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LANTechnologies
InformationNetworkCenter
BeijingUniversityofPostsandTelecommunications
?2013
i
Objectives
oIdentifythepositionofdatalinklayerinthe
OSI/rmstructure.
oIdentifyanddescribethebasicoperationof
EthernetandotherLANtechnologies.
oDescribehowEthernetandIEEE802.3nodes
respondtocongestionproblems.
oIdentifythetypesofphysicalconnectorsand
cablingcommonlyusedwithdifferentLANs.
oIdentifytherelationshipofadjacentlayersto
DLL.
oDistinguishbetweenthevariousversionsof
IEEE802.3implementations.
oProspectthefutureofhighspeedLAN
technologies.
2
Majortopics
oLANProtocolArchitecture
oStandards
oMajorTechnology
Ethernet/FastEthernet/GbE/lOGbE
TokenRing
?FDDI
WirelessLAN
oCharacteristicsofLANs
3
LocalAreaNetworks
oOptimizedforamoderatesizegeographic
area.
oAlldevicesareattachedtoashared
medium.
oAtransmissionfromanyonedevicecan
bereceivedbyallotherdevicesattached
tothesamenetwork.
oMediumaccesscontrol(MAC)protocols
arerequiredtoarbitratestheaccessto
thesharedmediumsinceonlyonestation
shouldbeallowedtousethemediumata
time.
4
LANProtocolArchitecture(IEEE802
referencemodel)
OSIKekreiHT
oArchitectureModel
developedbyIEEE
802committee
oLowerlayersof
OSImodel
Physical
Logicallinkcontrol
(LLC)
Mediaaccess
control(MAC)
5
LAN協(xié)議結(jié)構(gòu)
LANProtocolArchitecture
oLogicallinkcontrolOSIRritrtiHe
Model
layer
Interfacetohigher
levels
Providesaddressing
anddatalinkcontrol
functionalities
oMediumAccess
Controllayer
Governaccessto
transmissionmedium
ForthesameLLC,
severalMACoptions
maybeavailable
6
MAC協(xié)議
MACProtocols
oChannelPartitioning(Reservation)
Dividechannelintosmaller"pieces"(timeslots,
frequency)
Allocatepiecetonodeforexclusiveuse
oRandomAccess(Contention)
Allstationscontendfortimeonthemediumtransmitting
wheneverthetransmissionmediumismadeavailable-
Allowcollisions
"recover"fromcollisions
o“Takingturns"(RoundRobin)
Eachstationinturnisgiventheopportunitytotransmit
Duringtheopportunity,thestationmaydeclineto
transmitormaytransmitsubjecttoaspecifiedupper
bound
Whenastationfinished,itrelinquishesitsturn,andthe
rightispassedtothenextstation
7
MACProtocols(comparison)
oManystationshavedatatotransmit
Roundrobintechniqueswillbeefficient
oOnlyafewstationshavedatatotransmit
Overheadinpassingturnfromstationto
stationasmoststationwillnottransmit
Streamtrafficsuchasvoicecommunication
(lengthyandfairlycontinuous)
oReservationtechniques
Burstytrafficsuchasinteractiveterminaltype
traffic(shortandsporadic)
oContentiontechniques
8
OSIReference
ModelOSIProtocolSuite
_jCMIPDS|_^門~八”「j7HsVTF「
ASES
ApplicationACSE11ROSE11RTSE||CCRSE||二?.|
PisssntationPresentationS?ivICG.-'PresentationProtocol
SesssionSessionSSIVIC?.'SessionProtocol
TranspoilTPOTP1TP2TP3TP4
CONP/CMNSCLNP/CLNS
Network
IS-ISES-IS
DataLinkIEEE802.3耗三管⑸|乂”
802.2TokenRingFDD
PhysicalIEEE802.3TokenRingFDDIX.25
HairKvar?Handwar?HanchvareHanchvar?
