現(xiàn)代通信網(wǎng)絡(luò)課件

現(xiàn)代通信網(wǎng)絡(luò)

ModernTelecommunicationNetworkLecture3(CS)電路交換與軟交換北郵軟件學(xué)院：陳候武Chenhouwu@電話：現(xiàn)代通信網(wǎng)絡(luò)

ModernTelecommunicatio1CommunicationNetworks【通信網(wǎng)絡(luò)的分類】CommunicationNetworkSwitched

CommunicationNetworkVirtualCircuitNetwork:MPLSBroadcast

CommunicationNetwork廣播，電視，衛(wèi)星PacketSwitch(PS)-分組交換DatagramNetwork:Internet:IP因特網(wǎng)Circuit-Switched(CS)-電話CommunicationNetworks【通信網(wǎng)絡(luò)的分2通信業(yè)務(wù)網(wǎng)(ServiceNetwork)：分類：通信業(yè)務(wù)網(wǎng)(ServiceNetwork)：分類：3SwitchedNetwork：【通信交換網(wǎng)絡(luò)】SwitchedNetwork：【通信交換網(wǎng)絡(luò)】4NodeSwitching（節(jié)點交換）Anode(switch)inacircuitswitchingnetworkincominglinksoutgoinglinksNodeNodeSwitching（節(jié)點交換）Anode(5Nodes

【交換節(jié)點】Nodesmayconnecttoothernodesonly,ortostationsandothernodesNodetonodelinksusuallymultiplexed【復(fù)用】NetworkisusuallypartiallyconnectedSomeredundantconnections【冗余連接

】aredesirableforreliabilityTwodifferentswitchingtechnologiesCircuitswitching【電路交換】Packetswitching【分組交換】Nodes【交換節(jié)點】Nodesmayconnect6CS:CircuitSwitch電路交換【Overview】CS:CircuitSwitch7CS:CircuitSwitching【電路交換】Dedicatedcommunicationpathbetweentwostations【專用/獨(dú)享的通信通道】Threephases【呼叫建立：3個階段】EstablishTransferDisconnectMusthaveswitchingcapacityandchannelcapacitytoestablishconnectionMusthaveintelligencetoworkoutrouting必須具有智能以對呼叫進(jìn)行選路CS:CircuitSwitching【電路交換】De8CircuitSwitching-ApplicationsInefficientChannelcapacitydedicatedfordurationofconnectionIfnodata,capacitywastedSetup(connection)takestimeOnceconnected,transferistransparentDevelopedforvoicetraffic(phone:電話網(wǎng))CircuitSwitching-Applicatio9CS：PSTN–

網(wǎng)絡(luò)結(jié)構(gòu)PSTN–PublicSwitchedTelephoneNetworkUsesdigitaltrunksbetweenCentralOfficeswitches(CO)UsesanaloglinefromphonestoCODigitalTrunks數(shù)字中繼AnaloglineCentralOfficeCentralOfficeCS：PSTN–網(wǎng)絡(luò)結(jié)構(gòu)PSTN–PublicSw10PSTN:PublicCircuitSwitchedNetworkPSTN:PublicCircuitSwitched11CS:Components【網(wǎng)絡(luò)組成】Subscriber【用戶：電話】Devicesattachedtonetwork

Subscriberline【用戶連線】LocalLoop【本地環(huán)路】Subscriberloop【用戶環(huán)路】ConnectiontonetworkFewkmuptofewtensofkmExchange/Switch【交換機(jī)】SwitchingcentersEndoffice-supportssubscribersTrunks【中繼線】BranchesbetweenexchangesMultiplexed【復(fù)用】CS:Components【網(wǎng)絡(luò)組成】Subscribe12LegacyDigitalCircuitSwitchCentralizedIntelligenceProprietaryCodeProprietaryservicedeploymentVeryexpensiveLegacyDigitalCircuitSwitchC13CircuitSwitchElements【電路交換組成】CircuitSwitchElements【電路交換組14CircuitSwitchingConceptsDigitalSwitch【數(shù)字交換】ProvidetransparentsignalpathbetweendevicesNetworkInterface【網(wǎng)絡(luò)接口】ControlUnit【控制單元】EstablishconnectionsGenerallyondemandHandleandacknowledgerequestsDetermineifdestinationisfreeconstructpathMaintainconnectionDisconnectCircuitSwitchingConceptsDigi15NodeswitchingSystem:NodeswitchingSystem:16CS：SPC:電話數(shù)字程控交換機(jī)–模塊CS：SPC:電話數(shù)字程控交換機(jī)–模塊17CS:CirtuitSwitch

