HP ProCurve 6120G/XG Configuration Manual page 312

Port Trunking
Trunk Group Operation Using LACP
Figure 11-11. Blocked Ports with LACP
■
Figure 11-12. A Dynamic LACP Trunk Forming in a VLAN Can Cause a Traffic Loop
Easy control methods include either disabling LACP on the selected ports or
configuring them to operate in static LACP trunks.
11-24
ProCurve(eth-B1-B8)# show lacp
PORT LACP
NUMB ENABLED
---- -------
B1 Active
B2 Active
B3 Active
B4 Active
B5 Active
B6 Active
B7 Active
B8 Active
If there are ports that you do not want on the default VLAN, ensure that
they cannot become dynamic LACP trunk members. Otherwise a traffic
loop can unexpectedly occur. For example:
VLAN-1
(Default
VLAN)
VLAN-2
If the ports in VLAN 2 are configured to allow a dynamic trunk (and GVRP is disabled), adding a
second link in VLAN 2 automatically forms a dynamic LACP trunk and moves the trunk to VLAN-1
(the default VLAN), which creates a traffic loop in VLAN 1 between the two switches and
eliminates the link in VLAN 2 between the two switches.
LACP
TRUNK PORT
GROUP STATUS
------- -------
Dyn1 Up
Dyn1 Up
Dyn1 Up
Dyn1 Up
Dyn1 Blocked
Dyn1 Blocked
B7 Down
B8 Down
VLAN-1
VLAN-1
(Default
(Default
VLAN)
VLAN)
VLAN-2
VLAN-2
LACP LACP
PARTNER STATUS
------- -------
Yes Success
Yes Success
Yes Success
Yes Success
Yes Failure
Yes Failure
No Success
No Success
VLAN-1
(Default
VLAN)
VLAN-2