Allied Telesis AR400 manual Configurable Igmp timers and counters, Timer and counter relationships

Page 69

Configurable IGMP timers and counters > Timer and counter relationships

Configurable IGMP timers and counters

This section looks at some of the timers and counters that control how often IGMP sends queries and how quickly entries time out. First, it gives background information in the following subsections:

z"Timer and counter relationships" on page 69

z"Software versions" on page 70

z"Initial configuration" on page 70

z"Default values" on page 72

Then it looks at each of the configurable timers and counters, in the following subsections:

z"Last Member Query Count and Last Member Query Interval" on page 72

z"Robustness Variable" on page 75

z"Default Query Interval" on page 76

z"Query Response Interval" on page 77

z"Default Timeout Interval" on page 78 (the Group Membership Interval of RFC 2236)

RFC 2236 also describes other counters and timers that this section does not describe, because this section only describes the counters and timers that you can directly set. The router or switch derives other counters and timers from the above subset.

Timer and counter relationships

The above timers and counters are related to each other and to others in RFC 2236 by the following formulae:

zLast Member Query Count = Robustness Variable

zDefault Timeout Interval = (Robustness Variable * Default Query Interval) + one Query Response Interval in seconds

zStartup Query Count = Robustness Variable

The Startup Query Count is the number of General Queries that the Querier sends when it starts up.

zOther Querier Timeout = (Robustness Variable * Default Query Interval) + (Query Response Interval in seconds/2)

The Other Querier Timeout is the length of time that a potential Querier waits after receiving a Query before it assumes that it should become the Querier.

These relationships mean you need to take care if you change timers or counters. "Example of bad choices for timer values" on page 83 describes the consequences of a bad combination of values.

