Allied Telesis AR400 manual Preventing an All Groups entry for a port

Stopping snoopers from snooping non-IGMP messages > Preventing an All Groups entry for a port

Preventing an All Groups entry for a port

This section stops port 24 from being in switch 2’s All Groups entry, then adds it back again.

Disabling All Groups entry for a port

You can avoid the All Groups entries shown above by simply disabling the All Groups entry for the port that switch 2 uses to connect to the router.

Manager Switch 2> disable ip igmp allgroups=24

Info (1005003): Operation successful.

Manager Switch 2> show igmpsnooping

IGMP Snooping

------------------------------------------------------------------------

Status			Enabled
Disabled All-groups		ports	........ 24
Vlan	Name (vlan id)	..... default (1)
Fast	Leave		Off
Group List
No	group memberships.
Vlan	Name (vlan id)	..... vlan100 (100)
Fast	Leave		Off

Group	List
Group. 224.12.13.14			Entry timeout	164	secs
Ports		None
All	Groups		Entry timeout	251	secs
Ports		24#,25

------------------------------------------------------------------------

Port 24 is now accompanied by a hash. This is because All Groups was disabled for the port while the port was part of All Groups. The switch will keep sending port 24 traffic for the group 224.12.13.14 until either port 24’s internal timer or the timer for the group 224.12.13.14 hits zero.

Note: The switch keeps an internal timer for each port in its All Groups list, which is separate from the All Groups entry timeout displayed in output of the command show igmpsnooping. There are no commands to view the internal timer, but every time the switch receives a new IGMP (or in this case OSPF) message the timer resets. This timer means that if the router stopped sending OSPF messages to the port, the switches would eventually drop the relevant entries from their All Groups lists.

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