3com S7906E 설치 설명서

 

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Before configuring IGMP snooping querier, complete the following task:  

z 

Enable IGMP snooping in the VLAN.  

Before configuring IGMP snooping querier, prepare the following data:  

z 

IGMP general query interval,  

z 

IGMP last-member query interval,  

z 

Maximum response time to IGMP general queries, 

z 

Source address of IGMP general queries, and  

z 

Source address of IGMP group-specific queries.  

In an IP multicast network running IGMP, a multicast router or Layer 3 multicast switch is responsible for 

sending IGMP general queries, so that all Layer 3 multicast devices can establish and maintain 

multicast forwarding entries, thus to forward multicast traffic correctly at the network layer. This router or 

Layer 3 switch is called an IGMP querier.  

However, a Layer 2 multicast switch does not support IGMP, and therefore cannot send general queries 

by default. By enabling IGMP snooping on a Layer 2 switch in a VLAN where multicast traffic needs to 

be Layer-2 switched only and no multicast routers are present, the Layer 2 switch will act as the IGMP 

snooping querier to send IGMP queries, thus allowing multicast forwarding entries to be established 

and maintained at the data link layer.  

Follow these steps to enable IGMP snooping querier:  

Enter system view 

system-view 

— 

Enter VLAN view 

vlan vlan-id 

— 

Enable IGMP snooping querier 

igmp-snooping querier 

Required 

Disabled by default 

 

It is meaningless to configure an IGMP snooping querier in a multicast network running IGMP. Although 

an IGMP snooping querier does not take part in IGMP querier elections, it may affect IGMP querier 

elections because it sends IGMP general queries with a low source IP address.  

For details about IGMP querier, see IGMP Configuration of the IP Multicast Volume. 

 

You can tune the IGMP general query interval based on actual condition of the network.  

Upon receiving an IGMP query (general query or group-specific query), a host starts a timer for each 

multicast group it has joined. This timer is initialized to a random value in the range of 0 to the maximum