現(xiàn)代通信網(wǎng)絡(luò)課件3

1、現(xiàn)代通信網(wǎng)絡(luò)現(xiàn)代通信網(wǎng)絡(luò)Modern Telecommunication NetworkLecture 3(CS)電路交換與軟交換電路交換與軟交換北郵軟件學(xué)院：陳候武北郵軟件學(xué)院：陳候武C電話：電話ommunication Networks 【通信網(wǎng)絡(luò)的分類通信網(wǎng)絡(luò)的分類】Communication NetworkSwitchedCommunication NetworkVirtual Circuit Network: MPLSBroadcastCommunication Network 廣播，電視，衛(wèi)星廣播，電視，衛(wèi)星Packet Switch(PS) - 分組交換

2、分組交換Datagram Network: Internet: IP因特網(wǎng)因特網(wǎng)Circuit-Switched(CS) - 電話電話通信業(yè)務(wù)網(wǎng)通信業(yè)務(wù)網(wǎng)(Service Network)(Service Network)：分類：分類：Switched Network：【通信交換網(wǎng)絡(luò)通信交換網(wǎng)絡(luò)】Node Switching （節(jié)點交換節(jié)點交換 ） A node (switch) in a circuit switching networkincoming linksoutgoing linksNodeNodes 【交換節(jié)點交換節(jié)點】 Nodes may connect to other no

3、des only, or to stations and other nodes Node to node links usually multiplexed 【復(fù)用】 Network is usually partially connectedpSome redundant connections 【冗余連接冗余連接 】are desirable for reliability Two different switching technologiespCircuit switching 【電路交換電路交換】pPacket switching 【分組交換分組交換】CS:Circuit Swit

4、ch電路交換電路交換 【Overview】CS: Circuit Switching 【電路交換電路交換】 Dedicated communication path between two stations 【專用/獨享的通信通道】 Three phases 【呼叫建立：呼叫建立：3個階段個階段】pEstablishpTransferpDisconnect Must have switching capacity and channel capacity to establish connection Must have intelligence to work out routingp必須必

5、須具有智能以對呼叫進行選路具有智能以對呼叫進行選路Circuit Switching - Applications InefficientpChannel capacity dedicated for duration of connectionpIf no data, capacity wasted Set up (connection) takes time Once connected, transfer is transparent Developed for voice traffic (phone: 電話網(wǎng)電話網(wǎng))CS：PSTN 網(wǎng)絡(luò)結(jié)構(gòu)網(wǎng)絡(luò)結(jié)構(gòu)lPSTN Public Switc

6、hed Telephone NetworklUses digital trunks between Central Office switches (CO)lUses analog line from phones to CODigital Trunks數(shù)字中繼數(shù)字中繼Analog lineCentralOfficeCentralOfficePSTN: Public Circuit Switched NetworkCS: Components 【網(wǎng)絡(luò)組成】 Subscriber 【用戶：電話】pDevices attached to network Subscriber line 【用戶連線用

7、戶連線】pLocal Loop 【本地環(huán)路本地環(huán)路】pSubscriber loop 【用戶環(huán)路用戶環(huán)路】pConnection to networkpFew km up to few tens of km Exchange / Switch 【交換機交換機】pSwitching centerspEnd office - supports subscribers Trunks 【中繼線中繼線】pBranches between exchangespMultiplexed 【復(fù)用復(fù)用】Legacy Digital Circuit SwitchlCentralized IntelligencelP

8、roprietary CodelProprietary service deploymentlVery expensiveTrunkCardTrunkCardTrunkCardLineCardLineCardLineCardSwitch ControllerNext SwitchNext SwitchNext SwitchSS7 NetworkCircuit Switch Elements 【電路交換組成】Circuit Switching Concepts Digital Switch 【數(shù)字交換數(shù)字交換】pProvide transparent signal path between de