【SwitchFabric：交換矩陣】現(xiàn)代通信網(wǎng)絡(luò)課件18SwitchFabric:MxNSwitchFabric:MxN19SwitchFabric:MathgraphpresentationAinputmaysetuponeconnection(1,3,6,7),multipleconnections(4),ornoconnection(2,5,8).SwitchFabric:Mathgraphpres20SwitchFabric:數(shù)學(xué)模型Inputset:T={0,1,2,…,M-1}Outputset:R={0,1,2,…,N-1}Definition:t∈Tandr∈Rt，Rt∈R，then:c=|t,Rt|isaconnection.tisstartpointoftheconnection,r∈Rtistheendpoint.ifr∈Rt,Rtcontainsonlyoneitem,thisconnectionispointtopoint.ifr∈Rt,Rtcontainsmorethanoneitem,thisconnectionispointtomulti-point.Multicast:Rt≠R;Broadcast:Rt=Rconnectionsetinswitchfabric:C=|c0,c1,c2,…|SwitchFabric:數(shù)學(xué)模型Inputset:21SwitchFabric:連接函數(shù)連接函數(shù):inputlink:x(0<=x<=M-1)Outputlinkf(x)(0<=f(x)<=N-1).

例如：連接函數(shù):δ(x2,x1,x0)=x1,x0,x2δ(000)=000,δ(001)=010,δ(010)=100,δ(111)=111SwitchFabric:連接函數(shù)連接函數(shù):inpu22SwitchingFabric:TimeDivisionTime-slotswitchingisadevice,whichbuffersmincomingtime-slots,arrangesnewtransmitorderandtransmitsntime-slotsUsedinPacketswitchandATMaswellasdigitaltelephoneswitchSwitchingFabric:TimeDivisio23SwitchingFabric:SpaceDivisionSwitchingFabric:SpaceDivisi24Time/SpaceDivisionMultiplexing

TIMESWITCHTIMESWITCHTIMESWITCHTIMESWITCHTIMESWITCHTIMESWITCHSPACESWITCHTime/SpaceDivisionMultiplexi25CS：BlockingorNon-blockingBlocking【阻塞】AnetworkisunabletoconnectstationsbecauseallpathsareinuseAblockingnetworkallowsthis【網(wǎng)絡(luò)允許Blocking】UsedonvoicesystemsShortdurationcallsNon-blocking【無阻塞】Permitsallstationstoconnect(inpairs)atonceUsedforsomedataconnectionsCS：BlockingorNon-blockingBlo26SwitchingFabric:Blocking如果：I0正在連續(xù)到O0,問：I1可以連接到O0orO1???結(jié)果：內(nèi)部阻塞SwitchingFabric:Blocking如果：27解決方案：MultistageSwitchReducednumberofcross

pointsMorethanonepaththroughnetwork

IncreasedreliabilityMorecomplexcontrolMaybeblocking解決方案：MultistageSwitchReduced28解決方案：兩級交換矩陣解決方案：兩級交換矩陣29解決方案：ThreeStageSwitchxxxx解決方案：ThreeStageSwitchxxxx30CS：TST交換矩陣-實例：TST-TimeswitchandSpaceswitch(1)T接線器:Auserinfo.Occupyatimeslot8bitscode.CS：TST交換矩陣-實例：TST-Timesw31（3）TST接線器－512x512TimeSlots（3）TST接線器－512x512TimeSlo32CS:電路交換【PSTN:TrunkMultiplexing】現(xiàn)代通信網(wǎng)絡(luò)課件33CO1–CO2:TruckMultiplexingCO1–CO2:TruckMultiplexing34Mux….….….….….11111222….64kb/svoicechannelt4t3t2t12Mb/soutputsignal同步時分復(fù)用：SynchronousTDMMux….….….….….11111222….64kb/s35E1:2Mb/sframestructureAllTimeslotscontain8bitwords(PCM,Data,Subrate,nx64kb/s)NetworkSignaling-CASorCCS0123…14151617…30310…1frame-256bits-125msFrameAlignmentWord3.9usNetworkSignalingChannels1to15Channels16to30E1:2Mb/sframestructureAllT36

MUXMUXMUXMUXMUX1234

1234

E1E1E1E1E2E2E2E2

E52.0488.44834.368139.264561.480MbpsMbpsMbpsMbpsMbps

CH2

CH1

CH32E31E32E33E34

E41E42E43E44ITU-TE1DIGITALMULTIPLEXINGHIERARCHYE1 E2E3E4E51E1E52.04837ANSI：T1-T-carriersystem1.544MEachframecarriesonesample(8bits)foreach24channels,plusoneframingbit=193bits193*8000(samples/sec)=1.544Mbit/sec=T-1Channel1Channel2Channel3Channel24…Channel1Channel2Channel3Channel24…FramingBit1D4FrameTDMANSI：T1-T-carriersystem1.538ANSI:T1/DS1FrameStructure-1.544Mbps

Every8thbitusedforsignalinginefficient01221226…2023…1frame-193bits-24channelsBit8-reservedforsignalingFramingbit34501Bits1-7PayloadANSI:T1/DS1FrameStructure39ANSI:DIGITALMULTIPLEXINGHIERARCHYT1 T2 T3T4T5

