HP manual 243

Port Trunking

Port Status and Configuration

Switch “A” with ports set to LACP passive (the default).

Switch “A” with ports set to LACP active.

Switch “B” with ports set to LACP passive (the default).

Dynamic LACP trunk cannot automatically form because both ends of the links are LACP passive.

(In this case STP blocking is needed to prevent a loop.

Switch “B” with ports set to LACP passive (the default).

Dynamic LACP trunk automatically forms because both ends of the links are LACP and at least one end is LACP active. (STP is not needed, and the clear advantages are increased bandwidth and fault-tolerance.)

	Figure 12-10. Example of Criteria for Automatically Forming a Dynamic LACP Trunk
	Syntax: interface < port-list > lacp active
	This example uses ports C4 and C5 to enable a dynamic LACP trunk group.
	HPswitch(config)# interface c4-c5 lacp active
	Removing Ports from a Dynamic LACP Trunk Group. To remove a port
	from dynamic LACP trunk operation, you must turn off LACP on the port. (On
	a port in an operating, dynamic LACP trunk, you cannot change between LACP
	Active and LACP passive without first removing LACP operation from the
	port.)
C a u t i o n	Unless STP is running on your network, removing a port from a trunk can
	result in a loop. To help prevent a broadcast storm when you remove a port
	from a trunk where STP is not in use, HP recommends that you first disable
	the port or disconnect the link on that port.

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