9、vices Network Interface 【網(wǎng)絡(luò)接口網(wǎng)絡(luò)接口】 Control Unit 【控制單元控制單元】pEstablish connections Generally on demand Handle and acknowledge requests Determine if destination is free construct pathpMaintain connectionpDisconnectNode switching System:Node switching System:CSCS：SPC: SPC: 電話數(shù)字程控交換機電話數(shù)字程控交換機 模塊模塊CS:Cirt

10、uit Switch 【Switch Fabric：交換矩陣：交換矩陣 】Switch Fabric: M x NSwitch Fabric: Math graph presentationSwitch Fabric: Math graph presentationA input may setup one connection (1,3,6,7), multiple connections (4), or no connection (2,5,8).Switch Fabric: 數(shù)學(xué)模型數(shù)學(xué)模型 Input set: T = 0,1,2, M-1 Output set: R = 0,1,2,

11、N-1 Definition: t T and r Rt， Rt R ， then: c = | t, Rt | is a connection. t is start point of the connection, r Rt is the end point. if r Rt, Rt contains only one item,this connection is point to point. if r Rt, Rt contains more than one item,this connection is point to multi-point. Multicast: Rt R

12、; Broadcast: Rt = R connection set in switch fabric: C = | c0, c1, c2, |Switch Fabric: Switch Fabric: 連接函數(shù)連接函數(shù)連接函數(shù)連接函數(shù): input link: x (0 = x = M-1) Output link f(x) (0 = f(x) = N-1). 例如：連接函數(shù)例如：連接函數(shù): (x2, x1, x0) = x1, x0, x2 (000)=000, (001)=010, (010)=100, (111)=111Switching Fabric: Time DivisionSw

13、itching Fabric: Time Division Time-slot switching is a device, which buffers m incoming time-slots, arranges new transmit order and transmits n time-slots Used in Packet switch and ATM as well as digital telephone switchSwitching Fabric: Space DivisionSwitching Fabric: Space DivisionTime/Space Divis

14、ion Multiplexing TIME SWITCHTIME SWITCHTIME SWITCHTIME SWITCHTIME SWITCHTIME SWITCHSPACE SWITCHCS：Blocking or Non-blocking Blocking 【阻塞】pA network is unable to connect stations because all paths are in usepA blocking network allows this 【網(wǎng)絡(luò)允許Blocking】pUsed on voice systems Short duration calls Non-b

15、locking 【無阻塞】pPermits all stations to connect (in pairs) at oncepUsed for some data connectionsSwitching Fabric: BlockingSwitching Fabric: Blocking解決解決方案：方案：Multistage SwitchlReduced number of cross pointslMore than one path through networkp Increased reliabilitylMore complex controllMay be blocking

16、解決解決方案：兩級交換矩陣方案：兩級交換矩陣解決方案解決方案：Three Stage Switchx xx xx xx xCS：TST交換矩陣交換矩陣 - - 實例：實例：TST - Time switch and Space switch(1) T 接線器: A user info. Occupy a time slot 8 bits code.（3 3）TST TST 接線器接線器 512 x 512 Time Slots512 x 512 Time SlotsCS:電路交換電路交換 【PSTN: Trunk Multiplexing】CO1 CO2: Truck Multiplexing

17、Mux.11111222.64kb/s voice channelt4 t3 t2 t12Mb/s output signal同步時分復(fù)用：同步時分復(fù)用：Synchronous TDMSynchronous TDME1: 2Mb/s frame structureAll Timeslots contain 8 bit words(PCM, Data, Subrate, n x 64 kb/s)Network Signaling - CAS or CCS01231415 1617303101 frame - 256 bits - 125msFrame Alignment Word3.9usNet

18、work SignalingChannels 1 to 15Channels 16 to 30 MUX MUX MUX MUX MUX12 3 4 1234 E1 E1 E1 E1E2E2E2E2 E52.048 8.448 34.368 139.264 561.480Mbps Mbps Mbps Mbps Mbps CH2 CH1 CH32E3 1E3 2E3 3E3 4 E4 1 E4 2 E4 3 E4 4 ITU-T E1 DIGITAL MULTIPLEXING HIERARCHYE1 E2 E3 E4 E5ANSI：T1 - T-carrier system 1.544MlEach

