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The possibility exists, however, that this initial report
message will not reach the router. The host should make a transition
from the Non-Member state to the Delaying Member state, as though
the host had received a Host Membership Query message. The host then
starts the delay timer. If a Host Membership Report is received, the
host stops the timer and makes a transition to the Idle Member
state. If the timer expires, the host sends a Host Membership Report
message to the router and then moves to the idle state. When a Host
Membership query is received, the host could be in any of the three
states. In the Non-Member state, the host simply ignores the
message. In the idle state, the host will make a transition to the
delaying state and start the report delay timer. If the report is
received while the host is in the delaying state, the host does not
reset the timer but continues to delay with the current timer value.
Finally, when a host decides to leave the group, it does so silently
because there is not a leave group message in IGMP version 1. If the
host is the last host to leave the group, the router does not know
this until there has been no response to the router’s periodic Host
Membership Query messages. |
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