9
Majortopics
oLANProtocolArchitecture
oStandards
oMajorTechnology
Ethernet/FastEthernet/GbE/lOGbE
TokenRing
?FDDI
WirelessLAN
oCharacteristicsofLANs
10
MilestonesforEthernet
o1982/10IEEE802.3
o1990/4Switch
o1993Fullduplex
o1995/3100MbpsIEEE802.3p
o1998/61000MbpsIEEE802.3z,ab
o2000/1010GIEEE802.3ae
o2010/640G/100G802.3ba
http:〃www上/new/source/226.html
ii
LANStandards
oANSI/IEEEStd8021990,IEEEStandardsforLAN/MAN:
OverviewandArchitecture.
o802.IB1992,IEEEStandardsforLocalandMetropolitanArea
Networks:LAN/MANManagement.
o802.21989LLC
o802.31993(CSMA/CD)Type10BASE-X
o802.3u1995100MbpsFastEthernet
o802.3z1998GigabitEthernet,onfiberopticcable
o802.4Token-PassingBusSpecifications
o802.5eTokenRingSpecifications
o802.6DistributedQueueDualBus(DQDB)forMAN
o802.71989,BroadbandLocalAreaNetworks
o802.8FiberOpticTAG
o802.9IsochronousServicesCSMA/CDMACService
o802.101992,IEEEStandardsforInteroperableLAN/MAN
Security
o802.12,LAN/MANDemandPriority
LANStandards(Conf)
o802,11WirelessLANWorkingGroup
o802.14CableModemWorkingGroup
o802.15WirelessPersonalAreaNetwork(WPAN)
WorkingGroup
o802,16BroadbandWirelessAccessWorkingGroup
o802.17ResilientPacketRingWorkingGroup
o802.18RadioRegulatoryTAG
o802.19CoexistenceTAG
o802.20MobileBroadbandWirelessAccess(MBWA)
WorkingGroup
o802.22WirelessRegionalAreaNetwork(WRAN)
13
IEEE802family
f
z
n
o
w?8022LOGICALLINKCOMTROL
sLlJ
crn
Ol
LoH
z
COMUJlDATA
B-u
工s802.1BRIDGING
uLINK
QcLAYER
<
II<z
4<
Ms
山802.3802.4802.5802.6802.9802.11802.1280214
一L
A?MEDIUMMEDIUMMEDIUMMEDIUMMEDIUMMEDIUMMEDIUMMEDIUM
H0e
W8ACCESSACCESSACCESSACCESSACCESSACCESSACCESSACCESS
>
O
N
o802.3802.4802.5802.6802.9802.11802.12802.14PHYSICAL
?PHYSICSPHYSICALPHYSICALPHYSICALPHYSICALT-JPHYSICALLAYER
,FomieflvIEEEStd802.1A.
14
StandardizedMediumAccessControl
Techniques
BusTopologyRingTopology
RoundRobinTokenBusTokenRing
(IEEE802.4)(IEEE802.5,
FDDI)
ReservationDQDB(IEEE
802.6)
ContentionCSMA/CD
(IEEE802.3)
15
主要的LAN技術(shù)
CommonLANtechnologies
100BaseTTokenRing/IEEE802.5
16
主要技術(shù)要點(diǎn)
MajorTechPoints
oTopology
oMediaaccess
oAddressscheme
oProtocolstack
oTransmissionmedia
oTransmissionmethod
oDevice
oSpecifictechnologies
17
Majortopics
oLANProtocolArchitecture
oStandards
oMajorTechnology
Ethernet/FastEthernet/GbE/lOGbE
TokenRing
?FDDI
WirelessLAN
oCharacteristicsofLANs
18
EthernetTechnology
19
AdrawingofthefirstEthernet
systembyBobMetcalfe
“AltoAlohaNetwork^^
to
"luminiferousether99network
20
Ethernetinearlydays
oEthernetisabasebandLANspecificationinvented
byXeroxCorparound70Jsthatoperatesat10
Mbpsusingcarriersensemultipleaccesscollision
detect(CSMA/CD)torunovercoaxialcable.
oThetermEthernetisoftenusedtorefertoall
CSMA/CDLANs.Ethernetwasdesignedtoservein
networkswithsporadic,occasionallyheavytraffic
requirements.
oEthernetVersion2.0wasjointlydevelopedby
DigitalEquipmentCorp.,IntelCorp.,andXerox
Corp.WhichcommonlyknownasDIX.Itis
compatiblewithIEEE802.3.
oTheIEEE802.3specificationwasdevelopedin
1980basedontheoriginalEthernettechnology.
