Lenovo Flex System Fabric CN4093 User Manual

142 CN4093 Application Guide for N/OS 8.4
VLAN Tagging/Trunk Mode
EnterpriseNOSsoftwaresupports802.1Q VLANtagging,providing
standards‐basedVLANsupportforEthernetsystems.
TaggingplacestheVLANidentifierintheframeheaderofapacket,allowingeach
porttobelongtomultipleVLANs.Whenyouaddaporttomultip leVLANs,you
alsomustenabletaggingonthatport.
Since
taggingfundamentallychangestheformatofframestran smittedonatagged
port,youmustcarefullyplannetworkdesignstopreventtaggedframesfrom
beingtransmittedtodevicesthatdonotsupport802.1QVLANtags,ordevices
wheretaggingisnotenabled.
Importanttermsusedwiththe802.1Qtaggin gfeatureare:
 VLANidentifier(VID)—the12‐bitportionoftheVLANtagintheframeheader
thatidentifiesanexplicitVLAN.
 PortVLANidentifier(PVID) —aclassificationmechanismthatassociatesaport
withaspecificVLAN.Forexample,aportwithaPVIDof3(PVID=3)assignsall
untaggedframesreceivedonthisporttoVLAN3.Anyuntaggedframes
receivedbytheswitchareclassifiedwiththePVIDofthereceiving
port.
 Taggedframe—aframethatcarriesVLANtagginginformationintheheader.
ThisVLANtagginginformationisa32‐bitfield(VLANtag)intheframeheader
thatidentifiestheframeasbelongingtoaspecificVLAN.Untaggedframesare
marked(tagged)withthisclassificationastheyleave theswitchthrougha
port
thatisconfiguredasataggedport.
 Untaggedframe—aframethatdoesnotcarryanyVLANtagginginformation
intheframeheader.
 Untaggedmember—aportthathasbeenconfiguredasanuntaggedmemberof
aspecificVLAN.Whenanuntaggedframeexitstheswitchthroughan
untaggedmemberport,theframeheaderremainsunchanged.Whenatagged
frameexitstheswitchthroughanuntaggedmemberport,thetagisstripped
andthetagged
frameischangedtoanuntaggedframe.
 Taggedmember—aportthathasbeenconfiguredasataggedmemberofa
specificVLAN.Whenanuntaggedframeexitstheswitchthroughatagged
memberport,theframeheaderismodifiedtoincludethe32‐bittagassociated
withthePVID.Whenataggedframeexitstheswitchthrougha
taggedmember
port,theframeheaderremainsunchanged(originalVIDremains).

Lenovo Flex System Fabric CN4093 Specifications

General

Brand	Lenovo
Model	Flex System Fabric CN4093
Category	Switch
Language	English