26
CONFIDENTIAL
26-Jan-04
© 2002 Procket Networks, Inc. All rights reserved.
IGMP Details
•Router:
•sends Membership Query messages to All Hosts (224.0.0.1)
•query-interval = 125 secs default
•router with lowest IP address is Querier (rest non-queriers)
•If lower-IP address query heard, backoff to non-querier state
•Other Querier Present Interval default: (robust-count x query-interval) + (0.5 x query-response-interval) = 255 secs
•listens for reports (whether querier or not) and adds group to membership list for that interface
•query-response-interval = 10 secs default
•timeout (Group member interval) default:
•(robust-count x query-interval) + (1 x query-response-interval) =   260 sec
•robust-count - provides fine-tuning to allow for expected packet loss on a subnet. Default = 2 (tunable from 2-10)
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