21
EthernetHistory
o1970sALOHAo1980EthernetDIX
o1973Robertvl.O
Metclafe'sresearchato1982EthernetDIX
Xeroxv2.0
2.94Mbps,CSMA/
CDo1983IEEE802.3
o1976StarcomputerStandardApproved
defineda10Mbpso1995IEEE802.3|J
version
100Mbps
o1979DIXconsortium
o1980-83Standardso1998IEEE802.3z
Path1000Mbps
FromDIXto802.3o2002IEEE802.3ae
lOGbps
o2010IEEE802.ba:
40/100Gbps
22
Ethernetontheweb
o10Mbps
/ethernet/
10mbps.html
o100Mbps
olGbps
/
olOGbps
?http://www.lOgigabit-ethernet.com
olOOGbps
/
23
相關(guān)介質(zhì)
EthernetFamily
oEthernetoperateat10Mbpsover
coaxialcable
o100Mbps,knownasFastEthernet,
operatesat100Mbpsovertwisted-pair
cable,alsoonDpticalfiber
o1000Mbps,knownasGigabitEthernet,
thatoperatesat1000Mbps(1Gbps)
overopticalfiberandtwisted-paircable
o10GEthernetoperatesatlOGbpsover
opticalfiber
o100GEthernetoperatesatlOOGbps
overopticalfiber
24
EthernetMigration
olOMb/stolOOMb/s
Shrinkthecollisiondomain
Onlytworepeaters
olOOMb/stolGb/s
Extendcarriertoallowmeaningfulcollision
domain
Onlyonerepeater
olGb/stolOGb/s
MakelOGbEfullduplexonly,nocollision
domain
25
Namingconvention10Base^1
BASE-y數(shù)據(jù)率(M匕時)基帶或?qū)拵Ф巫畲箝L度(百米)
CharacteristicEthernetValueIEEE802.3Values
Datarate1010Base510Base2lOBaseTlOBaseFlOOBaseT
(Mbps)
10101010100
SignalingBasebandBasebandBasebandBasebandBasebandBaseband
method
Maximum5005001851002000100
segment
length(m)
Impedance50Q50Q50Q100Q100Q
MediaThickcoaxThickThinCoaxUTPFiber-opticUTP
coax
TopologyBusBusBusStarP-to-PBus
xBASE-y<datarateinMbpsxsignalingmethod><maximumsegmentlengthinhundredsofmeters義6
協(xié)議結(jié)構(gòu)
ProtocolArchitecture
oDefineslayers1and2specifications
Physicallayer(layer1)
oProvidestheelectrical,mechanicaland
Droceduralspecsforthetransmissionof
Ditsthroughacommunicationlink,
mediumorchannel
Datalinklayer(layer2)
oEnsureserrorcontrolandsynchronization
betweentwoentities
oIncludesMediumAccessControl(MAC)
andLogicalLinkControl(LLC)sub-layers
27
MAC接入控制
MediaAccessControl
oAddress
oCSMA/CD
oCollisioncontrol
oOperationmode
Half-duplex
Full-duplex
oDeviceimplementation
28
以太網(wǎng)地址
EthernetAddress
oGlobalunique
oAssignmentmanagement
byXerox,laterbyIEEE
o48bitlong
oVendorSection+Node
address
00:80:C8:8A:35:5F
oSingle-cast/Multicast/Broadcast
29
MAC子層的地址問題
oIEEE802標(biāo)準(zhǔn)為每個DTE規(guī)定了一個48位的全局地址,相
當(dāng)于站點(diǎn)的唯一標(biāo)識符,與其物理位置無關(guān)
oMAC地址字段可以采用兩種形式之一:
6B全球范圍,2B單位范圍
o地址塊:地址字段的前3個字節(jié)(高24位)由IEEE統(tǒng)一分
配給廠商,低24位由廠商分配;
o地址類型標(biāo)識:地址字段的第一字節(jié)的最低位I/G0??單
個站地址;1??組地址
o地址范圍標(biāo)識:地址字段的第一字節(jié)的最低第二位U/L0-
局部管理;1“全局管理
1146115
I/GU/L46位地址I/G15位地址
30
什么是廣播地址
Whatisabroadcastaddress?