19、 frame carries one sample (8 bits) for each 24 channels, plus one framing bit = 193 bitsl193 * 8000 (samples/sec) = 1.544 Mbit/sec = T-1Channel 1Channel 2Channel 3Channel 24Channel1Channel2Channel3Channel24Framing Bit1 D4 FrameTDM ANSI: T1/DS1 Frame Structure - 1.544 Mbps Every 8th bit used for sign

20、alingpinefficient01221 22620231 frame - 193 bits - 24 channelsBit 8 - reserved for signalingFraming bit34501Bits 1-7 PayloadANSI: DIGITAL MULTIPLEXING HIERARCHYT1 T2 T3 T4 T5 MUX MUX MUX MUX MUX12 T3 13 T3 24 T3 35 T3 46 T3 57 T3 6123412 T1 T1 T1 T1T2T2T2T2T2T2T2 T4 T4T5 CH1 CH2 CH2424VF1.544 6.312

21、44.736 274.176 560.160 Mbps Mbps Mbps Mbps Mbps Statistical TDM 【統(tǒng)計時分復(fù)用統(tǒng)計時分復(fù)用】 In Synchronous TDM many slots are wasted Statistical TDM allocates time slots dynamically based on demand Multiplexer scans input lines and collects data until frame full Data rate on line lower than aggregate rates of in

22、put linesStatistical TDM Frame FormatsStatistical TDM v Synchronous TDMSynchronous TDM Statistics TDM divides a data link into some logic sub-channelStatistical TDM v Synchronous TDM：FormatsStatistical TDM 舉例：舉例：HDLCHDLC HDLC： High Level Data Link Control Synchronous transmission All transmissions i

23、n frames Single frame format for all data and control exchangesHDLC：Frame Structure FlagAddress ControlInformationFCSFlag8bits8extendable8/16variable816 / 32trailerFrame CheckSumHDLC：Address Field Identifies secondary station that sent or will receive frame Usually 8 bits long May be extended to mul

24、tiples of 7 bitspLSB of each octet indicates that it is the last octet (1) or not (0) All ones (11111111) is broadcastCS:電路交換電路交換 【PSTN: Signaling 信令信令】與與【Call Control：呼叫控制：呼叫控制】CS: PSTN 控制信令與呼叫控制控制信令與呼叫控制 各階段各階段lEach conversation requires a channel switched throughout the networkl呼叫請求：呼叫請求：Call req

25、uest；呼叫建立：；呼叫建立：Call established; 呼叫接收呼叫接收1. Call is requested3. Channel is established2. Call is acceptedPSTNCS: PSTN 電話號碼編碼方案電話號碼編碼方案l3 digits area code 【區(qū)域碼區(qū)域碼】+ 3 digits office code 【局碼局碼】 + 4 digits phone 【本局隨機碼本局隨機碼】lEach Local Exchange Carrier switch (LEC：本地交換局：本地交換局) are assigned a block of

26、at least 10,000 numberslThe Inter-Exchange Carrier (IXC：匯接局：匯接局) switches are responsible for transmitting long distanceIXC212LEC5554210(212) 555 4210CS: PSTN Call Routing - 1lInternational Numbering Plan E.164 【國際電話號碼方案國際電話號碼方案】luse prefix-based dialing4085644555212PSTN1+212+555+5644SS7CS: PSTN Cal

27、l Routing - 2lThe first LEC 【本地交換機本地交換機】receives a call, seeing 1 as the first digit and then passes the call on to the IXC switch. lThe IXC then routes the call, via SS7, to the remote IXC responsible for 212. 【遠端的212中繼局】lThe 212 IXC looks at the office code and passes it on to the 555 LEC switch.

