Edge-Core ECS4810-12M Layer 2 Management Manual page 611

If immediate leave is not used, a multicast router (or querier) will send
a group-specific query message when an IGMPv2 group leave message
is received. The router/querier stops forwarding traffic for that group
only if no host replies to the query within the specified time out period.
Note that this time out is set to Last Member Query Interval *
Robustness Variable (fixed at 2) as defined in RFC 2236.
If immediate leave is enabled, the switch assumes that only one host is
connected to the interface. Therefore, immediate leave should only be
enabled on an interface if it is connected to only one IGMP-enabled
device, either a service host or a neighbor running IGMP snooping.
This attribute is only effective if IGMP snooping is enabled, and IGMPv2
snooping is used.
Multicast Router Discovery – MRD is used to discover which
◆
interfaces are attached to multicast routers. (Default: Disabled)
General Query Suppression – Suppresses general queries except for
◆
ports attached to downstream multicast hosts. (Default: Disabled)
By default, general query messages are flooded to all ports, except for
the multicast router through which they are received.
If general query suppression is enabled, then these messages are
forwarded only to downstream ports which have joined a multicast
service.
Proxy Reporting – Enables IGMP Snooping with Proxy Reporting.
◆
(Default: Based on global setting)
When proxy reporting is enabled with this command, the switch
performs "IGMP Snooping with Proxy Reporting" (as defined in DSL
Forum TR-101, April 2006), including last leave, and query
suppression.
Last leave sends out a proxy query when the last member leaves a
multicast group, and query suppression means that specific queries are
not forwarded from an upstream multicast router to hosts downstream
from this device.
Rules Used for Proxy Reporting
When IGMP Proxy Reporting is disabled, the switch will use a null IP
address for the source of IGMP query and report messages unless a
proxy query address has been set.
When IGMP Proxy Reporting is enabled, the source address is based on
the following criteria:
If a proxy query address is configured, the switch will use that
■
address as the source IP address in general and group-specific
query messages sent to downstream hosts, and in report and leave
messages sent upstream from the multicast router port.
If a proxy query address is not configured, the switch will use the
■
VLAN's IP address as the IP source address in general and group-
specific query messages sent downstream, and use the source
address of the last IGMP message received from a downstream host
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HAPTER
Layer 2 IGMP (Snooping and Query)