System information

Configuring Multicast Forwarding
MLD Snooping
Cisco Small Business 200 Series Smart Switch Administration Guide 137
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In an approach similar to IGMP snooping, MLD frames are snooped as they are
forwarded by the switch from stations to an upstream Multicast router and vice
versa. This facility enables a switch to conclude the following:
• On which ports stations interested in joining a specific Multicast group are
located
• On which ports Multicast routers sending Multicast frames are located
This knowledge is used to exclude irrelevant ports (ports on which no stations
have registered to receive a specific Multicast group) from the forwarding set of
an incoming Multicast frame.
If you enable MLD snooping in addition to the manually-configured Multicast
groups, the result is a union of the Multicast groups and port memberships derived
from the manual setup and the dynamic discovery by MLD snooping. However,
only the static definitions are preserved when the system is rebooted.
To e n a b l e M L D S n o o p i n g :
STEP 1 Click Multicast > MLD Snooping. The MLD Snooping Page opens.
STEP 2 Enable or disable MLD Snooping Status. MLD Snooping Status globally enables
the device monitoring network traffic to determine which hosts have requested to
receive Multicast traffic. The switch performs MLD Snooping if MLD snooping and
Bridge Multicast filtering are both enabled.
The MLD Snooping Table block lists the operational MLD snooping information for
the VLANs on the switch. For a description of the table columns, see STEP 3.
STEP 3 Select a VLAN, and click Edit. The Edit MLD Snooping Page opens.
STEP 4 Enter the parameters.
• VLAN ID—Select the VLAN ID.
• MLD Snooping Status—Enable or disable MLD snooping on the VLAN. The
switch monitors network traffic to determine which hosts have asked to be
sent Multicast traffic. The switch performs MLD snooping only when MLD
snooping and Bridge Multicast filtering are both enabled.
• Operational MLD Snooping Status—Displays the current status of MLD
Snooping for the selected VLAN.
• MRouter Ports Auto-Learn—Enable or disable Auto Learn for the Multicast
router.