OK, so I am finally studying multicast routing! (...waits for applause to die down...)
I suppose IGMPv2 is more widespread today than IGMPv1 but I'm told they'll BOTH be on the BSCI exam (grumble...)
If I understand this right, under IGMPv1, a host that wants to join a mcast group sends a "membership report" to the IGMPv1 Querier. The Querier also queries everyone every 60sec if they want to remain in the multicast group; and if they don't reply to 3 consecutive queries, they're axed from the group.
Question: If the client device has to send a membership report every 60 sec, what's the purpose of having one router continually query it?
It seems uneconomical for the querier to have to send out a packet every 60 sec just to solicit something equally simple as a hello packet; when you could instead just have the client devices send their membership reports pro-actively and lose the "query" traffic.