oTheuniqueaddressthatidentifiesa
packetasappropriatetoall
receivingstations.
oExample
ff:ff:ff:ff:ff:ff
31
如何檢查MAC地址
HowtocheckMACaddress
oWin95/98/2000,WinNT,DOS,XP
c:\arp-a
c:\winipcfg-c:\ipconfig/all
oUNIX/Linux
ifconfig-a
oNovell
intheServerconsole
oSniffer
oRouter
showarp...
o
32
MAC類型
MACtypes
oThereare2MACprotocolsdefinedfor
.Ethernet
,Half-duplex
?Full-duplex
oHalf-duplexisthetraditionalformof
Ethernet
Datatransmissioninonedirectionatatime
UsesCSMA/CDprotocol
oFull-duplexbypassestheCSMA/CD
protocol
Full-duplexmodeallowstwostationsto
、、simultaneouslyexchangedataoverapointto
全雙工定義pointlinkthatprovidesindependenttransmit
andreceivepaths
33
CSMA/CD半雙工
CSMA/CD(Half-Duplex)
oAnystationonaCSMA/CDLANcanaccessthe
networkatanytime.
oBeforesendingdata,CSMA/CDstationslistenfor
trafficonthenetwork.
oAstationwantingtosenddatawaitsuntilitdetectsno
trafficbeforeittransmits.
oAfterapacketistransmitted,thestationlistenstothe
channelwhilethetransmittedpacketisintransitover
thecable.
oIfnocollisionisdetected,thepacketissuccessfully
transmitted.
oIfacollisionisdetectedduringtransmission,then
transmitabriefjammingsignaltoinformother
stationsofthecollision,andimmediatelycease
transmission.
34
CSMA/流
CSMA/CDFlow
Stationisready
tosend
Waitaccordingto
NewAttempt
BackoffStrategy
八
Transmitdata&CollisionDetectedTransmitJam
sensechannelSignal
INoCollisionDetected
TransmitComplete
J5
二進(jìn)制指數(shù)退避算法
TruncatedBinaryExponentialBackoff
Algorithm
oBinaryexponentialbackoffalgorithmwhen
collisionsoccur:
Iftwostationscollide,theneachstationwaits
either0or1slotbeforeattempting
retransmission
Ifasecondcollisionoccurs,thenthewaitingtime
israndomlychosenfrom0..3slots
Ifaftericollisions,waitingtimeisselected
randomlyfrom0to2L1slots
After10collisionstherandomintervalisfixedat
1023slots
After16collisions,thecontrollerreportsfailureto
thesender
36
Collision1
37
Collision2
□□
Stat沁nA
I1010101010
1010101010n
StationB
38
Collision3
StationB
39
Collision4
40
Collision5
41
Speedcalculation
ospeedoflightinavacuum
300,000,000meters/second
ospeedofelectricityinacopper
cable
200,000,000meters/second
olOMbpsEthernet:
(200,000,000m/s)/(10,000,000
bits/s)=20metersperbit
42
全雙工MAC類型
Full-duplexMACTypes
oBasedontheIEEE802.3xstandard,FD
MACtypebypassestheCSMA/CDprotocol
oFDmodeallowstwostationsto
simultaneouslyexchangedataovera
pointtopointlink
oAggregatethroughputofthelinkis
effectivelydoubled
FD100Mb/sstationprovides200Mb/sof
bandwidth
oFDoperationisrestrictedtopointtopoint
linksconnectingexactlytwostations
oUsedin1/10GbEonly.
