Operation Manual – Multicast
H3C S3100 Series Ethernet Switches
Chapter 2 IGMP Snooping Configuration
2-15
2.2.11 Configuring a VLAN Tag for Query Messages
By configuring the VLAN in which IGMP general and group-specific queries forwarded
and sent by IGMP Snooping switches are transmitted, you can enable multicast packet
forwarding between different VLANs In a Layer-2 multicast network environment.
Table 2-17
Configure VLAN Tag for query message
Operation
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
Note:
It is not recommended to configure this function while the multicast VLAN function is in
effect.
2.2.12 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 switch.
Table 2-18
Configure multicast VLAN on the Layer 3 switch
Operation
Command
Remarks
Enter system view
system-view
—
Create a multicast VLAN
and enter VLAN view
vlan vlan-id
—