| Multicast Filtering Commands
ip igmp snooping vlan
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
This example disables sending of multicast router solicitation messages on VLAN 1.
Console(config)#no ip igmp snooping vlan 1 mrd
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.
[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)
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.
– 472 –