Command Reference Guide

3Com Router 5000 Family and Router 6000 Family igmp robust-count ● 63
Command Reference
igmp robust-count
Purpose Use the igmp robust-count command to set the times IGMP querier sends the
IGMP specified group query packet when it receives IGMP Leave packet from the
host.
Use the undo igmp robust-count command to restore the default value.
Syntax igmp robust-count robust-value
undo igmp robust-count
Parameters robust-value
IGMP robust coefficient, indicating the times the IGMP
querier sends the IGMP specified group query packet
when it receives IGMP Leave packet from the host.
Valid values are 2 to 5.
If not specified, the default value is 2.
Example Configure the robust-value of querier on the interface Ethernet1/0/0 to 3.
[3Com-Ethernet1/0/0] igmp robust-count 3
View This command can be used in the following views:
■ Interface view
Description On a shared network, that is, when there are multiple hosts and multicast routers on
a network segment, the query router (querier for short) takes charge of maintaining
IGMP group membership on an interface. When the host in IGMP Version 2 leaves a
group, the host should send IGMP Leave packet. If IGMP querier receives the packet,
it must send the IGMP specified group query packet for robust-value times according
to the interval seconds configured via igmp lastmember-queryinterval
command (if the command is not configured, seconds is 1) and the robust coefficient
robust-value configured via igmp robust-count (if the command is not
configured, robust-value is 2). If another host receives the IGMP specified group query
packet from IGMP querier and is interested in the group, it will send IGMP
Membership Report packet within the maximum response time regulated by the
packet. If IGMP querier receives IGMP Membership Report packet from another host
within the time robust-value x seconds, it will go on maintaining the group
membership. If not, it will regard the group is overtime and stop maintaining the
group membership.
The command is only valid when IGMP query router is running in IGMP Version 2. If
the host runs in IGMP Version 1, it may not send IGMP Leave packet when it leaves a
group. At that time, the command is invalid to the host.