Specifications

Link Aggregation Overview
December 02, 2010 Page 7 of 23
ShouldanaggregatableportbeavailablewithallLAGresourcesdepletedforthissystem,theport
isplacedinLACPstandbystate.Portsinstandbystatedonotforwardtraffic.Ifallportsinitially
movedtotheattachstateforagivenLAGbecomeunavailable,aLAGresourcewillthenbe

available.LACPwillinitiateanewselectionprocessusingtheportsinstandbystate,usingthe
samerulesastheinitialprocessofformingLAGsandmovingportstotheattachedstate.
Single Port Attached State Rules
Bydefault,aLAGmustcontaintwoormoreactorandpartnerportpairsfortheLAGtobe
initiatedbythisdevice.AfeatureexiststoallowthecreationofasingleportLAGthatisdisabled
bydefault.IfsingleportLAGisenabled,asingleportLAGcan
becreatedonthisdevice.Ifsingle
portLAGisdisabled,asingleportLAGwillnotbeinitiatedbythisdevice.Ifapeerdeviceisable
toformasingleportLAGandadvertisesitswillingnesstodoso,asingleportLAGcanform.
Therearethree
conditionsunderwhichasingleportLAGcanexistandtheLAGmembercanbe
movedtotheattachedstate:
•ThesingleportLAGfeatureisenabled.
or,
•ThesingleportLAGfeatureisdisabled,butthepeerdeviceisableandwillingtoformasingle
portLAG.
or,
•Analreadyexisting
LAGconfigurationpersiststhroughadeviceormodulereset.Ifupon
resetthereisonlyasingleportactiveforanalreadyexistingLAG,thatsingleportwillmove
totheattachedstateregardlessofthesingleportLAGsetting.
LAG Port Parameters
LAGportparameterscanbechangedperport.
Table 2specifiestheLACPportparametersthatcanbechanged.
Table 2 LAG Port Parameters
Term Definition
Port Admin Key The port admin key can be set for both the actor and partner side of the link. The
admin key only affects the local device. LACP uses this value to determine which
underlying physical ports are capable of aggregating. Aggregator ports allow only
underlying ports with physical port and LAG admin keys that match to join a LAG.
Setting the physical port admin key to a different value than any LAG resource on the
device will ensure that this link does not join a LAG. Valid values are 1 - 65535.
Default value is 32768.
Port Priority Port priority can be set for both the actor and partner side of the link. The port priority
plays a role in determining which set of ports will move to the attached state and
pass traffic. The lower port priority, for the port on the system in charge of selecting
ports to move to the attached state, determines which ports will actually move to the
attached state. If a LAG is made up of ports with different speeds, setting a lower port
priority to ports with the desired speed for the LAG will ensure that those ports move
to the attached state. Port priority is also used to determine which ports join a LAG if
the number of ports available exceeds the number of ports supported for that device.
Valid values are 0 - 65535, with lower values designating higher priority. Default
value is 32768.