address of 224.0.0.1, to which all multicast hosts will answer.
subsequent reports for the same group coming from different hosts will be
suppressed. This is done because only one host on a subnet/VLAN needs to
request membership for the router to activate that group on the interface.
Once active on the router interface, any host on that segment wanting to
receive data for that specific group will receive it. Figure 9.8 depicts how this
process works.
host to respond (#2a) is HostB, requesting data for the multicast group
224.2.127.254. HostD responds next (#3a) with a request for the group
224.2.168.242. The next host to reply is HostA (#4a). However, because the
report from HostD was already multicast to the 224.2.168.242 group,
HostA heard the report and suppressed its own report to the group.