28、【515本地局】lThe 555 LEC switch then checks the station code and signals the appropriate phoneSignaling: Control Functions 【控制功能】lAudible communication with subscriberlTransmission of dialed numberlCall can not be completed indicationlCall ended indicationlSignal to ring phonelBilling infolEquipment and

29、 trunk status infolDiagnostic infolControl of specialist equipmentPSTN：用戶信令用戶信令lUses loop-start signaling 【環(huán)路信令】pIndicates if the phone is on-hook or off-hook, or generates ring-tone on phone. pCloses circuit when phone is off-hooklUses two wires, tip and ringTipFXSRingSwitch to Switch Signaling：【中繼

30、信令中繼信令】 Subscribers connected to different switches Originating switch seizes interswitch trunk Send off hook signal on trunk, requesting digit register at target switch (for address) Terminating switch sends off hook followed by on hook (wink) to show register ready Originating switch sends address

31、中繼信令：基本呼叫流程：中繼信令：基本呼叫流程：中繼信令：中繼信令：呼叫控制呼叫控制：FSM Finite State Machine (有限狀態(tài)機有限狀態(tài)機 主叫方主叫方 )掛機狀態(tài)掛機狀態(tài)摘機狀態(tài)摘機狀態(tài)通話狀態(tài)通話狀態(tài)撥號狀態(tài)撥號狀態(tài)忙音狀態(tài)忙音狀態(tài)振鈴狀態(tài)振鈴狀態(tài)請求呼叫狀態(tài)請求呼叫狀態(tài)回鈴狀態(tài)回鈴狀態(tài)摘機摘機撥號撥號撥號正確撥號正確撥號撥號撥號錯誤撥號錯誤被叫振鈴被叫振鈴被叫摘機被叫摘機被叫用戶忙被叫用戶忙被叫無應(yīng)答被叫無應(yīng)答被叫掛機被叫掛機主叫掛機主叫掛機收到新的呼叫收到新的呼叫摘機摘機 PSTN: Signaling Methods【中繼信令分類中繼信令分類】lCAS Chann

32、el Associated Signaling 【隨路信令】pSignaling associated with each channel has fixed placement within framepTraditional T-1 and E-1 for voice uses CASlCCS Common Channel Signaling 【共路信令】pSignaling passed via messaging protocol, out-of-band signalingpCan carry a wide variety of messages, e.g. Caller-ID et

33、cpISDN uses a CCS-based protocol Q.931pQ.SIG which is typically used for PBX-to-PBX connectivity, and is a variant of Q.931, is CCD-basedpSS7 is the CCS-based protocol used in the PSTN, i.e. between COsDrawbacks 【缺點缺點】of In CASlLimited transfer ratelDelay between entering address (dialing) and conne

34、ctionlOvercome by use of common channel signalingCAS v. CCSSS7：Signaling System Number 7 SS7：Common channel signaling scheme ISDN Optimized for 64k digital channel network Call control, remote control, management and maintenance Reliable means of transfer of info in sequence Will operate over analog

35、 and below 64k Point to point terrestrial and satellite linksPSTN SS7 /Signaling System 7SS7 messages are exchanged between network elements on bi-directional channels (typically T1 lines) called signaling links. Trunk LinesSSP(CO)SSP(CO)STPSS7STPT-1T-1PSTN SS7 Signaling Points l SS7 network is crit

36、ical to call processing, SCPs and STPs are usually deployed in mated pair configurations in separate physical locations to ensure network-wide service in the event of an isolated failure. lLinks between signaling points are also provisioned in pairs. Traffic is shared across all links in the linkset

37、. If one of the links fails, the signaling traffic is rerouted over another link in the linkset. SS7 LinksSTPSTPSSPSSPSCPSCPSS7 LinksTrunk LinksSS7：網(wǎng)元功能：網(wǎng)元功能lSSP (Service Switching Point) pSSPs are switches that originate, terminate, or tandem calls. pAn SSP sends signaling messages to other SSPs to

38、 setup, manage, and release voice circuits required to complete a call.p An SSP may also send a query message to a SCP to determine how to route a call. 【智能網(wǎng)功能智能網(wǎng)功能】pThe functionality of the SSP is usually integrated into the CO (Central Office switch：終端局：終端局).lSTP (Signal Transfer Point) 【信號轉(zhuǎn)接點信號轉(zhuǎn)接