MUXMUXMUXMUXMUX12T313T324T335T346T357T36123412

T1T1T1T1T2T2T2T2T2T2T2

T4T4T5

CH1CH2CH2424VF1.5446.31244.736274.176560.160MbpsMbpsMbpsMbpsMbpsANSI:DIGITALMULTIPLEXING40現(xiàn)代通信網(wǎng)絡(luò)課件41StatisticalTDM【統(tǒng)計時分復(fù)用】InSynchronousTDMmanyslotsarewastedStatisticalTDMallocatestimeslotsdynamicallybasedondemandMultiplexerscansinputlinesandcollectsdatauntilframefullDatarateonlinelowerthanaggregateratesofinputlinesStatisticalTDM【統(tǒng)計時分復(fù)用】InSyn42StatisticalTDMFrameFormatsStatisticalTDMFrameFormats43StatisticalTDMvSynchronousTDM

StatisticsTDMdividesadatalinkintosomelogicsub-channelStatisticalTDMvSynchronous44StatisticalTDMvSynchronousTDM：FormatsStatisticalTDMvSynchronous45StatisticalTDM舉例：HDLCHDLC：HighLevelDataLinkControlSynchronoustransmissionAlltransmissionsinframesSingleframeformatforalldataandcontrolexchangesStatisticalTDM舉例：HDLCHDLC：H46HDLC：FrameStructureFlagAddressControlInformationFCSFlag8bits8extendable8/16variable816/32trailerFrameCheckSumHDLC：FrameStructureFlagAddre47HDLC：AddressFieldIdentifiessecondarystationthatsentorwillreceiveframeUsually8bitslongMaybeextendedtomultiplesof7bitsLSBofeachoctetindicatesthatitisthelastoctet(1)ornot(0)Allones(11111111)isbroadcastHDLC：AddressFieldIdentifiess48CS:電路交換【PSTN:Signaling信令】與【CallControl：呼叫控制】CS:電路交換49CS:PSTN控制信令與呼叫控制–各階段Eachconversationrequiresachannelswitchedthroughoutthenetwork呼叫請求：Callrequest；呼叫建立：Callestablished;呼叫接收1.Callisrequested3.Channelisestablished2.CallisacceptedCS:PSTN控制信令與呼叫控制–各階段Each50PSTNCS:PSTN–

電話號碼編碼方案3digitsareacode【區(qū)域碼】+3digitsofficecode【局碼】+4digitsphone【本局隨機(jī)碼】EachLocalExchangeCarrierswitch(LEC：本地交換局)areassignedablockofatleast10,000numbersTheInter-ExchangeCarrier(IXC：匯接局)switchesareresponsiblefortransmittinglongdistanceIXC212LEC5554210(212)5554210PSTNCS:PSTN–電話號碼編碼方案3digit51CS:PSTN–CallRouting-1InternationalNumberingPlan–E.164【國際電話號碼方案】useprefix-baseddialing4085644555212PSTN1+212+555+5644SS7CS:PSTN–CallRouting-1Int52CS:PSTN–CallRouting-2ThefirstLEC【本地交換機(jī)】receivesacall,seeing‘1’asthefirstdigitandthenpassesthecallontotheIXCswitch.TheIXCthenroutesthecall,viaSS7,totheremoteIXCresponsiblefor‘212’.【遠(yuǎn)端的212中繼局】The‘212’IXClooksattheofficecodeandpassesitontothe‘555’LECswitch.【515本地局】The‘555’LECswitchthenchecksthestationcodeandsignalstheappropriatephoneCS:PSTN–CallRouting-2The53Signaling:ControlFunctions【控制功能】AudiblecommunicationwithsubscriberTransmissionofdialednumberCallcannotbecompletedindicationCallendedindicationSignaltoringphoneBillinginfoEquipmentandtrunkstatusinfoDiagnosticinfoControlofspecialistequipmentSignaling:ControlFunctions【54PSTN：用戶信令Usesloop-startsignaling【環(huán)路信令】Indicatesifthephoneison-hookoroff-hook,orgeneratesring-toneonphone.Closescircuitwhenphoneisoff-hookUsestwowires,tipandringTipFXSRingPSTN：用戶信令Usesloop-startsigna55SwitchtoSwitchSignaling：【中繼信令】SubscribersconnectedtodifferentswitchesOriginatingswitchseizesinterswitchtrunkSendoffhooksignalontrunk,requestingdigitregisterattargetswitch(foraddress)Terminatingswitchsendsoffhookfollowedbyonhook(wink)toshowregisterreadyOriginatingswitchsendsaddressSwitchtoSwitchSignaling：【中繼56中繼信令：基本呼叫流程：中繼信令：基本呼叫流程：57中繼信令：呼叫控制：FSM–FiniteStateMachine

