Enterasys Networks D2G124-12, D2G124-12P LACP Operation, LACP Terminology

Link Aggregation Control Protocol (LACP)
4-34 Port Configuration
standard.ThisstandardallowstheswitchtodeterminewhichportsareinLAGsandconfigure
themdynamically.SincetheprotocolisbasedontheIEEE802.3adspecification,anyswitchfrom
anyvendorthatsupportsthisstandardcanaggregatelinksautomatically.
802.3adLACPaggregationscanalsoberuntoend‐users(thatis,aserver)ortoarouter.
LACP Operation
Foreachaggregatableportinthedevice,LACP:
• Maintainsconfigurationinformation(reflectingtheinherentpropertiesoftheindividuallinks
aswellasthoseestablishedbymanagement)tocontrolaggregation.
•ExchangesconfigurationinformationwithotherdevicestoallocatethelinktoaLink
AggregationGroup(LAG).
• AttachestheporttotheaggregatorusedbytheLAG,anddetachestheportfromthe
aggregatorwhenitisnolongerusedbytheLAG.
•Usesinformationfromthepartnerdevice’slinkaggregationcontrolentitytodecidewhether
toaggregateports.
TheoperationofLACPinvolvesthefollowingactivities:
•Checkingthatcandidatelinkscanactuallybeaggregated.
• ControllingtheadditionofalinktoaLAG,andthecreationofthegroupifnecessary.
• Monitoringthestatusofaggregatedlinkstoensurethattheaggregationisstillvalid.
•RemovingalinkfromaLAGifitsmembershipisnolongervalid,andremovingthegroupifit
nolongerhasanymemberlinks.
InordertoallowLACPtodeterminewhetherasetoflinksconnecttothesamedevice,andto
determinewhetherthoselinksarecompatiblefromthepointofviewofaggregation,itis
necessarytobeabletoestablish
•Agloballyuniqueidentifierforeachdevicethatparticipatesinlinkaggregation.
•Ameansofidentifyingthesetofcapabilitiesassociatedwitheachportandwitheach
aggregator,asunderstoodbyagivendevice.
•AmeansofidentifyingaLAGanditsassociatedaggregator.
LACP Terminology
Tabl e 4‐15defineskeyterminologyusedinLACPconfiguration.
Note: Earlier (proprietary) implementations of port aggregation referred to groups of aggregated
ports as “trunks”.
Note: A given link is allocated to, at most, one Link Aggregation Group (LAG) at a time. The
allocation mechanism attempts to maximize aggregation, subject to management controls.
Note: The path cost of a LAG port will be displayed as zero when it is not an active link.