z

z

z

Before configuring a simulated host, enable IGMP Snooping in VLAN view first.

The port to be configured must belong to the specified VLAN; otherwise the configuration does not take effect.

You can use the source-ipsource-addresscommand 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.

 

 

 

 

 

 

 

 

 

igmp-snooping

Required

 

Configure a VLAN tag

By default, no VLAN tag is configured for

 

vlan-mapping vlan

 

for query messages

general and group-specific query messages

 

vlan-id

 

 

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

vlan vlan-id

enter VLAN view

 

 

 

 

 

Return to system view

quit

 

2-13

 

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3Com WX3000 operation manual Configuring a Vlan Tag for Query Messages, Configuring Multicast Vlan, Vlan-mapping vlan