(有限狀態(tài)機(jī)–

主叫方

)掛機(jī)狀態(tài)摘機(jī)狀態(tài)通話狀態(tài)撥號狀態(tài)忙音狀態(tài)振鈴狀態(tài)請求呼叫狀態(tài)回鈴狀態(tài)摘機(jī)撥號撥號正確撥號撥號錯誤被叫振鈴被叫摘機(jī)被叫用戶忙被叫無應(yīng)答被叫掛機(jī)主叫掛機(jī)收到新的呼叫摘機(jī)中繼信令：呼叫控制：FSM–FiniteStateM58PSTN:SignalingMethods【中繼信令分類】CAS–ChannelAssociatedSignaling【隨路信令】SignalingassociatedwitheachchannelhasfixedplacementwithinframeTraditionalT-1andE-1forvoiceusesCASCCS–CommonChannelSignaling【共路信令】Signalingpassedviamessagingprotocol,out-of-bandsignalingCancarryawidevarietyofmessages,e.g.Caller-IDetcISDNusesaCCS-basedprotocol–Q.931Q.SIGwhichistypicallyusedforPBX-to-PBXconnectivity,andisavariantofQ.931,isCCD-basedSS7istheCCS-basedprotocolusedinthePSTN,i.e.betweenCOsPSTN:SignalingMethods【中繼信令分類59Drawbacks【缺點】ofInCASLimitedtransferrateDelaybetweenenteringaddress(dialing)andconnectionOvercomebyuseofcommonchannelsignalingDrawbacks【缺點】ofInCASLimited60CASv.CCSCASv.CCS61SS7：SignalingSystemNumber7SS7：CommonchannelsignalingschemeISDNOptimizedfor64kdigitalchannelnetworkCallcontrol,remotecontrol,managementandmaintenanceReliablemeansoftransferofinfoinsequenceWilloperateoveranalogandbelow64kPointtopointterrestrialandsatellitelinksSS7：SignalingSystemNumber7S62PSTN–SS7/SignalingSystem7SS7messagesareexchangedbetweennetworkelementsonbi-directionalchannels(typicallyT1lines)calledsignalinglinks.TrunkLinesSSP(CO)SSP(CO)STPSS7STPT-1T-1PSTN–SS7/SignalingSystem763PSTN–SS7SignalingPoints

SS7networkiscriticaltocallprocessing,SCPsandSTPsareusuallydeployedinmatedpairconfigurationsinseparatephysicallocationstoensurenetwork-wideserviceintheeventofanisolatedfailure.Linksbetweensignalingpointsarealsoprovisionedinpairs.Trafficissharedacrossalllinksinthelinkset.Ifoneofthelinksfails,thesignalingtrafficisreroutedoveranotherlinkinthelinkset.SS7LinksSTPSTPSSPSSPSCPSCPSS7LinksTrunkLinksPSTN–SS7SignalingPointsS64SS7：網(wǎng)元功能SSP(ServiceSwitchingPoint)

SSPsareswitchesthatoriginate,terminate,ortandemcalls.AnSSPsendssignalingmessagestootherSSPstosetup,manage,andreleasevoicecircuitsrequiredtocompleteacall.AnSSPmayalsosendaquerymessagetoaSCPtodeterminehowtorouteacall.【智能網(wǎng)功能】ThefunctionalityoftheSSPisusuallyintegratedintotheCO(CentralOfficeswitch：終端局).STP(SignalTransferPoint)【信號轉(zhuǎn)接點】NetworktrafficbetweensignalingpointsmayberoutedviaapacketswitchcalledanSTP.AnSTProuteseachincomingmessagetoanoutgoingsignalinglinkbasedonroutinginformationcontainedintheSS7message.AnSTPcanalsoactasa"firewall"toscreenSS7messagesexchangedwithothernetworks.SCP(ServiceControlPoint)【信號控制點】AnSCPisacentralizeddatabasethattellsanSSPhowtorouteacall(e.g.,atoll-free1-800/888call).ItsendsaresponsetotheoriginatingSSPcontainingtheroutingnumber(s)associatedwiththedialednumber.SS7：網(wǎng)元功能SSP(ServiceSwitching65SS7：信令功能SS7在移動網(wǎng)絡(luò)中漫游功能的應(yīng)用SS7：信令功能SS7在移動網(wǎng)絡(luò)中漫游功能的應(yīng)用66CS:電路交換【PSTN:電話網(wǎng)組網(wǎng)原理】現(xiàn)代通信網(wǎng)絡(luò)課件67CS：AT&TTelephonyHierarchyClass5Class4Class3Class2Class1CS：AT&TTelephonyHierarchyCla68CS：TelephoneNetworkModelCS：TelephoneNetworkModel69CS：傳統(tǒng)電話網(wǎng)分層結(jié)構(gòu)的問題：層次太多匯接層次（轉(zhuǎn)接交換機(jī)）過多導(dǎo)致呼叫建立延遲傳輸損失。降低了呼叫接通率降低了系統(tǒng)的可靠性一個轉(zhuǎn)接交換機(jī)出問題，將阻塞整個網(wǎng)絡(luò)網(wǎng)絡(luò)管理復(fù)雜CS：傳統(tǒng)電話網(wǎng)分層結(jié)構(gòu)的問題：層次太多70我國電話網(wǎng)：Twolevelsoftransitnetwork

