Igmp Snooping; Differences Between Regular And Multicast Tv Vlans - Cisco SF500-24 Administration Manual

VLAN Management
Access Port Multicast TV VLAN
Cisco 500 Series Stackable Managed Switch Administration Guide

IGMP Snooping

Multicast TV VLAN relies on IGMP snooping, which means that:
• Subscribers use IGMP messages to join or leave a Multicast group.
• Switch performs IGMP snooping and configures the access port according
to its Multicast membership on Multicast TV VLAN
The switch decides for each IGMP packet that is received on an access port
whether to associate it with the access VLAN or with the Multicast TV VLAN
according to the following rules:
• If an IGMP message is received on an access port, with destination
Multicast IP address that is associated with the port's Multicast TV VLAN,
then the software associates the IGMP packet with the Multicast TV VLAN.
• Otherwise the IGMP message is associated to the access VLAN and the
IGMP message is only forwarded within that VLAN.
• The IGMP message is discarded if:
- The STP/RSTP state on the access port is discard.
- The MSTP state for the access VLAN is discard.
- The MSTP state for the Multicast TV VLAN is discard, and the IGMP
message is associated with this Multicast TV VLAN.

Differences Between Regular and Multicast TV VLANs

Table 7 Characteristics of Regular vs. Multicast TV VLANs
VLAN Membership
Group registration
Regular VLAN
Source and all receiver
ports must be static
members in the same
data VLAN.
All Multicast group
registration is dynamic.
.
Multicast TV VLAN
Source and receiver ports
cannot be members in the
same data VLAN.
Groups must be associated
to Multicast VLAN statically,
but actual registration of
station is dynamic.
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