60
Figure 22 Sub-VLAN-based multicast VLAN
IGMP snooping manages router ports in the multicast VLAN and member ports in the sub-VLANs.
When Router A receives the multicast data from the source, it sends only one copy of the multicast
data to Switch A in the multicast VLAN. Switch A distributes a separate copy of the data to each
sub-VLAN of the multicast VLAN.
Port-based multicast VLAN
As shown in
,:
•
Host A, Host B, and Host C are in VLAN 2 through VLAN 4, respectively.
•
On Switch A, VLAN 10 is configured as a multicast VLAN.
All user ports (ports with attached hosts) are hybrid ports and are assigned to VLAN 10.
IGMP snooping is enabled for the multicast VLAN and VLAN 2 through VLAN 4.
Figure 23 Port-based multicast VLAN
IGMP snooping manages the router ports and member ports in the multicast VLAN. When Switch A
receives an IGMP message on a user port, it tags the message with the multicast VLAN ID and
sends it to the IGMP querier. When Router A receives the multicast data, it sends only one copy of
Source
VLAN 2
VLAN 3
VLAN 4
GE1/0/1
GE1/0/2
GE1/0/3
GE1/0/4
Switch A
Multicast packets
Receiver
Host A
Receiver
Host B
Receiver
Host C
Router A
IGMP querier
VLAN 10 (Multicast VLAN)
