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6.2.3
Multicast Listener Discovery (MLD) Snooping for IPv6
Multicast Listener Discovery Snooping is an IPv6 multicast constraining mechanism that runs
on layer 2 switches to manage and control IPv6 multicast groups. With MLDS, IPv6 multicast
data is selectively forwarded to a list of ports that want to receive the data, instead of being
flooded to all ports in a VLAN. This list is constructed by snooping IPv6 multicast control packets.
In general, significant bandwidth can be wasted by flooding.
Functionality
Presently our layer 2 switches support IGMP Snooping in IPV4. IGMP snooping to limit the
flooding of multicast traffic by dynamically configuring Layer 2 interfaces so that multicast
traffic is forwarded to only those interfaces associated with IP multicast devices.
The functionality of IGMP Snooping in IPv4 version is same as MLD Snooping in IPv6 version.
MLDS supports two versions:
MLDv1 snooping detects MLDv1 control packets and sets up traffic bridging based on IPv6
destination multicast addresses.
MLDv2 basic snooping uses MLDv2 control packets to set up traffic forwarding based on
IPv6 destination multicast addresses.
Proxy Reporting:
All the hosts send their complete multicast group membership information to the multicast router
in response to queries. The switch snoop these responses, updates the database and forwards the
reports to the multicast router. To prevent the multicast router from becoming overloaded with
reports, MLD snooping does proxy reporting. Proxy reporting forwards only the first report for
a multicast group to the router and suppresses all other reports for the same multicast group.
Report-Suppression-Interval:
Only one report is forwarded within the report forward interval for a particular group.
Querier:
When enabled, the MLD snooping querier sends out periodic MLD queries that trigger MLD
report messages from the switch that wants to receive IP multicast traffic. MLD snooping listens
to these MLD reports to establish appropriate forwarding. You can enable the MLD snooping
querier on all the switches in the VLAN, but for each VLAN that is connected to switches that
use MLD to report interest in IP multicast traffic, you must configure at least one switch as the
MLD snooping querier.
profile.
Click Apply to take effect the settings.
Click Refresh to begin configuring this screen afresh.
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