長途網(wǎng)絡(luò)結(jié)構(gòu)正在從4層演進(jìn)到2層（扁平化）DC1(directconnection1)–高層（省間層）DC2(directconnection2)–低層（省內(nèi)層）我國電話網(wǎng)：Twolevelsoftransitne71CS：局間中繼聯(lián)系方式DC1–省際：互聯(lián)至其他省；省內(nèi)：星型連接至DC2DC2–同層DC2之間互聯(lián)，或者部分互聯(lián)，也可直連至其他省CS：局間中繼聯(lián)系方式DC1–省際：互聯(lián)至其他??；省內(nèi)：72CS：本地網(wǎng)互聯(lián)方式Alllocalswitchesareconnectedeachotherbydirecttrucks.Suitabletolesslocalswitchesinthesamearea.CS：本地網(wǎng)互聯(lián)方式Alllocalswitchesa73CS:電話網(wǎng)的路由選擇高效直達(dá)路由(H):永遠(yuǎn)是首選低呼損直達(dá)路由(L):最后選擇用戶A–呼叫–用戶B：A1-B1,A1-B2-B1,A1-A2-B2-B1,A1-A2-B3-B2-B1,A1-A2-A3-B3-B2-B1CS:電話網(wǎng)的路由選擇高效直達(dá)路由(H):永遠(yuǎn)是首選74CS：Routing【電路交換：路由定義】ManyconnectionswillneedpathsthroughmorethanoneswitchNeedtofindarouteEfficiencyResilience【彈性】PublictelephoneswitchesareatreestructureStaticroutingusesthesameapproachallthetime【靜態(tài)路由】Dynamicroutingallowsforchangesinroutingdependingontraffic【動態(tài)路由】UsesapeerstructurefornodesCS：Routing【電路交換：路由定義】Manyco75CS：AlternateRouting【迂回路由】PossibleroutesbetweenendofficespredefinedOriginatingswitchselectsappropriaterouteRouteslistedinpreferenceorderDifferentsetsofroutesmaybeusedatdifferenttimesCS：AlternateRouting【迂回路由】Pos76CS：Alternate

Routing

DiagramCS：AlternateRoutingDiagram77CS:電路交換【SoftSwitch:軟交換】現(xiàn)代通信網(wǎng)絡(luò)課件78CS存在問題：解決方案SoftswitchCS存在問題：解決方案Softswitch79Soft-switch：優(yōu)點Generalpurpose:computerrunningsoftwaretomakeitasmartphoneswitchLowercostsGreaterfunctionalityPacketizingofdigitizedvoicedataAllowingvoiceoverIPMostcomplexpartoftelephonenetworkswitchis【softwarecontrollingcallprocess】CallroutingCallprocessinglogicTypicallyrunningonproprietaryprocessorSeparatecallprocessingfromhardwarefunctionofswitchPhysicalswitchingdonebymediagatewayCallprocessingdonebymediagatewaycontroller【softswitch】Soft-switch：優(yōu)點Generalpurpose80TraditionalCircuitSwitchingTraditionalCircuitSwitching81CS：Softswitch

【軟交換結(jié)構(gòu)】MediaGatewayController【媒體網(wǎng)關(guān)控制器】=Softswitch：軟交換CS：Softswitch【軟交換結(jié)構(gòu)】MediaGat82CS：軟交換系統(tǒng)與傳統(tǒng)設(shè)備區(qū)別

