數(shù)據(jù)通信基礎(chǔ)

1、數(shù)據(jù)通信基礎(chǔ)和競爭對手分析 1三種網(wǎng)絡(luò)的基本特征PSTN以 64K 時隙為基礎(chǔ)的線路交換限制了高帶寬的應(yīng)用過渡性的解決方案多時隙捆綁革命性的解決方案寬帶交換技術(shù)CATV單向、模擬、區(qū)域性是多種應(yīng)用的技術(shù)障礙有限的雙向改造可以解決部分的數(shù)據(jù)傳輸，對語音則無能為力數(shù)字電視的標準化才會引發(fā)真正的革命數(shù)據(jù)網(wǎng)絡(luò)以包交換為基礎(chǔ)設(shè)計之初以滿足窄帶應(yīng)用為基礎(chǔ)，可以滿足多種通信模式的要求已經(jīng)迅速發(fā)展成為可以滿足各種應(yīng)用的技術(shù)終端設(shè)備將從單一的計算機向多種終端演化2世界通信標準化組織Open versus de-factoEnsure interoperabilityStandards bodies:ISO fo

2、cuses on data communication interfacesITU-TSS focuses on telecommunications and networking standards (e.g. FR, ATM, B-ISDN)ANSI coordinates with ISO for the US standardsIEEE focuses on Local Area Networks (e.g. IEEE 802.3)EIA focuses on physical connectors (e.g. RS232)3OSI/ISO 模型OSI ModelEnd user抯 a

3、ccess to networkFormats data for presentation to userLogical sessions between end usersLogical connections for transfer of data between end users (e.g. TCP, SPX)Addressing and routing (e.g. IP, IPX, X.25 PLP)Creates and recognizes message boundaries and checks for errorsTransmits data bits over comm

4、unication circuitApplicationPresentationSessionTransportNetworkData LinkPhysical4網(wǎng)絡(luò)協(xié)議的模型和層次OSI ModelApplicationPresentationSessionTransportNetworkData LinkPhysical1234567ApplicationUtilitiesTCP UDPIPNetworkAccess(e.g. IEEE 802.3)TCP/IP SPXIPXData Link(e.g. IEEE 802.3)IPX/SPXApplicationUtilities5線路傳輸

5、的主要標準Medium SONET STMDS0ChannelsSpeed OC-1 STS-1672 51.840 OC-3 STS-3 STM-12016 155.520OC-9 STS-9 6048 466.560 OC-12 STS-12 STM-48064 622.080OC-18 STS-18 12,096 933.120OC-24 STS-24 16,1281.244 GbpsOC-36 STS-3624,1921.866 GbpsOC-48 STS-48 STM-1632,2562.488 GbpsOC-96 STS-96 64,5124.976 GbpsOC-192 STS-

6、192 STM-64 129,024 9.952Gbps6通訊的實現(xiàn)舉例ServerHubRouterHubRouterF/REthernetEthernetFrame RelayApplication(e.g. Email)Transport (TCP)Network (IP)Data Link (E)Physical UTP-3IPEcat.3IPFRRS 232IPFRRS 232IPEcat.5Application(e.g. Email)Transport (TCP)Network (IP)Data Link (E)Physical UTP-57局域網(wǎng)技術(shù)HUBStationStat

7、ionStationPrint ServerNetwork PrinterDatabase ServerAccess ServerTerminal Server8以太網(wǎng)的楨格式Developed jointly by Digital, Intel, and XeroxVery similar to IEEE 802.3Relies on special pattern of SYN characters to mark the start of frameLength indicates the length of message portion of frame (Max 1500 byte

8、s)Ethernet FrameDestinationAddress6 bytesSourceAddress6 bytesLength2 BVariablePayloadVariableCRC-324 bytes9X.25 的協(xié)議和楨結(jié)構(gòu)ApplicationPLPLAP-BX.21 bis (232C, V.35)X.25Bit StreamLayer 1Layer 2(Frame)FlagControl& AddressDataFCSFlagUser DataHeaderLayer 3(Packet)DCEDTEDCEDTEX.25X.25Virtual CircuitPDN10Frame

9、 Relay 網(wǎng)絡(luò)結(jié)構(gòu)RouterSwitchSwitchSwitchSwitchSwitchSwitchFrame Relay NetworkRouter2. Up to 50 MbpsTCP does End-to-End AcknowledgmentUser data (e.g. TCP/IP packets)up to 8187 OctetsLayer 3 Packet3. Efficient with LAN protocols10 Mbps10 MbpsFRUNIFRUNI11Frame Relay 楨結(jié)構(gòu)User dataIPInformation Field(up to 818

10、7 octet)address &ControlFlag01111110FCSFlag01111110TCPExample: TCP/IP over Frame Relay87654321Octet12DLCIDLCIFECNBECNDEEAC/READLCI: Data Link Connection IdentifierC/R: Command/Response (not used)EA: Address ExtensionDE: Discard EligibilityFECN: Forward Explicit Congestion NotificationBECN: Backward

11、Explicit Congestion Notification12TCP/IP協(xié)議組中的主要協(xié)議ETHERNET TR FDDI PPP ATM FR1IPROUTE DATAGRAMS2TCPEND TO ENDCONNECTIONSUDPSINGLE MESSAGES34WWWFTPNEWSTELNETSMTPNFSDNSSNMP13TCP/IP信息的封裝過程ApplicationTCPIPNetworkAccess(e.g. IEEE 802.3)MessagePacketPacketPacketPacketPacketTCP Header- TCP port numbers (app

