Digisol DG-FS4526E, Management Manual

Page: 530 / 1162

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HAPTER
18 | Multicast Filtering
Layer 2 IGMP (Snooping and Query)
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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: Enabled)
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 neither specific
queries nor general queries are forwarded from an upstream multicast
router to hosts downstream from this device.
Interface Version – Sets the protocol version for compatibility with
other devices on the network. This is the IGMP Version the switch uses
to send snooping reports. (Range: 1-3; Default: 2)
This attribute configures the IGMP report/query version used by IGMP
snooping. Versions 1 - 3 are all supported, and versions 2 and 3 are
backward compatible, so the switch can operate with other devices,
regardless of the snooping version employed.
Query Interval – The interval between sending IGMP proxy general
queries. (Range: 2-31744 seconds; Default: 125 seconds)
An IGMP general query message is sent by the switch at the interval
specified by this attribute. When this message is received by
downstream hosts, all receivers build an IGMP report for the multicast
groups they have joined.