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Configuring IGMP Snooping and MVR
How to Configure IGMP Snooping and MVR
permit—Specifies that matching addresses are permitted.
range—Specifies a range of IP addresses for the profile. You can enter a single IP address or a range with a start and
an end address.
The default is for the switch to have no IGMP profiles configured. When a profile is configured, if neither the permit nor
deny keyword is included, the default is to deny access to the range of IP addresses.
To control access as defined in an IGMP profile, use the ip igmp filter interface configuration command to apply the
profile to the appropriate interfaces. You can apply IGMP profiles only to Layer 2 access ports; you cannot apply IGMP
profiles to routed ports or SVIs. You cannot apply profiles to ports that belong to an EtherChannel port group. You can
apply a profile to multiple interfaces, but each interface can have only one profile applied to it.
IGMP Throttling Action
After you set the maximum number of IGMP groups that a Layer 2 interface can join, you can configure an interface to
replace the existing group with the new group for which the IGMP report was received by using the ip igmp max-groups
action replace interface configuration command. Use the no form of this command to return to the default, which is to
drop the IGMP join report.
Follow these guidelines when configuring the IGMP throttling action:
This restriction can be applied only to Layer 2 ports. You can use this command on a logical EtherChannel interface
but cannot use it on ports that belong to an EtherChannel port group.
When the maximum group limitation is set to the default (no maximum), entering the ip igmp max-groups action
{deny | replace} command has no effect.
If you configure the throttling action and set the maximum group limitation after an interface has added multicast
entries to the forwarding table, the forwarding-table entries are either aged out or removed, depending on the
throttling action.
— If you configure the throttling action as deny, the entries that were previously in the forwarding table are not
removed but are aged out. After these entries are aged out and the maximum number of entries is in the
forwarding table, the switch drops the next IGMP report received on the interface.
— If you configure the throttling action as replace, the entries that were previously in the forwarding table are
removed. When the maximum number of entries is in the forwarding table, the switch replaces a randomly
selected entry with the received IGMP report.
To prevent the switch from removing the forwarding-table entries, you can configure the IGMP throttling action
before an interface adds entries to the forwarding table.
How to Configure IGMP Snooping and MVR
Configuring IGMP Snooping
Enabling or Disabling IGMP Snooping
By default, IGMP snooping is globally enabled on the switch. When globally enabled or disabled, it is also enabled or
disabled in all existing VLAN interfaces. IGMP snooping is by default enabled on all VLANs, but can be enabled and
disabled on a per-VLAN basis.
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