Report Suppression (Igmpv2) And Proxy Reporting (Igmpv3); Group Leave Processing - Cisco ASR 9000 Series Configuration Manual

IGMP Snooping Configuration at the Bridge Domain Level
• query-interval is the amount of time between general queries.
Values for the components in the GMI are obtained as follows:
• MRT is advertised in the general query, for both IGMPv2 and IGMPv3.
• If the querier is running IGMPv2, IGMP snooping uses the IGMP-snooping-configured values for the
robustness-variable and query-interval. These parameter values must match the configured values for
the querier. In most cases, if you are interacting with other Cisco routers, you should not need to explicitly
configure these values—the default values for IGMP snooping should match the default values of the
querier. If they do not, use the querier robustness-variable and querier query-interval commands to
configure matching values.
• IGMPv3 general queries convey values for robustness-variable and query-interval (QRV and QQI,
respectively). IGMP snooping uses the values from the query, making the IGMP snooping GMI exactly
match that of the querier.

Report Suppression (IGMPv2) and Proxy Reporting (IGMPv3)

The following IGMP snooping features reduce multicast traffic in a bridge domain. Both are enabled by
default.
• IGMPv2 report suppression—If the bridge domain querier is running IGMPv2, IGMP snooping suppresses
joins from a host if it has already forwarded the same join from another host during the current query
interval. IGMP snooping forwards the last leave message to all mrouter ports.
As insurance against lost reports when report suppression is enabled, IGMP snooping forwards IGMPv2
join reports the configured querier robustness-variable times for new groups. Configure the querier
robustness-variable using the querier robustness-variable command.
• IGMPv3 proxy reporting—If the bridge domain querier is running IGMPv3, IGMP snooping acts as a
proxy, generating reports from the proxy reporting address. Configure the proxy reporting address using
the system-ip-address command. The default value is 0.0.0.0.
As insurance against lost reports when proxy reporting is enabled, IGMP snooping generates and forwards
state change reports robustness-variable times, where the robustness-variable is the QRV value in the
querier's general query. The reports are forwarded at random intervals within the timeframe configured
with the unsolicited-report-timer command.
To disable report suppression and proxy reporting, use the report-suppression disable command.
The scope for the commands mentioned in this section is the bridge domain. The commands are ignored in a
profile attached to a port.

Group Leave Processing

Group Leave Options
When hosts want to leave a multicast group, they can either ignore the periodic general IGMP queries (called
a silent leave), or they can send a group-specific leave message.
IGMP snooping can respond to group leaves in the following ways:
• Last member query processing—This is the default method for processing group leaves.
Cisco ASR 9000 Series Aggregation Services Router Multicast Configuration Guide, Release 6.0.x
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Implementing Layer-2 Multicast with IGMP Snooping