Web Management Guide-R05

Table Of Contents
Chapter 16
| Multicast Filtering
Layer 2 IGMP (Snooping and Query for IPv4)
– 581
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.
If immediate leave is enabled, the following options are provided:
By Group
– 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.
By Host IP
– The switch will not send out a group-specific query when an
IGMPv2/v3 leave message is received. But will check if there are other hosts
joining the multicast group. Only when all hosts on that port leave the
group will the member port be deleted.
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. (Options:
Enabled, Disabled, Using Global Status; Default: Using Global Status)
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.
Configure Port/Trunk
Rate Limit
– The maximum rate at which IGMP membership reports can be
sent from an interface. (Range: 5-255 pps)