Cisco Catalyst 2960 Series, Configuration Manual

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The following is an example configuration.
Figure 6: Multicast VLAN Registration Example
In this example configuration, DHCP assigns an IP address to the set-top box or the PC. When a subscriber
selects a channel, the set-top box or PC sends an IGMP report to Switch A to join the appropriate multicast.
If the IGMP report matches one of the configured IP multicast group addresses, the switch CPU modifies the
hardware address table to include this receiver port and VLAN as a forwarding destination of the specified
multicast stream when it is received from the multicast VLAN. Uplink ports that send and receive multicast
data to and from the multicast VLAN are called MVR source ports.
When a subscriber changes channels or turns off the television, the set-top box sends an IGMP leave message
for the multicast stream. The switch CPU sends a MAC-based general query through the receiver port VLAN.
If there is another set-top box in the VLAN still subscribing to this group, that set-top box must respond within
the maximum response time specified in the query. If the CPU does not receive a response, it eliminates the
receiver port as a forwarding destination for this group.
Without Immediate Leave, when the switch receives an IGMP leave message from a subscriber on a receiver
port, it sends out an IGMP query on that port and waits for IGMP group membership reports. If no reports
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Information About IGMP Snooping and MVR