Enterasys SecureStack C2 C2G170-24

Link Aggregation Control Protocol (LACP)
7-38 Port Configuration
Link Aggregation Control Protocol (LACP)
Usingmultiplelinkssimultaneouslytoincreasebandwidthisadesirableswitchfeature,which
canbeaccomplishedifbothsidesagreeonasetofportsthatarebeingusedasaLinkAggregation
Group(LAG).OnceaLAGisformedfromselectedports,problemswithloopingcanbeavoided
sincethe
SpanningTreecantreatthisLAGasasingleport.
Enabledbydefault,theLinkAggregationControlProtocol(LACP)logicallygroupsinterfaces
togethertocreateagreaterbandwidthuplink,orlinkaggregation,accordingtotheIEEE802.3ad
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tha t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.
Caution: Link aggregation configuration should only be performed by personnel who are
knowledgeable about Spanning Tree and Link Aggregation, and fully understand the ramifications
of modifications beyond device defaults. Otherwise, the proper operation of the network could be
at risk.
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.