3com 5500-ei pwr Installation Instruction

 

8 

z 

If the IGMP querier receives IGMP report messages from other hosts within the period of 

robust-value x lastmember-queryinterval, it will maintain the membership of the group.  

z 

If the IGMP querier does not receive IGMP report messages from other hosts after the period of 

robust-value x lastmember-queryinterval, it considers that the group has no members on the local 

subnet and removes the forwarding table entry for the group.  

 

You can use the igmp max-response-time command to set the maximum response time for general 

IGMP query messages, while that of an IGMP group-specific query message is determined by 

robust-value x lastmember-queryinterval. 

 

The procedure is only fit for the occasion where IGMP queriers run IGMP version 2.  

On a subnet containing multiple IGMP-enabled interfaces, the one with the lowest IP address becomes 

the IGMP querier. If non-querier interfaces receive no query message within the period configured in the 

igmp timer other-querier-present command, the current IGMP querier is considered to be down. In 

this case, a new IGMP querier election process takes place.  

When the host receives a general query message, it will set a timer for each of its multicast groups. The 

timer value is selected from 0 to the maximum response time at random. When the value of a timer 

decreases to 0, the host will send the membership information of the multicast group.  

By configuring reasonable maximum response time, you can enable the host to respond to the query 

information quickly and enable the Layer 3 switch to understand the membership information of 

multicast groups quickly.  

Follow these steps to configure options related to IGMP query messages: 

Enter system view 

— 

Enter interface view 

interface interface-type 
interface-number 

— 

Configure the query interval 
(interval of sending general 
queries) 

igmp timer query seconds 

Optional 

60 seconds by default.  

Configure the interval of 
sending IGMP group-specific 
query messages 

igmp 
lastmember-queryinterval 
seconds 

Optional 

1 second by default  

Configure the number of times 
of sending IGMP group-specific 
query messages 

igmp robust-count 
robust-value 

Optional 

2 by default.  

Configure the other querier 
present timer 

igmp timer 
other-querier-present 
seconds 

Optional 

The system default is 120 
seconds, namely twice the 
query interval.