3Com SuperStack 4 Configuration Manual page 172

184 C 7: M
HAPTER ULTICAST
P
ROTOCOL
Setting the maximum response time reasonably can enable the host to respond to
query messages quickly. In this case, the router can fast master the existing status
of the members of the multicast group.
Perform the following configuration in Interface view.
Table 195 Configuring the maximum response time for IGMP query message
Operation
Configure the maximum response time for IGMP
query message
Restore the maximum query response time to the
default value
The smaller the maximum query response time value, the faster the router prunes
groups. The actual response time is a random value in the range from 1 to 25
seconds. By default, the maximum query response time is 10 seconds.
Configuring the Limit of IGMP Groups on an Interface
If there is no limit to the number of IGMP groups added on a router interface or a
router, the router memory may be exhausted, which may cause router failure.
You can set number limit for the IGMP groups added on the interface, but not the
number limit for the IGMP groups added in the router, which is defined by the
system.
Perform the following configuration in Interface view.
Table 196 Configuring the limit of IGMP groups on an interface
Operation
Configure the limit of IGMP groups on
an interface
Restore the limit of IGMP groups on an
interface to the default value
By default, the maximum number of IGMP groups on an interface is 1024.
If the number of IGMP groups on an interface has exceeded the specified value
during configuration, no IGMP group will be deleted.
Configuring a Router to Join Specified Multicast Group
Usually, the host operating IGMP will respond to IGMP query packet of the
multicast router. In case of response failure, the multicast router will consider that
there is no multicast member on this network segment and will cancel the
corresponding path. Configuring one interface of the router as multicast member
can avoid such problem. When the interface receives IGMP query packet, the
router will respond, thus ensuring that the network segment where the interface
is connected can normally receive multicast packets.
For a Switch 5500G-EI, you can configure a port in a VLAN interface to join a
multicast group.
Command
igmp max-response-time
undo igmp max-response-time
Command
limit
igmp group-limit
undo igmp group-limit
seconds