43
EthernetandIEEE802.3Frame
Formats
FieldLength,
inBytesEthernet
866246-15004
PreambleDestinationSourceTypeDataFCS
AddressAddress
FieldLength,
inBytesIEEE802.3
7166246-15004
S
PreambleODestinationSourceLength802.2HeaderFCS
FAddressAddressandData
SOF=Start-of-FrameDelimiter
FCS=FrameCheckSequence
44
EthernetandIEEE802.3FrameFields
oPreamble--Alternatingpatternofonesand
zerosthattellsreceivingstationsthataframe
iscoining(EthernetorIEEE802.3),The
Ethernetframeincludesanadditionalbyte
thatistheequivalentoftheStartofFrame
(SOF)fieldspecifiedintheIEEE802.3frame.
oStart-of-Frame(SOF)--TheIEEE802.3
delimiterbyteendswithtwoconsecutive1
bits,whichservetosynchronizetheframe
receptionportionsofallstationsontheLAN.
SOFisexplicitlyspecifiedinEthernet.
45
EthernetandIEEE802.3FrameFields
(Cont')
oDestinationandSourceAddresses--
Thefirst3bytesoftheaddressesare
specifiedbytheIEEEonavendor-
dependentbasis.Thelast3bytesare
specifiedbytheEthernetorIEEE
802.3vendor.
oThesourceaddressisalwaysaunicast
(singlenode)address.
oThedestinationaddresscanbe
unicast,multicast(group),or
broadcast(allnodes).
46
EthernetandIEEE802.3FrameFields
(Conf)
oLength/Type
Type(Ethernet)--Specifiestheupper-layer
protocoltoreceivethedataafterEthernet
processingiscompleted.
Length(IEEE802.3)—Indicatesthenumberof
bytesofdatathatfollowthisfield.
oData(Ethernet)—Datacontainedinthe
frame.Afterphysicallayerandlinklayer
processingiscompleted,thisdataissentto
anupper-layerprotocol.Theupper-layer
protocolisidentifiedintheTypefield.
47
EthernetandIEEE802.3FrameFields
(Conf)___________________
oAlthoughEthernetVersion2doesnot
specifyanypadding(incontrastto
IEEE802.3),Ethernetexpectsatleast
46bytesofdata.
oData(IEEE802.3)--Datacontainedin
theframe.Afterphysicallayerandlink
layerprocessingiscomplete,thisdata
issenttoanupper-layerprotocol.The
upper-layerprotocolmustbedefined
withinthedataportionoftheframe,if
atall.
48
EthernetandIEEE802.3FrameFields
(Conf)
oIfdataintheframeisinsufficienttofill
theframetoitsminimuin64-byte
size,paddingbytesareinsertedto
ensureatleasta64-byteframe.
oFrameCheckSequence(FCS)—
Containsa4-bytecyclicredundancy
check(CRC)value.TheCRCiscreated
bythesendingdeviceandrecalculated
bythereceivingdevicetocheckfor
damagedframes.CRC定義
49
虛網(wǎng)標(biāo)記
VLANTagging
oEthernetframeformatextensionstosupport
VirtualLocalAreaNetwork(VLAN)Tagging
oTheVLANprotocol(802.lq)permitsinsertionof
anidentifier,or“tag”,intotheEthernetframe
format
oVLANTaggingprovidesvariousbenefits
Easingnetworkadministration
Allowingformationofworkgroups
Enhancingnetworksecurity
oThe4-byteVLANtagisinsertedbetweenthe
“Source”MACAddressfieldand“Length/Type”
field
50
Formatof:
802.3/802.1Q
802.3DestSourceTypeDataFCS
「Maxi518]Addr(6)Addr(6)(2)(Max1496;(4)
802.1QDestSourceVLANVLANTypeDataFCS
[Maxl518]Addr(6)Addr(6)Type(2)ID⑵(2)(Max1496:(4)|
51
混合模式
Promiscuousmode
oPromiscuousmodeisaconditionwherethe
networkinterfacecontrollerwillpassallframes,
regardlessofdestinationaddress,uptothehigher
levelnetworklayers.Normallythenetwork
controllerwillonlypassupframesthathave
thatdevice'sdestinationaddress.However,when
putinpromiscuousmode,allframesarepassedon
upthenetworkstackregardlessofdestination
address.Promiscuousmodeisusuallyusedby
networkmonitoringtoolsandtransparentbridges
(and,frequently,bynetworkcrackerstryingto
snatchpasswords,orotherdatathey'renormally
notabletosee,offthewire).
