Explicit Host Tracking; Mldv2 Messages; Source-Based Filtering - Cisco 7604 Configuration Manual

Chapter 29 Configuring MLDv2 Snooping for IPv6 Multicast Traffic

MLDv2 Messages

MLDv2 uses these messages:
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Source-Based Filtering

MLDv2 uses source-based filtering, which enables hosts and routers to specify which multicast sources
should be allowed or blocked for a specific multicast group. Source-based filtering either allows or
blocks traffic based on the following information in MLDv2 messages:
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Because the Layer 2 table is (MAC-group, VLAN) based, with MLDv2 hosts it is preferable to have only
a single multicast source per MAC-group.
Source-based filtering is not supported in hardware. The states are maintained only in software and used
Note
for explicit host tracking and statistics collection.

Explicit Host Tracking

MLDv2 supports explicit tracking of membership information on any port. The explicit-tracking
database is used for fast-leave processing, proxy reporting, and statistics collection. When explicit
tracking is enabled on a VLAN, the MLDv2 snooping software processes the MLDv2 report it receives
from a host and builds an explicit-tracking database that contains the following information:
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OL-4266-08
Multicast listener queries:
– General query—Sent by a multicast router to learn which multicast addresses have listeners.
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
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
mode of one or more multicast groups.
– Source list change record (unsolicited)—Sent by a host to change information about multicast
sources.
Source lists
INCLUDE or EXCLUDE mode
The port connected to the host
The channels reported by the host
The filter mode for each group reported by the host
The list of sources for each group reported by the hosts
The router filter mode of each group
For each group, the list of hosts requesting the source
Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
Understanding How MLDv2 Snooping Works
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