry timeout 216 Secs Enabling All Groups entry again Check the group entry timeout values again Entry timeout Secs92 AlliedWare OS How To Note Igmp MulticastPkts Entry timeout 259 Secs Enable Igmp debugging93 AlliedWare OS How To Note Igmp 94 AlliedWare OS How To Note Igmp MulticastPkts 914 95 AlliedWare OS How To Note Igmp Controlling which addresses create All Groups entries 96 AlliedWare OS How To Note Igmp Configuring switch224.0.0.5 97 AlliedWare OS How To Note Igmp 98 AlliedWare OS How To Note Igmp Configuring switches 1Adding other router addresses 99 AlliedWare OS How To Note Igmp Returning to the default list224.0.0.254 Using the other routermode options 100 AlliedWare OS How To Note Igmp Statically specifying that a port is a router port 101 AlliedWare OS How To Note IgmpCheck the current Igmp snooping entries To remove the static configuration, simply delete it 102 AlliedWare OS How To Note IgmpStatically add port 6 as a router port attached to Vlan Stop port 6 from being a static router port Igmp debugging 103 AlliedWare OS How To Note IgmpClient joins a group IgmpSnoopMembershipQuery setting timer at 2 secs for group 104 AlliedWare OS How To Note IgmpClient leaves a group Several minutes later the group entry times out Manager Switch 3 del vlan=100 port=5 105 AlliedWare OS How To Note IgmpPort entry times out Snooped ports change Report is filtered out 106 AlliedWare OS How To Note IgmpPort in the All Groups list is unplugged 107 AlliedWare OS How To Note Igmp Output for show ip igmp changes Switch 108 AlliedWare OS How To Note IgmpAppendix STP state State Forwarding 109 AlliedWare OS How To Note Igmp Manager Switch 3 show stp port=25-26