39、點】pNetwork traffic between signaling points may be routed via a packet switch called an STP. pAn STP routes each incoming message to an outgoing signaling link based on routing information contained in the SS7 message. An STP can also act as a firewall to screen SS7 messages exchanged with other net

40、works.lSCP (Service Control Point) 【信號控制點信號控制點】pAn SCP is a centralized database that tells an SSP how to route a call (e.g., a toll-free 1-800/888 call ). pIt sends a response to the originating SSP containing the routing number(s) associated with the dialed number.SS7：信令功能 SS7 在移動網(wǎng)絡(luò)中漫游功能的應(yīng)用CS:電路交換

41、電路交換 【PSTN: 電話網(wǎng)組網(wǎng)原理電話網(wǎng)組網(wǎng)原理】CS：AT&T Telephony Hierarchy110987324561231231236566672282292301298129913001234519,000200 million telephones19,000 endoffices1300 tolloffices230 primaryoffices67 sectionaloffices10 regionaloffices(full mesh)Class 5Class 4Class 3Class 2Class 1CS：Telephone Network ModelRegion

42、al CenterClass 1 switchSectional CenterClass 2 switchPrimary CenterClass 3 switchToll CenterClass 4 switchEnd OfficeClass 5 switchRegional CenterClass 1 switchSectional CenterClass 2 switchPrimary CenterClass 3 switchToll CenterClass 4 switchEnd OfficeClass 5 switchVoiceVoiceTo otherRegional centers

43、Sectional centersPrimary centersToll centersEnd officesTo otherPrimary centersToll centersEnd officesTo otherClass 4 toll pointsEnd officesFigure 1.1 Telephone Network ModelLegend:LoopDirect TrunkToll-Connecting TrunkToll TrunkCSCS：傳統(tǒng)電話網(wǎng)分層結(jié)構(gòu)的問題：傳統(tǒng)電話網(wǎng)分層結(jié)構(gòu)的問題：l層次太多層次太多p匯接層次（轉(zhuǎn)接交換機）過多導(dǎo)致呼叫建立延遲p傳輸損失。降低了呼叫

44、接通率l降低了系統(tǒng)的可靠性降低了系統(tǒng)的可靠性p一個轉(zhuǎn)接交換機出問題，將阻塞整個網(wǎng)絡(luò)l網(wǎng)絡(luò)管理復(fù)雜網(wǎng)絡(luò)管理復(fù)雜我國電話網(wǎng)我國電話網(wǎng)：Two levels of transit network l長途網(wǎng)絡(luò)結(jié)構(gòu)正在從 4 層演進到 2 層（扁平化）pDC1 (direct connection 1) 高層（省間層）pDC2 (direct connection 2) 低層（省內(nèi)層）CS：局間中繼聯(lián)系方式局間中繼聯(lián)系方式DC1 省際：互聯(lián)至其他??；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：本地網(wǎng)互聯(lián)方式本地網(wǎng)互聯(lián)方式All local switches ar

45、e connected each other by direct trucks. Suitable to less local switches in the same area.CS: 電話網(wǎng)的路由選擇電話網(wǎng)的路由選擇高效直達路由高效直達路由(H): 永遠是首選永遠是首選低呼損直達路由低呼損直達路由(L): 最后選擇最后選擇用戶用戶A 呼叫呼叫 用戶用戶B：A1-B1, A1-B2-B1, A1-A2-B2-B1, A1-A2-B3-B2-B1, A1-A2-A3-B3-B2-B1lMany connections will need paths through more than one

46、switchlNeed to find a routepEfficiencypResilience 【彈性彈性】lPublic telephone switches are a tree structurepStatic routing uses the same approach all the time 【靜態(tài)路由靜態(tài)路由】lDynamic routing allows for changes in routing depending on traffic 【動態(tài)路由動態(tài)路由】pUses a peer structure for nodeslPossible routes between

