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MLD Snooping
Cisco Small Business 300 Series Managed Switch Administration Guide 248
15
In an approach similar to IGMP snooping, MLD frames are snooped as they are
forwarded by the device from stations to an upstream Multicast router and vice
versa. This facility enables a device 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. Only 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.
STEP 2 Enable or disable MLD Snooping Status. When MLD Snooping is globally
enabled, the device monitoring network traffic can determine which hosts have
requested to receive Multicast traffic. The device performs MLD Snooping only if
both MLD snooping and Bridge Multicast filtering are enabled.
STEP 3 Select a VLAN, and click Edit.
STEP 4 Enter the parameters.
• VLAN ID—Select the VLAN ID.
• MLD Snooping Status—Enable or disable MLD snooping on the VLAN. The
device monitors network traffic to determine which hosts have asked to be
sent Multicast traffic. The device 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.
• Query Robustness—Enter the Robustness Variable value to be used if the
device cannot read this value from messages sent by the elected querier.