IGMP version 1 how hosts stop receiving multicast traffic
In IGMP version 1, there is no "leave group" message as there is in v2 and v3.
A multicast router will periodically send a membership query to destination 224.0.0.1 (all hosts multicast group address). Hosts that receive this message will respond with a membership report to tell the router that they are still interested in receiving the multicast traffic. When the router receives the membership report, it’s expiry timer will be refreshed.
As long as the router receives at least one response to a membership query for a particular multicast group, the router will continue to forward that multicast group. If no hosts respond within the time period of the expiry timer, the router knows that nobody is interested anymore in the multicast traffic and it will then remove the entry once the timer expires.
Typically, the default value of the expiration timer is 260 seconds.
Links:
https://forum.networklessons.com/t/igmp-version-1/1319/36?u=lagapidis