Page 69 AlliedWare™ OS How To Note: IGMP

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Contents Introduction ContentsHow clients leave groups queries and timers Query solicitation rapid recovery from topology changesConfigurable Igmp timers and counters Example of bad choices for timer valuesProducts and software versions this note applies to 4 AlliedWare OS How To Note Igmp Igmp feature Software versions Products5 AlliedWare OS How To Note Igmp Igmp overviewQueriers and Snoopers Messages 6 AlliedWare OS How To Note IgmpChoosing group addresses 7 AlliedWare OS How To Note IgmpIP address, binary MAC address, hexAvoid x.0.0.y, x.0.1.y, x.128.0.y, and x.128.1.y 8 AlliedWare OS How To Note Igmp9 AlliedWare OS How To Note Igmp Igmp snoopingExample 10 AlliedWare OS How To Note Igmp Configure switchExplanation of Igmp snooping 11 AlliedWare OS How To Note IgmpGroup List Entry timeout 136 secs Ports None Using Show command output to investigate Igmp stateGroup List Entry timeout 257 Secs Ports All Groups 235 12 AlliedWare OS How To Note IgmpGroup Last Adv 13 AlliedWare OS How To Note IgmpWhen a client leaves a group Group List Entry timeout 247 secs Ports14 AlliedWare OS How To Note Igmp Multiple potential Igmp queriers 15 AlliedWare OS How To Note Igmp16 AlliedWare OS How To Note Igmp When there are no group members Other Querier timeout .. secs17 AlliedWare OS How To Note Igmp Group List Entry timeout 225 secs Ports When a client joins a groupAll Groups Entry timeout Secs Ports 18 AlliedWare OS How To Note Igmp19 AlliedWare OS How To Note Igmp Group ListGroup List Last Adv 20 AlliedWare OS How To Note Igmp Igmp proxy 21 AlliedWare OS How To Note Igmp22 AlliedWare OS How To Note Igmp Switch 3 is an Igmp ProxyAll Groups Entry timeout 145 Secs Ports Group List Entry timeout 122 secs Ports None23 AlliedWare OS How To Note Igmp Explanation of Igmp proxy24 AlliedWare OS How To Note Igmp Group Entry timeout Secs Ports25 AlliedWare OS How To Note Igmp Group Entry timeout 182 secs PortsQuery solicitation rapid recovery from topology changes 26 AlliedWare OS How To Note IgmpHow query solicitation works Initial state 27 AlliedWare OS How To Note IgmpWhy convergence takes so long without query solicitation 28 AlliedWare OS How To Note IgmpExample 29 AlliedWare OS How To Note Igmp Explanation from the perspective of switch 2, the snooper30 AlliedWare OS How To Note Igmp All Groups Entry timeout 236 secs PortsGroup Entry timeout 18 secs Ports Explanation from the perspective of switch 1, the querier31 AlliedWare OS How To Note Igmp Shows this entry32 AlliedWare OS How To Note Igmp Group Entry timeout 115 secs PortsSpeeding up Igmp convergence in a non-looped topology 33 AlliedWare OS How To Note IgmpSwitch 1 sends GQ 34 AlliedWare OS How To Note IgmpIgmp filtering controlling multicast distribution 35 AlliedWare OS How To Note IgmpTypes command Set switch port=1 igmpfilter=136 AlliedWare OS How To Note Igmp 37 AlliedWare OS How To Note Igmp Switch 3 is also an Igmp SnooperReceived Passed Dropped 38 AlliedWare OS How To Note IgmpNo group memberships 39 AlliedWare OS How To Note Igmp40 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 When we deny groups instead of replacing them Modify switch 2 Configuration46 AlliedWare OS How To Note Igmp 47 AlliedWare OS How To Note Igmp Group 224.12.13.11 Entry timeout 255 secs Ports 224.12.13.12Static Igmp 48 AlliedWare OS How To Note Igmp49 AlliedWare OS How To Note Igmp Switch 2 is an Igmp Snooper50 AlliedWare OS How To Note Igmp Group Entry timeout Infinity Ports 51 AlliedWare OS How To Note IgmpExplanation of Static Igmp Modify switch 3 Configuration When we add a static entry on another switch52 AlliedWare OS How To Note Igmp MulticastPkts 67582653 AlliedWare OS How To Note Igmp All Groups Entry timeout 247 secs Ports54 AlliedWare OS How To Note Igmp 55 AlliedWare OS How To Note Igmp Group Entry timeout Infinity Ports 5,2656 AlliedWare OS How To Note Igmp MulticastPkts 36350MulticastPkts 14756 When a static entry’s port goes down Group Entry timeout Infinity Ports None57 AlliedWare OS How To Note Igmp Querier timer values How clients leave groups queries and timers58 AlliedWare OS How To Note Igmp Overview of leave process59 AlliedWare OS How To Note Igmp Snooper timer values60 AlliedWare OS How To Note Igmp Comparing the Querier and Snooper timersConsequences for high-loss and high-lag networks Describes the new behaviourIgmp fast leave 61 AlliedWare OS How To Note Igmp62 AlliedWare OS How To Note Igmp Switch 1 is an Igmp QuerierExplanation of Igmp fast leave 63 AlliedWare OS How To Note IgmpGroup Entry timeout 2 secs Ports When fast leave is disabled64 AlliedWare OS How To Note Igmp Fast Leave OffIt is safe to ignore the group entry on switch When you enable fast leave on switchGroup Entry timeout Secs Ports None 65 AlliedWare OS How To Note Igmp66 AlliedWare OS How To Note Igmp When you set fast leave on all interfacesTo specify multiple mode, use the command Multiple host mode for fast leaveTo specify single mode, use either of the commands 67 AlliedWare OS How To Note Igmp68 AlliedWare OS How To Note Igmp Configurable Igmp timers and counters Timer and counter relationships69 AlliedWare OS How To Note Igmp Each example modifies the following base configuration Initial configuration70 AlliedWare OS How To Note Igmp Software versions71 AlliedWare OS How To Note Igmp 72 AlliedWare OS How To Note Igmp Default valuesLast Member Query Count and Last Member Query Interval What these counters doHow to change these counters Potential problems with changing these counters73 AlliedWare OS How To Note Igmp Last Member Query Interval 255 10secsLast Member Query Count 74 AlliedWare OS How To Note IgmpHow to change this counter Potential problems with changing this counterRobustness Variable What this counter doesWhat this timer does Default Query IntervalPotential problems with changing this timer How to change this timer77 AlliedWare OS How To Note Igmp Query Response IntervalQuery Response Interval 100 10secs Default Timeout Interval Synchronisation of timers78 AlliedWare OS How To Note Igmp 79 AlliedWare OS How To Note Igmp Default Timeout Interval = 2*130 + 100/10 = 270 secondsDefault Timeout Interval 280 Secs Default Timeout Interval = 2*125 + 100/10 = 260 seconds80 AlliedWare OS How To Note Igmp Query Response Interval 200 10secs81 AlliedWare OS How To Note Igmp Default Timeout Interval 180 Secs82 AlliedWare OS How To Note Igmp Default Query Interval 200 Secs Default Timeout Interval 410Imagine the following changes to the configuration Example of bad choices for timer valuesCommands to configure these settings are 83 AlliedWare OS How To Note IgmpProblem 2 Query Response Interval short Problem 1 Last Member Query Interval too shortProblem 3 Default Timeout Interval too short Last Member Query Interval was set to 5, using the command85 AlliedWare OS How To Note Igmp For more information, see Synchronisation of timers onStopping snoopers from snooping non-IGMP messages 86 AlliedWare OS How To Note Igmp87 AlliedWare OS How To Note Igmp 88 AlliedWare OS How To Note Igmp Configure the routerRouter uses Ospf Ports 24Ports 25 89 AlliedWare OS How To Note Igmp90 AlliedWare OS How To Note Igmp Disabled All-groups PortsPreventing an All Groups entry for a port Disabling All Groups entry for a portReset port 24’s packet counters Check the group entry timeout valuesEntry timeout 216 Secs Enabling All Groups entry againEntry timeout Secs Check the group entry timeout values again92 AlliedWare OS How To Note Igmp MulticastPktsEnable Igmp debugging Entry timeout 259 Secs93 AlliedWare OS How To Note Igmp MulticastPkts 914 94 AlliedWare OS How To Note IgmpControlling which addresses create All Groups entries 95 AlliedWare OS How To Note IgmpConfiguring switch 96 AlliedWare OS How To Note Igmp224.0.0.5 97 AlliedWare OS How To Note Igmp Configuring switches 1 98 AlliedWare OS How To Note IgmpAdding other router addresses Returning to the default list 99 AlliedWare OS How To Note Igmp224.0.0.254 100 AlliedWare OS How To Note Igmp Using the other routermode options101 AlliedWare OS How To Note Igmp Statically specifying that a port is a router portCheck the current Igmp snooping entries 102 AlliedWare OS How To Note Igmp To remove the static configuration, simply delete itStatically add port 6 as a router port attached to Vlan Stop port 6 from being a static router port103 AlliedWare OS How To Note Igmp Igmp debuggingClient joins a group 104 AlliedWare OS How To Note Igmp IgmpSnoopMembershipQuery setting timer at 2 secs for groupClient leaves a group Several minutes later the group entry times out105 AlliedWare OS How To Note Igmp Manager Switch 3 del vlan=100 port=5Port entry times out Snooped ports change106 AlliedWare OS How To Note Igmp Report is filtered outPort in the All Groups list is unplugged Output for show ip igmp changes 107 AlliedWare OS How To Note Igmp108 AlliedWare OS How To Note Igmp SwitchAppendix STP state State Forwarding109 AlliedWare OS How To Note Igmp Manager Switch 3 show stp port=25-26