Multicast Filtering
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Instruction Manual - NXA-ENET8-POE+
MLD Snooping (Snooping and Query for IPv4)
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.
The following table lists the options on this page:
Multicast - MLD Snooping (General) Options
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.
An MLD general query message is sent by the switch at the interval specified by this attribute.
When this message is received by downstream hosts, all receivers build an MLD report for the
multicast groups they have joined.
Query Max Response Time
The maximum response time advertised in MLD general queries. (Range: 5-25 seconds; Default: 10
seconds)
This attribute controls how long the host has to respond to an MLD Query message before the
switch deletes the group if it is the last member.
Router Port Expiry Time
The time the switch waits after the previous querier stops before it considers the router port (i.e.,
the interface that had been receiving query packets) to have expired. (Range: 300-500 seconds;
Default: 300 seconds)
MLD Snooping Version
The protocol version used for compatibility with other devices on the network. This is the MLD
version the switch uses to send snooping reports. (Range: 1-2; Default: 2)
Unknown Multicast Mode
The action for dealing with unknown multicast packets. Options include:
• Flood - Floods any received IPv6 multicast packets that have not been requested by a host to all
ports in the VLAN.
• To Router Port - Forwards any received IPv6 multicast packets that have not been requested by
a host to ports that are connected to a detected multicast router. (This is the default action.)