47、end offices predefinedlOriginating switch selects appropriate routelRoutes listed in preference orderlDifferent sets of routes may be used at different timesCS:電路交換電路交換 【SoftSwitch:軟交換軟交換】CS 存在問題：存在問題：解決方案解決方案Softswitch Soft-switch： 優(yōu)點General purpose: computer running software to make it a smart pho

48、ne switchLower costsGreater functionalitypPacketizing of digitized voice datapAllowing voice over IPMost complex part of telephone network switch is 【software controlling call process】pCall routingpCall processing logicpTypically running on proprietary processorSeparate call processing from hardware

49、 function of switchPhysical switching done by media gatewayCall processing done by media gateway controller 【softswitch】Traditional Circuit SwitchingCS：Softswitch 【軟交換結(jié)構(gòu)】Media Gateway Controller【媒體網(wǎng)關(guān)控制器媒體網(wǎng)關(guān)控制器】 = Softswitch ：軟交換：軟交換CS：軟交換系統(tǒng)與傳統(tǒng)設(shè)備區(qū)別：軟交換系統(tǒng)與傳統(tǒng)設(shè)備區(qū)別 電路交換模型電路交換模型呼叫控制呼叫控制SS7SS7 Line Line Ca

50、rdCardTrunk Trunk CardCardTime Time Slot Slot 交交換換T TD DM MT TD DM M管理系統(tǒng)管理系統(tǒng)計費系統(tǒng)計費系統(tǒng)IPIPATMATM軟交換軟交換SS7SS7MGMGMGMGIPIPATMATMH.248/MGCPH.248/MGCPH.248/MGCPH.248/MGCP軟交換模型軟交換模型T TD DM MT TD DM M分組網(wǎng)分組網(wǎng)擴展業(yè)務(wù)擴展業(yè)務(wù)管理系統(tǒng)管理系統(tǒng)計費系統(tǒng)計費系統(tǒng)將傳統(tǒng)交換機的功能模塊分離成為獨立的網(wǎng)絡(luò)部件，各個部件可以按相應(yīng)的功將傳統(tǒng)交換機的功能模塊分離成為獨立的網(wǎng)絡(luò)部件，各個部件可以按相應(yīng)的功能劃分各自獨立發(fā)展。

51、部件間的協(xié)議接口基于相應(yīng)的標準能劃分各自獨立發(fā)展。部件間的協(xié)議接口基于相應(yīng)的標準,有利于實現(xiàn)各種異構(gòu)有利于實現(xiàn)各種異構(gòu)網(wǎng)的互通。網(wǎng)的互通。CSCS：傳統(tǒng)：傳統(tǒng)PSTNPSTN網(wǎng)絡(luò)存在問題網(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: Softswitch: PSTN - IP ArchSS7SignallingGatewayPSTNTrunksMediaGateway(Trunking)PSTNOriginating o

52、rTandemSwitch(es)SS7NetworkMediaGatewayControllerMediaGateway(Trunking)RTP/UDP/IP StreamMegacoSS7SignallingGatewayMegacoMediaGatewayControllerPSTNTrunksVoIP TerminalsPSTNOriginating orTandemSwitch(es)SS7NetworkM3UA/SCTPSS7SS7TDMTDMM3UA/SCTPSIP-TCSCS：軟交換結(jié)構(gòu)：軟交換結(jié)構(gòu) 網(wǎng)元組成網(wǎng)元組成 Media Gateway Controller（MGC）

53、：Softswitch: Signaling Gateway 【信令網(wǎng)關(guān)】 Media Gateway 【媒體網(wǎng)關(guān)】p Trunking gatewayp Line Gatewayp Residential Gateway 軟交換的新業(yè)務(wù)成本僅為軟交換的新業(yè)務(wù)成本僅為PSTN的的【五分之一五分之一】。開發(fā)周。開發(fā)周期為期為PSTN的的【十分之一十分之一】。占地是傳統(tǒng)電路交換機的十。占地是傳統(tǒng)電路交換機的十分之一。分之一。CS：MGC 媒體網(wǎng)關(guān)控制器的功能媒體網(wǎng)關(guān)控制器的功能 Contains all call control intelligence Implements call level

