Figure 23 Igmp Snooping Application; Multicast Group Join; Multicast Group Leave - Zte ZXR10 5900E Series User Manual

ZXR10 5900E Series User Manual (Ethernet Switching Volume)
F 23 IGMP SNOOPING APPLICATION
IGURE

Multicast Group Join

The host joins corresponding multicast group by sending an IGMP
joining message. When the switch receives the IGMP host report
from a host for a particular multicast group, the switch adds the
port number of the host to the associated multicast table entry.
When other hosts in the same VLAN are interested in the multicast
traffic and send a membership report, the switch adds them to the
existed forwarding entries.
Switch creates only one forwarding entry for each multicast group
in the same VLAN, forwards the multicast traffic of the multicast
group in all ports receiving the membership report.

Multicast Group Leave

Hosts that joined multicast group must respond to IGMP query
message transmitted by router periodically. As long as one host
responds to IGMP query in a VLAN, the router must continue for-
warding traffic of the multicast group that the host joined to the
VLAN.
When a host wants to leave a multicast group, it could ignore
the IGMP query message transmitted by router periodically (called
"leave quietly"), or send IGMPv2 leave message of specific group.
When IGMP Snooping hears IGMPv2 leave message of specific
group, the switch sends specific group query message to the port
receiving the message to query whether other hosts belonging to
the multicast group are available in this port. If IGMP Snooping
cannot receive any response message after several queries, it in-
dicates that there are no hosts belonging to the multicast group
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