2-13
z Before configuring a simulated host, enable IGMP Snooping in VLAN view first.
z The port to be configured must belong to the specified VLAN; otherwise the configuration does not
take effect.
z You can use the source-ip source-address command to specify a multicast source address that
the port will join as a simulated host. This configuration takes effect when IMGPv3 Snooping is
enabled in the VLAN.
Configuring a VLAN Tag for Query Messages
By configuring the VLAN tag carried in IGMP general and group-specific queries forwarded and sent by
IGMP Snooping devices and by configuring the VLAN mapping function, you can enable multicast
packet forwarding between different VLANs In a Layer-2 multicast network environment.
For description about VLAN mapping, see “QoS-QoS Profile”.
Follow these steps to configure VLAN Tag for query message:
To do… Use the command… Remarks
Enter system view
system-view
—
Enable IGMP Snooping
igmp-snooping enable
Required
By default, IGMP Snooping is disabled.
Configure a VLAN tag
for query messages
igmp-snooping
vlan-mapping vlan
vlan-id
Required
By default, no VLAN tag is configured for
general and group-specific query messages
sent or forwarded by IGMP Snooping.
Configuring Multicast VLAN
In traditional multicast implementations, when users in different VLANs listen to the same multicast
group, the multicast data is copied on the multicast router for each VLAN that contains receivers. This is
a big waste of network bandwidth.
In an IGMP Snooping environment, by configuring a multicast VLAN and adding ports to the multicast
VLAN, you can allow users in different VLANs to share the same multicast VLAN. This saves bandwidth
because multicast streams are transmitted only within the multicast VLAN. In addition, because the
multicast VLAN is isolated from user VLANs, this method also enhances the information security.
Multicast VLAN is mainly used in Layer 2 switching, but you must make the corresponding
configurations on the Layer 3 device.
Follow these steps to configure multicast VLAN on the Layer 3 device:
To do… Use the command… Remarks
Enter system view
system-view
—
Create a multicast VLAN and
enter VLAN view
vlan vlan-id
—
Return to system view
quit
—
