I struggle to understand why using static igmp will stop R1 to respond to ICMP echo request from 220.127.116.11. Any idea?
‘ip igmp static-group’ causes the router to fast-switch multicast packets out that interface for the configured group; regardless of IGMP join messages from downstream devices. The router doesn’t join the multicast group so it won’t respond to ICMP messages to it.‘ip igmp join-group’ causes the router to actually join the configured multicast group. http://www.cisco.com/en/US/docs/ios/12_3/ipmulti/command/reference/ip3_i1g.html#wp1133446