Zte ZXR10 2900E Series - Figure 5-8 MSTP Topological Structure; Table 5-1 Port Role and Port State

Chapter5ServiceConguration
Figure5-8MSTPTopologicalStructure
Theportshavedifferentroles:
lMaster:TheporttypeisintroducedintheMSTPprotocol.Whenmultipledifferent
areasexist,themasterportistheportwiththeminimalcosttotheroot.
lRoot:Theportthathastheminimalcosttotherootbridgeandtakeschargein
forwardingdatatotherootnode.Whenmultipleportshavethesamecosttotheroot
bridge,theportwiththelowestportprioritybecomestotherootport.
lDesignated:Theporttransmitsdatatotheswitchdownward,andsendstheSTP
protocolmessagetomaintainthestateofSTP .
lBackup:TheportreceivestheSTPmessage,whichprovesthatthereexistsaloop
totheportitself.
lAlternate:TheportreceivesexcessSTPprotocolmessagesfromotherequipment.
However,whentheoriginallinkfails,theportbecomestransmittingandmaintainsthe
networktakingtheplaceofthefaultyport.
lEdged:Theportisusedtoconnecttheterminalequipment,forexample,PC.The
portdoesnotparticipateinthecalculationbeforetheSTPisstable,andthestatecan
beswitchedfast.
Accordingtotheportrole,theportstateisdifferentafterthecalculationbecomessteady.
Fortherelationshipsbetweentheportroleandtheportstate,refertoT able5-1.
Table5-1PortRoleandPortState
PortRolePortState
MasterForward
RootForward
DesignatedForward
BackupDiscard
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SJ-20130731155059-002|2013-11-27(R1.0)ZTEProprietaryandCondential