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Setting the maximum number of multicast groups that a port can
join
To regulate multicast traffic on a port, configure the maximum number of multicast groups that the port
can join.
When you configure this maximum number, if the number of multicast groups the port has joined exceeds
the configured maximum value, the system deletes all the forwarding entries for the port from the IGMP
snooping forwarding table, and the hosts on this port join multicast groups again until the number of
multicast groups that the port joins reaches the maximum value. When the port joins a multicast group,
if the port has been configured as a static member port, the system applies the configurations to the port
again. If you have configured simulated joining on the port, the system establishes corresponding
forwarding entry for the port after receiving a report from the simulated member host.
To set the maximum number of multicast groups that a port can join:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter Layer 2 Ethernet
interface view, Layer 2
aggregate interface view, or
port group view.
•
Enter Layer 2 Ethernet interface
view or Layer 2 aggregate
interface view:
interface
interface-type
interface-number
•
Enter port group view:
port-group
manual
port-group-name
Use either command.
3.
Set the maximum number of
multicast groups that a port
can join.
igmp-snooping group-limit
limit
[
vlan
vlan-list
]
512 by default.
Enabling multicast group replacement
For various reasons, the number of multicast groups that the switch or a port joins might exceed the upper
limit. In addition, in some specific applications, a multicast group that the switch newly joins must replace
an existing multicast group automatically. A typical example is channel switching. To view a new channel,
a user switches from the current multicast group to the new one.
To realize such requirements, you can enable the multicast group replacement function on the switch or
on a certain port. When the number of multicast groups that the switch or on the port has joined reaches
the limit, one of the following occurs:
•
If the multicast group replacement feature is disabled, new IGMP reports are automatically
discarded.
•
If the multicast group replacement feature is enabled, the multicast group that the switch or a port
newly joins automatically replaces an existing multicast group that has the lowest address.
IMPORTANT:
In the configuration, be sure to configure the maximum number of multicast groups allowed on a port (see
"
Setting the maximum number of multicast groups that a port can join
") before enabling multicast group
replacement. Otherwise, the multicast group replacement functionality will not take effect.