54、 features (forward, transfer, conference, hold, )掛機狀態(tài)掛機狀態(tài)摘機狀態(tài)摘機狀態(tài)通話狀態(tài)通話狀態(tài)撥號狀態(tài)撥號狀態(tài)忙音狀態(tài)忙音狀態(tài)振鈴狀態(tài)振鈴狀態(tài)請求呼叫狀態(tài)請求呼叫狀態(tài)回鈴狀態(tài)回鈴狀態(tài)摘機摘機撥號撥號撥號正確撥號正確撥號撥號撥號錯誤撥號錯誤被叫振鈴被叫振鈴被叫摘機被叫摘機被叫用戶忙被叫用戶忙被叫無應(yīng)答被叫無應(yīng)答被叫掛機被叫掛機主叫掛機主叫掛機收到新的呼叫收到新的呼叫摘機摘機 Master / slave control of MGs by MGCsp Connection controlp Device control and configur

55、ation 軟交換機軟交換機【MGC】控制各種網(wǎng)關(guān)協(xié)議：控制各種網(wǎng)關(guān)協(xié)議：p Megaco 協(xié)議協(xié)議 （當(dāng)前使用）（當(dāng)前使用）p MGCP 協(xié)議協(xié)議 （過去使用）（過去使用）CS：MGC 媒體網(wǎng)關(guān)控制器協(xié)議媒體網(wǎng)關(guān)控制器協(xié)議Endpoint(eg. H.323 Gateway, Terminal, MCU) Gateway Function(eg. H.323 Gateway, Terminal, MCU) Call AgentMedia Gateway ControllerSignalling GatewayPSTN,ATM,etctrunkslinesSS7 etcSigtranAnalo

56、gMedia GatewayPSTN trunkingMedia GatewayPSTN lineMedia GatewayIP PhoneMedia GatewayMegaco ScopeCS: 軟交換系統(tǒng)組成與功能軟交換系統(tǒng)組成與功能 Megaco ProtocolCall control (eg. H.323, SIP)H.248IP (or ATM) NetworkPBX/COPBX/COMedia GW ControllerMedia GatewayDevicecontrolDevicecontrolIP PhoneMedia GatewayTelephone/Residential

57、Media GatewayPSTN trunkingMedia GatewayPSTN lineMedia GatewayPBXMedia GatewayConnection and device controlNo call processing, no call modelService-independentCS: Signaling Gateway【信令網(wǎng)關(guān)信令網(wǎng)關(guān)】：功能：功能lSignaling Gateways provide interaction between the SS7 network and Media Gateway Controllers.lConvert SS

58、7 to IP packetslConvert IP to SS7 packetslSignaling transport (SS7, SIP-T, Q.931)lExtremely securelExtremely fault tolerantMedia GW ControllerTrunk GatewayMegaco/H.248Virtual SwitchSigtransSIP, H.323Media GatewaySignalling GatewayPBXD-channelB-channelsPRIVirtual SwitchRTPSigtransSignaling GatewaySig

59、naling GatewaySS7COSigtransSigtransCS: Signaling Gateway【信令網(wǎng)關(guān)信令網(wǎng)關(guān)】- 2- 2Softswitch: MGC 之間中繼信令之間中繼信令 SIP Session Initial Protocol 在Softswitch 網(wǎng)絡(luò)，我們需要一個中繼信令取代SS7 SIP 信令是最佳選擇SS7 Architecture 【專用網(wǎng)絡(luò)：無法共享專用網(wǎng)絡(luò)：無法共享】SS7：ISUP Call Establishment/ReleaseSIPAudio CodecG.711G.723G.729Video CodecH.261H.263RTPRTCPLAN InterfaceTCPIPUDPSIP Architecture l A signaling protocolpThe setup, modification, and tear-down of multime