Mldv2 Snooping Overview; Mldv2 Messages - Cisco WS-SUP32-GE-3B - Supervisor Engine 32 Software Configuration Manual

Understanding How MLDv2 Snooping Works
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MLDv2 Snooping Overview

MLDv2 snooping allows Catalyst 6500 series switches to examine MLDv2 packets and make
forwarding decisions based on their content.
You can configure the switch to use MLDv2 snooping in subnets that receive MLDv2 queries from either
MLDv2 or the MLDv2 snooping querier. MLDv2 snooping constrains IPv6 multicast traffic at Layer 2
by configuring Layer 2 LAN ports dynamically to forward IPv6 multicast traffic only to those ports that
want to receive it.
MLDv2, which runs at Layer 3 on a multicast router, generates Layer 3 MLDv2 queries in subnets where
the multicast traffic needs to be routed. You can configure the MLDv2 snooping querier on the switch to
support MLDv2 snooping in subnets that do not have any multicast router interfaces. For more
information about the MLDv2 snooping querier, see the
section on page
MLDv2 (on a multicast router) or the MLDv2 snooping querier (on the supervisor engine) sends out
periodic general MLDv2 queries that the switch forwards through all ports in the VLAN, and to which
hosts respond. MLDv2 snooping monitors the Layer 3 MLDv2 traffic.
PFC/DFC 3B/3BXL does not support source-only Layer 2 entries and therefore IPv6 multicast flooding
Note
cannot be prevented in a source-only network.
If a multicast group has only sources and no receivers in a VLAN, MLDv2 snooping constrains the
Note
multicast traffic to only the multicast router ports.

MLDv2 Messages

These are the MLDv2 messages:
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Catalyst Supervisor Engine 32 PISA Cisco IOS Software Configuration Guide, Release 12.2ZY
26-2
Leaving a Multicast Group, page 26-6
Understanding the MLDv2 Snooping Querier, page 26-7
26-8.
Multicast listener queries
General query—Sent by a multicast router to learn which multicast addresses have listeners.
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Multicast address specific query—Sent by a multicast router to learn if a particular multicast
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address has any listeners.
Multicast address and source specific query—Sent by a multicast router to learn if any of the
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sources from the specified list for the particular multicast address has any listeners.
Multicast listener reports
Current state record (solicited)—Sent by a host in response to a query to specify the INCLUDE
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or EXCLUDE mode for every multicast group in which the host is interested.
Filter mode change record (unsolicited)—Sent by a host to change the INCLUDE or EXCLUDE
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mode of one or more multicast groups.
– Source list change record (unsolicited)—Sent by a host to change information about multicast
sources.
Chapter 26 Configuring MLDv2 Snooping for IPv6 Multicast Traffic
"Enabling the MLDv2 Snooping Querier"
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