Understanding Igmp Version 3 Support; Default Igmp Snooping Configuration; Igmp Snooping And Igmp Snooping Querier Configuration Guidelines And Restrictions; Guidelines - Cisco 6500 Series Software Configuration Manual

Default IGMP Snooping Configuration

Understanding IGMP Version 3 Support

With Release 12.1(8a)E and later releases, IGMP snooping supports IGMP version 3. Because the Layer
2 table is (MAC-group, VLAN) based, with IGMPv3 hosts it is preferable to have only a single multicast
source per MAC-group. A single multicast source per group allows IGMPv3 hosts connected to specific
ports to receive traffic from a specific (source, group).
Default IGMP Snooping Configuration
Table 21-3
Table 21-3 IGMP Snooping Default Configuration
Feature
IGMP snooping querier
IGMP snooping
Multicast routers
IGMP snooping learning method
1. Supported in Release 12.1(8a)E and later releases.
2. PIM/DVMRP = Protocol Independent Multicast/Distance Vector Multicast Routing Protocol
IGMP Snooping and IGMP Snooping Querier Configuration
Guidelines and Restrictions
Follow these guidelines and restrictions when configuring IGMP snooping and IGMP snooping querier:

Guidelines

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Catalyst 6500 Series Switch Cisco IOS Software Configuration Guide—Release 12.1 E
21-6
shows the default IGMP snooping configuration.
1
IGMP snooping supports private VLANs. Private VLANs do not impose any restrictions on IGMP
snooping.
IGMP snooping constrains traffic in MAC multicast groups 0100.5e00.0001 to 0100.5eff.ffff.
IGMP snooping does not constrain Layer 2 multicasts generated by routing protocols.
The IGMP snooping querier supports IGMP version 2.
When enabled, the IGMP snooping querier does not start if it detects IGMP traffic from a multicast
router.
When enabled, the IGMP snooping querier starts after 60 seconds with no IGMP traffic detected
from a multicast router.
When enabled, the IGMP snooping querier disables itself if it detects IGMP traffic from a multicast
router.
You can enable the IGMP snooping querier on all the Catalyst 6500 series switches in the VLAN.
On each VLAN that is connected to switches that use IGMP to report interest in IP multicast traffic,
you must set one switch as the IGMP querier.
Default Values
Disabled
Enabled
None configured
2
PIM/DVMRP
Chapter 21 Configuring IGMP Snooping
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