52
Reference
o/ethernet/
descript-10quickref.html
o/ethernet/
100mbps.html
o/ethernet/
o/univercd/cc/td/
doc/cisintwk/ito_doc/ethernet.htm
o/consortiums/fe/
o/research/
ge.html
53
100MbpsEthernet
ApplicationSoftware
andUpper-layerProtocols
TCP/IP
Carddriver
802.3MediaAccessControl
Sublayer
100Base-T
PhysicalLayerlOOBaseTXlOOBaseFX100BaseT4
54
10M和100M以太網(wǎng)區(qū)別
Differencesin10/1OOMEthernet
oSpeed
100Mbps
oCoding
?MLT3
oAuto-Negotiation
anoptionalpartoftheEthernetstandardthat
makesitpossiblefordevicestoexchange
informationabouttheirabilitiesoveralink
segment.
allowsthedevicestoperformautomatic
configurationtoachievethebestpossible
modeofoperationoveralink.
oCableSpecification
55
FLPS百兆以太網(wǎng)快速鏈路脈沖
FLPs-WOBaseTastLinkulses
olOOBaseTusespulses,calledfastlink
pulses(FLPs),tocheckthelinkintegrity
betweenthehubandthelOOBaseT
device.
oFLPsarebackwardcompatiblewith
lOBaseTnormallinkpulses(NLPs).But
FLPscontainmoreinformationthanNLPs,
andareusedintheauto-negotiation
processbetweenahubandadeviceona
lOOBaseTnetwork.
56
主要設(shè)備
MajorDevices
oNetworkInterface
Card
oTransceiver
oRepeater
oBridge____
oSwitch
__1
r)7
千兆以太網(wǎng)概述
GigabitEthernetOverview
oGigabitEthernetisanextensionoftheIEEE802.3
Ethernetstandard-802.3z.GigabitEthernetoffers
1000Mbpsofrawdatabandwidthwhilemaintaining
compatibilitywithEthernetandFastEthernetnetwork
devices.
Newfull-duplexoperatingmodesforswitch-to-switch
andswitch-to-end-stationconnections
Half-duplexoperatingmodesforsharedconnections
usingrepeatersandCSMA/CD
Usesthesameframeformat,framesize,and
managementobjectsusedinexistingIEEE802.3
networks
Initiallyoperateoverfiberopticcabling,butwillbe
implementedoverCategory5unshieldedtwisted-pair
(UTP)as802.3ab.
58
GigabitEthernet
'w|CaptureI<Unkno
59
到千兆以太網(wǎng)的過渡
MigrationtoGigabitEthernet
oUpgradeswitch-to-switch
links--1000Mbps
oUpgradeswitch-to-server
links--1000Mbps
oUpgradeaFastEthernetbackbone
oAllowsserverstobeconnecteddirectly
tothebackbonewithGigabitEthernet
NICs
oUpgradehighperformancedesktops
60
IEEE802.3Ethernet
IEEE802.3
LLCProtocolStackofGE
IEEE802.3
CSMA/CD
aIEEE802.2LLC
IEEE802.3
PhysicalLayer
CSMA/CDFullDuplex
MediaAccessControl(MAC)
ANSIX3T11FibreChannel
8B/10B
FC-4UpperLayerEncode/Decode
Mapping
FC-3CommonSerializer/Deserializer
Services
FC-2SignalingConnector
FC-1
Encode/DecodeIEEE802.3zGigabitEthernet
FC-0Interface
andMedia61
8B/10BEncoder
汽TM⑷DataByte
LESOFEIGHT書ITCODEGROUPS
ActualByteRD?RD+Effecton
BeingEncodingEncocfingRDafter
EncodedValueValue
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