Chapter 16
| Multicast Filtering
MLD Snooping (Snooping and Query for IPv6)
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MLD Snooping (Snooping and Query for IPv6)
Multicast Listener Discovery (MLD) snooping operates on IPv6 traffic and performs
a similar function to IGMP snooping for IPv4. That is, MLD snooping dynamically
configures switch ports to limit IPv6 multicast traffic so that it is forwarded only to
ports with users that want to receive it. This reduces the flooding of IPv6 multicast
packets in the specified VLANs.
There are two versions of the MLD protocol, version 1 and version 2. MLDv1 control
packets include Listener Query, Listener Report, and Listener Done messages
(equivalent to IGMPv2 query, report, and leave messages). MLDv2 control packets
include MLDv2 query and report messages, as well as MLDv1 report and done
messages.
Remember that IGMP Snooping and MLD Snooping are independent functions,
and can therefore both function at the same time.
Configuring MLD
Snooping and Query
Parameters
Use the Multicast > MLD Snooping > General page to configure the switch to
forward multicast traffic intelligently. Based on the MLD query and report
messages, the switch forwards multicast traffic only to the ports that request it. This
prevents the switch from broadcasting the traffic to all ports and possibly
disrupting network performance.
Parameters
These parameters are displayed:
◆ MLD Snooping Status – When enabled, the switch will monitor network traffic
to determine which hosts want to receive multicast traffic. (Default: Disabled)
◆ Querier Status – When enabled, the switch can serve as the querier for MLDv2
snooping if elected. The querier is responsible for asking hosts if they want to
receive multicast traffic. (Default: Disabled)
An IPv6 address must be configured on the VLAN interface from which the
querier will act if elected. When serving as the querier, the switch uses this IPv6
address as the query source address.
The querier will not start or will disable itself after having started if it detects an
IPv6 multicast router on the network.
◆ Robustness – MLD Snooping robustness variable. A port will be removed from
the receiver list for a multicast service when no MLD reports are detected in
response to a number of MLD queries. The robustness variable sets the number
of queries on ports for which there is no report. (Range: 2-10 Default: 2)
◆ Query Interval – The interval between sending MLD general queries.
(Range: 60-125 seconds; Default: 125 seconds)
This attribute applies when the switch is serving as the querier.
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