Understanding Mld Snooping - Cisco Catalyst 2975 Software Configuration Manual

Configuring IPv6 MLD Snooping
You can use Multicast Listener Discovery (MLD) snooping to enable efficient distribution of IP
version 6 (IPv6) multicast data to clients and routers in a switched network on the Catalyst 2975 switch.
Unless otherwise noted, the term switch refers to a standalone switch and to a switch stack.
To use IPv6, you must configure the dual IPv4 and IPv6 Switch Database Management (SDM) template
Note
on the switch. You select the template by entering the sdm prefer dual-ipv4-and-ipv6 default global
configuration command.
For related information, see these chapters:
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•
For complete syntax and usage information for the commands used in this chapter, see the command
Note
reference for this release or the Cisco IOS documentation referenced in the procedures.
This chapter includes these sections:
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•
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Understanding MLD Snooping

In IP version 4 (IPv4), Layer 2 switches can use Internet Group Management Protocol (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. In IPv6, MLD snooping
performs a similar function. With MLD snooping, 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.
MLD is a protocol used by IPv6 multicast routers to discover the presence of multicast listeners (nodes
wishing to receive IPv6 multicast packets) on its directly attached links and to discover which multicast
packets are of interest to neighboring nodes. MLD is derived from IGMP; MLD version 1 (MLDv1) is
OL-19720-02
For more information about SDM templates, see
For information about IPv6 on the switch, see
"Understanding MLD Snooping" section on page 36-1
"Configuring IPv6 MLD Snooping" section on page 36-5
"Displaying MLD Snooping Information" section on page 36-12
C H A P T E R
Chapter 8, "Configuring SDM Templates."
Chapter 35, "Configuring IPv6 Host Functions."
Catalyst 2975 Switch Software Configuration Guide
36
36-1