What are the differences between IGMP version 1 and 2 (v1 and v2) ?
The biggest operational difference is a that IGMP v2 has an explicit Leave Group message, while in IGMP v1 it is necessary to time out to leave a group. IGMP v2 leave latencies are a few seconds or less, while v1 latencies can be 5 minutes, which can be a real problem if an unwanted multicast transmission is a substantial portion of the total available bandwidth.