3com DUA1750-2BAA01 Manual De Usuario
3Com Switch 8800 Configuration Guide
Chapter 27 IGMP Configuration
27-2
address is elected as the querier when there are multiple multicast routers on the same
network segment.
II. Leaving group mechanism
In IGMP Version 1, hosts leave the multicast group quietly without informing the
multicast router. In this case, the multicast router can only depend on the timeout of the
response time of the multicast group to confirm that hosts leave the group. In Version 2,
when a host is intended to leave, it will send a leave group message if it is the host who
responds to the latest membership query message.
III. Specific group query
In IGMP Version 1, a query of a multicast router is targeted at all the multicast groups
on the network segment, which is known as General Query.
In IGMP Version 2, Group-Specific Query is added besides general query. The
destination IP address of the query packet is the IP address of the multicast group. The
group address domain in the packet is also the IP address of the multicast group. This
prevents the hosts of members of other multicast groups from sending response
messages.
IV. Max response time
The Max Response Time is added in IGMP Version 2. It is used to dynamically adjust
the allowed maximum time for a host to respond to the group query message.
27.2 IGMP Configuration
After the multicast function is enabled, you must enable IGMP on the interface first and
then perform other IGMP configurations.
1)
IGMP basic configuration includes:
z
Enabling multicast
z
Enabling IGMP on an interface
2)
IGMP advanced configuration includes:
z
Configuring a router to join specified multicast group
z
Controlling the access to IP multicast groups
z
Configuring the IGMP query message interval
z
Configuring the IGMP version
z
Configuring the IGMP querier present timer
z
Configuring the maximum query response time
z
Configuring the times of sending IGMP Group-Specific Query packet
z
Configuring the interval of sending IGMP Group-Specific Query packet
z
Configuring the limit of IGMP groups on an interface
z
Deleting IGMP Groups Joined on an Interface