電路交換模型呼叫控制SS7

LineCardTrunkCardTimeSlot交換TDMTDM管理系統(tǒng)計費(fèi)系統(tǒng)IPATM軟交換SS7MGMGIPATMH.248/MGCPH.248/MGCP軟交換模型TDMTDM分組網(wǎng)擴(kuò)展業(yè)務(wù)管理系統(tǒng)計費(fèi)系統(tǒng)核心變化將傳統(tǒng)交換機(jī)的功能模塊分離成為獨(dú)立的網(wǎng)絡(luò)部件，各個部件可以按相應(yīng)的功能劃分各自獨(dú)立發(fā)展。部件間的協(xié)議接口基于相應(yīng)的標(biāo)準(zhǔn),有利于實現(xiàn)各種異構(gòu)網(wǎng)的互通。CS：軟交換系統(tǒng)與傳統(tǒng)設(shè)備區(qū)別電路交換模型呼叫控制83CS：傳統(tǒng)PSTN網(wǎng)絡(luò)存在問題傳統(tǒng)網(wǎng)絡(luò)的僅支持單業(yè)務(wù)(語音)交換能力成為發(fā)展的最大瓶頸,低層交換能力支持并約束了高層能力;傳統(tǒng)網(wǎng)絡(luò)業(yè)務(wù)控制對象和業(yè)務(wù)應(yīng)用單元被封閉在業(yè)務(wù)交換網(wǎng)內(nèi),同時用戶接口和網(wǎng)絡(luò)接口的不同使用戶的業(yè)務(wù)能力受限;CS：傳統(tǒng)PSTN網(wǎng)絡(luò)存在問題傳統(tǒng)網(wǎng)絡(luò)的僅支持單業(yè)務(wù)(語音)84CS:Softswitch:PSTN-IPArchSS7SignallingGatewayPSTNTrunksMediaGateway(Trunking)PSTNOriginatingorTandemSwitch(es)SS7NetworkMediaGatewayControllerMediaGateway(Trunking)RTP/UDP/IPStream{Megaco}SS7SignallingGateway{Megaco}MediaGatewayControllerPSTNTrunksVoIPTerminalsPSTNOriginatingorTandemSwitch(es)SS7Network{M3UA/SCTP}{SS7}{SS7}{TDM}{TDM}{M3UA/SCTP}{SIP-T}CS:Softswitch:PSTN-IPArch85CS：軟交換結(jié)構(gòu)–網(wǎng)元組成MediaGatewayController（MGC）：Softswitch:SignalingGateway【信令網(wǎng)關(guān)】MediaGateway【媒體網(wǎng)關(guān)】TrunkinggatewayLineGatewayResidentialGateway軟交換的新業(yè)務(wù)成本僅為PSTN的【五分之一】。開發(fā)周期為PSTN的【十分之一】。占地是傳統(tǒng)電路交換機(jī)的十分之一。CS：軟交換結(jié)構(gòu)–網(wǎng)元組成MediaGatewayC86CS：MGC–媒體網(wǎng)關(guān)控制器的功能ContainsallcallcontrolintelligenceImplementscalllevelfeatures(forward,transfer,conference,hold,…)掛機(jī)狀態(tài)摘機(jī)狀態(tài)通話狀態(tài)撥號狀態(tài)忙音狀態(tài)振鈴狀態(tài)請求呼叫狀態(tài)回鈴狀態(tài)摘機(jī)撥號撥號正確撥號撥號錯誤被叫振鈴被叫摘機(jī)被叫用戶忙被叫無應(yīng)答被叫掛機(jī)主叫掛機(jī)收到新的呼叫摘機(jī)

CS：MGC–媒體網(wǎng)關(guān)控制器的功能Containsal87Master/slavecontrolofMGsbyMGCs

ConnectioncontrolDevicecontrolandconfiguration軟交換機(jī)【MGC】控制各種網(wǎng)關(guān)協(xié)議：

Megaco協(xié)議（當(dāng)前使用）

MGCP協(xié)議（過去使用）CS：MGC–媒體網(wǎng)關(guān)控制器協(xié)議Master/slavecontrolofMGs88Endpoint(eg.H.323Gateway,Terminal,MCU)

GatewayFunction(eg.H.323Gateway,Terminal,MCU)

CallAgentMediaGatewayControllerSignallingGatewayPSTN,ATM,etctrunkslinesSS7etcSigtranAnalogMediaGatewayPSTNtrunkingMediaGatewayPSTNlineMediaGatewayIPPhoneMediaGatewayMegacoScopeCS:軟交換系統(tǒng)組成與功能

MegacoProtocolCallcontrol(eg.H.323,SIP…)EndpointGatewayFunctionCallA89H.248IP(orATM)NetworkPBX/COPBX/COMediaGWControllerMediaGatewayDevicecontrolDevicecontrolIPPhoneMediaGatewayTelephone/ResidentialMediaGatewayPSTNtrunkingMediaGatewayPSTNlineMediaGatewayPBXMediaGatewayMediaGateway【媒體網(wǎng)關(guān)】:功能與分類ConnectionanddevicecontrolNocallprocessing,nocallmodelService-independentH.248IP(orATM)NetworkPBX/CO90CS:SignalingGateway【信令網(wǎng)關(guān)】：功能SignalingGatewaysprovideinteractionbetweentheSS7networkandMediaGatewayControllers.ConvertSS7toIPpacketsConvertIPtoSS7packetsSignalingtransport(SS7,SIP-T,Q.931…)ExtremelysecureExtremelyfaulttolerantCS:SignalingGateway【信令網(wǎng)關(guān)】：功能91MediaGWControllerTrunkGatewayMegaco/H.248VirtualSwitchSigtransSIP,H.323MediaGatewaySignallingGatewayPBXD-channelB-channelsPRIVirtualSwitchRTPSigtransSignalingGatewaySignalingGatewaySS7COSigtransSigtransTheInternetSS7NetworkCS:SignalingGateway【信令網(wǎng)關(guān)】-2MediaGWTrunkGatewayMegaco/V92Softswitch:MGC之間中繼信令SIP–SessionInitialProtocol在Softswitch網(wǎng)絡(luò)，我們需要一個中繼信令取代SS7SIP信令是最佳選擇Softswitch:MGC之間中繼信令SIP–Se93SS7Architecture【專用網(wǎng)絡(luò)：無法共享】SS7Architecture【專用網(wǎng)絡(luò)：無法共享】94SS7：ISUPCallEstablishment/ReleaseSS7：ISUPCallEstablishment/Re95SIPProtocol【基于IP網(wǎng)絡(luò)文本信令】SIPAudioCodecG.711G.723G.729VideoCodecH.261H.263RTPRTCPLANInterfaceTCPIPUDPSIPProtocol【基于IP網(wǎng)絡(luò)文本信令】SIPAu96SIPArchitectureAsignalingprotocolThesetup,modification,andtear-downofmultimediasessionsSIP+SDPDescribethesessioncharacteristicstopotentialsessionparticipantsSeparatesignalingandmediastreamsSignalingmaypassviaoneormoreproxyorredirectserversMediastreamtakesamoredirectpath.SIPArchitectureAsignalingp97SIPCallSignalingMedia(UDP)RTPStreamRTCPStreamSIPEndpointSIP+SDP(TCPorUDP)InviteRTPStreamSIPGatewayAssumesEndpoints(Clients)knoweachother’sIPaddressesSignalingPlaneBearerPlane200OKAck180RingingSIPCallSignalingMedia(UDP)R98軟交換（Softswitch）

