Igmp-Snooping Group-Policy - 3Com Switch 4500 Family Manual

To prevent bursting traffic in the network or performance deterioration of the device caused by
excessive multicast groups, you can set the maximum number of multicast groups that the switch
should process.
When the number of multicast groups exceeds the configured limit, the switch removes its
multicast forwarding entries starting from the oldest one. In this case, the multicast packets for the
removed multicast group(s) will be flooded in the VLAN as unknown multicast packets. As a result,
non-member ports can receive multicast packets within a period of time.
To avoid this from happening, enable the function of dropping unknown multicast packets.
The keyword overflow-replace does not apply to IGMPv3 Snooping, that is, with IGMPv3
Snooping enabled, even if the keyword overflow-replace is configured, a new multicast group will
not replace an existing multicast group when the number of multicast groups reaches the maximum
value.
Examples
# Configure to allow Ethernet 1/0/1 in VLAN 2 to join a maximum of 200 multicast groups.
<Sysname>system-view
System View: return to User View with Ctrl+Z.
[Sysname] interface Ethernet 1/0/1
[Sysname-Ethernet1/0/1] igmp-snooping group-limit 200 vlan 2

igmp-snooping group-policy

Syntax
igmp-snooping group-policy acl-number [ vlan vlan-list ]
undo igmp-snooping group-policy [ vlan vlan-list ]
View
System view, Ethernet port view
Parameters
acl-number: Basic ACL number, in the range of 2000 to 2999.
vlan vlan-list: Specifies a VLAN list. With the vlan-list argument, you can provide one or more individual
VLAN IDs (in the form of vlan-id) and/or one or more VLAN ID ranges (in the form of vlan-id1 to vlan-id2,
where vlan-id2 must be greater than vlan-id1). The effective range for a VLAN ID is 1 to 4094 and the
total number of individual VLANs plus VLAN ranges cannot exceed 10.
Description
Use the igmp-snooping group-policy command to configure a multicast group filter.
Use the undo igmp-snooping group-policy command to remove the configured multicast group filter.
By default, no multicast group filter is configured.
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