3com 5500-ei pwr Installation Instruction

 

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By configuring the VLAN tag carried in IGMP general and group-specific queries forwarded and sent by 

IGMP Snooping switches, you can enable multicast packet forwarding between different VLANs In a 

Layer-2 multicast network environment. 

Follow these steps to configure VLAN tag for query message: 

Enter system view 

system-view 

— 

Configure a VLAN tag for query 
messages 

igmp-snooping 
vlan-mapping vlan vlan-id 

Required 

By default, the VLAN tag in 
IGMP general and 
group-specific query messages 
is not changed. 

 

It is not recommended to configure this function while the multicast VLAN function is in effect. 

 

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. 

Follow these steps to configure multicast VLAN on the Layer 3 switch:  

Enter system view 

— 

Create a multicast VLAN and 
enter VLAN view 

vlan vlan-id 

— 

Return to system view 

— 

Enter VLAN interface view 

interface Vlan-interface 
vlan-id 

— 

Enable IGMP 

Required 

By default, the IGMP feature is 
disabled. 

Return to system view 

—