在3G移動網(wǎng)絡(luò)中的應(yīng)用案例軟交換（Softswitch）

在3G移動網(wǎng)絡(luò)中的應(yīng)用案例99R4與R99核心網(wǎng)絡(luò)的差異MSCSCPHLRMSCRANRANRANTDMMSCServerSCPHLRRANRANRANTDM/ATM/IPMGWMGWMSCServerTUP/ISUP/BICCTUP/ISUPR99R4H.248H.248MAPOverTDMMAPOverTDM/IPCAPOverTDMCAPOverTDM/IPR4與R99核心網(wǎng)絡(luò)的差異MSCSCPHLRMSCRANRA100R5:GfGiIuGiMrGiMsGiRUuMGWGnGcTEMTUTRANGrSGSNGGSNEIRMGCFR-SGW*)MRFMultimediaIPNetworksPSTN/Legacy/ExternalApplications&Services*)MmMwLegacymobileNetworkMcCxAlternativeAccessNetworkMhCSCFCSCFMgT-SGW*)T-SGW*)HSS*)HSS*)Applications&Services*)MSCserverGMSCserverMcMcDCSCPCAPMGWNbNcIuIuR-SGW*)MhCAPCAPIPMultimediaDomain(multimediabySIP,IETFRFC2543)CSDomain(multimediabyITUH.324M)PSDomainCSCFUMTSRelease5:NetworkReferenceModelR5:GfGiIuGiMrGiMsGiRUuMGWGnGcT101Softswitch:分布式組網(wǎng)、設(shè)備獨(dú)立升級軟交換機(jī)將傳統(tǒng)交換機(jī)的功能模塊分離成為獨(dú)立的網(wǎng)絡(luò)部件，各個部件可以按相應(yīng)的功能劃分，各自獨(dú)立發(fā)展。部件間的協(xié)議接口基于相應(yīng)的標(biāo)準(zhǔn)，有利于實現(xiàn)各種異構(gòu)網(wǎng)的互通。媒體網(wǎng)關(guān)可實現(xiàn)拉遠(yuǎn)，與軟交換機(jī)可分開放置，使得它們各自可以獨(dú)立地進(jìn)行工程實施、擴(kuò)容和布局。由于業(yè)務(wù)升級遠(yuǎn)多于媒體交換能力升級，而采用軟交換后，軟交換機(jī)的數(shù)量遠(yuǎn)小于媒體網(wǎng)關(guān)的數(shù)量，這將帶來大量軟件升級費(fèi)用的節(jié)省。Softswitch:分布式組網(wǎng)、設(shè)備獨(dú)立升級軟交換機(jī)將102分布式組網(wǎng)、設(shè)備獨(dú)立升級(2)移動軟交換分布式組網(wǎng)如圖所示。對于MSC來說，將媒體網(wǎng)關(guān)分散拉遠(yuǎn)，可以更加靠近BSC，減少話務(wù)迂回，節(jié)省傳輸。對于TMSC、GMSC來說，可將媒體網(wǎng)關(guān)分散到不同的本地網(wǎng)，做到話務(wù)就近接入，集中控制。BSC本地網(wǎng)2ServerMGW1MGW2MGW4MGW3BSC本地網(wǎng)1分布式組網(wǎng)、設(shè)備獨(dú)立升級(2)移動軟交換分布式組網(wǎng)如圖所示103現(xiàn)代通信網(wǎng)絡(luò)

ModernTelecommunicationNetworkLecture3(CS)電路交換與軟交換北郵軟件學(xué)院：陳候武Chenhouwu@電話：現(xiàn)代通信網(wǎng)絡(luò)

