LevelOne GTL-2691 - Manual (Page 1198)

C HAPTER 42 | Multicast Filtering Commands
IGMP Snooping
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◆ Advertisements are sent by routers to advertise that IP multicast
forwarding is enabled. These messages are sent unsolicited periodically
on all router interfaces on which multicast forwarding is enabled. They
are sent upon the expiration of a periodic timer, as a part of a router's
start up procedure, during the restart of a multicast forwarding
interface, and on receipt of a solicitation message. When the multicast
services provided to a VLAN is relatively stable, the use of solicitation
messages is not required and may be disabled using the no ip igmp
snooping vlan mrd command.
◆ This command may also be used to disable multicast router solicitation
messages when the upstream router does not support MRD, to reduce
the loading on a busy upstream router, or when IGMP snooping is
disabled in a VLAN.
E XAMPLE
This example disables sending of multicast router solicitation messages on
VLAN 1.
Console(config)#no ip igmp snooping vlan 1 mrd
Console(config)#
ip igmp snooping
vlan proxy-address
This command configures a static source address for locally generated
query and report messages used by IGMP proxy reporting. Use the no form
to restore the default source address.
S YNTAX
[no] ip igmp snooping vlan vlan-id proxy-address source-address
vlan-id - VLAN ID (Range: 1-4093)
source-address - The source address used for proxied IGMP query
and report, and leave messages. (Any valid IP unicast address)
D EFAULT S ETTING
0.0.0.0
C OMMAND M ODE
Global Configuration
C OMMAND U SAGE
IGMP Snooping uses a null IP address of 0.0.0.0 for the source of IGMP
query messages which are proxied to downstream hosts to indicate that it
is not the elected querier, but is only proxying these messages as defined
in RFC 4541. The switch also uses a null address in IGMP reports sent to
upstream ports.
Many hosts do not implement RFC 4541, and therefore do not understand
query messages with the source address of 0.0.0.0. These hosts will
therefore not reply to the queries, causing the multicast router to stop
sending traffic to them.