ModernTelecommunicatio104CommunicationNetworks【通信網(wǎng)絡(luò)的分類】CommunicationNetworkSwitched

CommunicationNetworkVirtualCircuitNetwork:MPLSBroadcast

CommunicationNetwork廣播，電視，衛(wèi)星PacketSwitch(PS)-分組交換DatagramNetwork:Internet:IP因特網(wǎng)Circuit-Switched(CS)-電話CommunicationNetworks【通信網(wǎng)絡(luò)的分105通信業(yè)務(wù)網(wǎng)(ServiceNetwork)：分類：通信業(yè)務(wù)網(wǎng)(ServiceNetwork)：分類：106SwitchedNetwork：【通信交換網(wǎng)絡(luò)】SwitchedNetwork：【通信交換網(wǎng)絡(luò)】107NodeSwitching（節(jié)點交換）Anode(switch)inacircuitswitchingnetworkincominglinksoutgoinglinksNodeNodeSwitching（節(jié)點交換）Anode(108Nodes

【交換節(jié)點】Nodesmayconnecttoothernodesonly,ortostationsandothernodesNodetonodelinksusuallymultiplexed【復(fù)用】NetworkisusuallypartiallyconnectedSomeredundantconnections【冗余連接

】aredesirableforreliabilityTwodifferentswitchingtechnologiesCircuitswitching【電路交換】Packetswitching【分組交換】Nodes【交換節(jié)點】Nodesmayconnect109CS:CircuitSwitch電路交換【Overview】CS:CircuitSwitch110CS:CircuitSwitching【電路交換】Dedicatedcommunicationpathbetweentwostations【專用/獨(dú)享的通信通道】Threephases【呼叫建立：3個階段】EstablishTransferDisconnectMusthaveswitchingcapacityandchannelcapacitytoestablishconnectionMusthaveintelligencetoworkoutrouting必須具有智能以對呼叫進(jìn)行選路CS:CircuitSwitching【電路交換】De111CircuitSwitching-ApplicationsInefficientChannelcapacitydedicatedfordurationofconnectionIfnodata,capacitywastedSetup(connection)takestimeOnceconnected,transferistransparentDevelopedforvoicetraffic(phone:電話網(wǎng))CircuitSwitching-Applicatio112CS：PSTN–

網(wǎng)絡(luò)結(jié)構(gòu)PSTN–PublicSwitchedTelephoneNetworkUsesdigitaltrunksbetweenCentralOfficeswitches(CO)UsesanaloglinefromphonestoCODigitalTrunks數(shù)字中繼AnaloglineCentralOfficeCentralOfficeCS：PSTN–網(wǎng)絡(luò)結(jié)構(gòu)PSTN–PublicSw113PSTN:PublicCircuitSwitchedNetworkPSTN:PublicCircuitSwitched114CS:Components【網(wǎng)絡(luò)組成】Subscriber【用戶：電話】Devicesattachedtonetwork

Subscriberline【用戶連線】LocalLoop【本地環(huán)路】Subscriberloop【用戶環(huán)路】ConnectiontonetworkFewkmuptofewtensofkmExchange/Switch【交換機(jī)】SwitchingcentersEndoffice-supportssubscribersTrunks【中繼線】BranchesbetweenexchangesMultiplexed【復(fù)用】CS:Components【網(wǎng)絡(luò)組成】Subscribe115LegacyDigitalCircuitSwitchCentralizedIntelligenceProprietaryCodeProprietaryservicedeploymentVeryexpensiveLegacyDigitalCircuitSwitchC116CircuitSwitchElements【電路交換組成】CircuitSwitchElements【電路交換組117CircuitSwitchingConceptsDigitalSwitch【數(shù)字交換】ProvidetransparentsignalpathbetweendevicesNetworkInterface【網(wǎng)絡(luò)接口】ControlUnit【控制單元】EstablishconnectionsGenerallyondemandHandleandacknowledgerequestsDetermineifdestinationisfreeconstructpathMaintainconnectionDisconnectCircuitSwitchingConceptsDigi118NodeswitchingSystem:NodeswitchingSystem:119CS：SPC:電話數(shù)字程控交換機(jī)–模塊CS：SPC:電話數(shù)字程控交換機(jī)–模塊120CS:CirtuitSwitch

【SwitchFabric：交換矩陣】現(xiàn)代通信網(wǎng)絡(luò)課件121SwitchFabric:MxNSwitchFabric:MxN122SwitchFabric:MathgraphpresentationAinputmaysetuponeconnection(1,3,6,7),multipleconnections(4),ornoconnection(2,5,8).SwitchFabric:Mathgraphpres123SwitchFabric:數(shù)學(xué)模型Inputset:T={0,1,2,…,M-1}Outputset:R={0,1,2,…,N-1}Definition:t∈Tandr∈Rt，Rt∈R，then:c=|t,Rt|isaconnection.tisstartpointoftheconnection,r∈Rtistheendpoint.ifr∈Rt,Rt