12、lication)- Sequence numbers- AcknowledgmentPacketIP Header- Source and Destination Address- Time To LivePacketEthernet Header- MAC source anddestination address14Internet IP協(xié)議的結(jié)構(gòu)netidClass A0 to 127024 bits7 bitsClass B128 to 19182431hostidClass C192 to 25431hostidnetid1hostidnetid1010Example: is a

13、class B networkFirst octet is assigned by the network information center14 bits16 bits21 bits8 bitsOctet 4Octet 1Octet 2Octet 3Octet 4Octet 1Octet 2Octet 3Octet 4Octet 1Octet 2Octet 315網(wǎng)絡(luò)中的設(shè)備BridgesBest for local traffic segmentationAdvantagePlug and PlayProvide simple filteringLimitationLow Broadca

14、st controlLimited WAN capabilityLow securityRoutersBest for wide area networksAdvantageConnect dissimilar type of networksProvide Traffic filteringProvide load sharing links.High security (fireWall)LimitationComplex configurationLow LatencySwitchesBest for dedicating bandwidth to users or serversAdv

15、antagePlug and PlayLow latencyLimitationNo Broadcast controlNo WAN capabilityLow securityNo traffic filtering16網(wǎng)絡(luò)中的路由表Routing is the process of determining the route/path through the network that a message will travel from the sending computer to the receiving computerRouting occurs at several level

16、s (e.g. WAN switches, routers)SwitchSwitchSwitchSwitchSwitchSwitchSwitchABCDFGERouting Table For B17路由器在網(wǎng)絡(luò)中的位置和作用NetworkNetworkNetworkRouting TableDestination NetworkNext hopRouting TableDestination NetworkNext hopMAGELLANMAGELLANABIP is connectionlessRouting tables are generated by protocols such a

17、s RIP and OSPF18網(wǎng)絡(luò)的市場分布Carriers or service providers (56%)Global carriersNational carriersSpecial service providers (e.g. Swift, SITA,.)Enterprise networks (44%)Financial Companies (20%)Government departments (6%)Manufacturers (6%)Transportation (6%)Utilities (3%)Academic and Medical Institutions (3

18、%)19層出不窮的接入手段20各種接入手段的速度上行速率下行速率21多種接入技術(shù)存在和選擇已經(jīng)埋設(shè)的基礎(chǔ)設(shè)施在原有設(shè)施上進行改造以適應(yīng)新的應(yīng)用和競爭需求不同的應(yīng)用拉、退以及不同速率、質(zhì)量因素不同的人口密度各種技術(shù)的成本不同不同的地理環(huán)境不同的商業(yè)環(huán)境22aDSL 接入原理DSLAMATU-RATU-RATU-RPsPsPsATU-CATU-CATU-CLE C&C 08A4 接口數(shù)字廣播數(shù)據(jù)網(wǎng)絡(luò)網(wǎng)絡(luò)管理服務(wù)內(nèi)容區(qū)局 端用戶區(qū)23ADSL 頻譜的利用ADSL調(diào)制解調(diào)器的頻譜利用的劃分0 4 20 50 140 150 500 1100頻率(KHz)下行上行傳統(tǒng)電話頻譜1.5Mb/s6.3Mb/s

19、24aDSL 中的主要概念DSLAM DSL接入復(fù)用器Ps POTS 分路器ATU-C ADSL傳輸單元中心ATU-R ADSL傳輸單元遠端CAP、DTM aDSL的兩種調(diào)制方式xDSL 是利用雙絞線中的不同頻段分別傳輸語音、上行、下行信號的25 xDSL 的業(yè)務(wù)定位不適合將來的數(shù)字電視市場主要視頻業(yè)務(wù)集中在VOD和 nVOD高速Internet 接入通明高速數(shù)字傳輸xDSL 必需處于端局，不能跨PSTN局，限制了其覆蓋范圍和靈活性263Com TotalControlFront located NACHot Swapable NAC LED indicator show statusVart

20、ical card easy coolingRear located NICFlexible NIC card provide multiple interfaceSecure wiring Lock back cabinet for more security27TotalControl的邏輯結(jié)構(gòu)E1Acceess Serer30 x 56KModem30 x 56KModem30 x 56KModem30 x 56KModem30 x 56KModem30 x 56KModemE1E1E1E1E1第三代產(chǎn)品：分布中繼處理，滿足大型ISP的 多E1線路的撥號接入及新應(yīng)用的需求特點：每個E1單

21、獨處理， 提供充足的處理能力， 滿足今后新技術(shù)的要求。 E1之間不共享 TDM 總線， 克服E1間可能的干擾。 靈活的中繼資源 利用能力， 強大的后處理能力，如 Hiper Router 和 Edge Server。 支持 VOIP， FOIP 及多媒體應(yīng)用。28TotalControl板位圖HIPerARCNICTDM BusPacket BusNICDSPCardNICDSPCardNICDSPCardNICDSPCardNICDSPCardNICDSPCardNICDSPCardNICDSPCardNICDSPCardNICDSPCardNICDSPCardNICDSPCardNICDS

22、PCardNICDSPCardHIPerARCNICDistributed TrunkingRedundant Access Routers29TotalControl主要弱點分析每個E1單獨處理，沒有TDM交換功能，不能實現(xiàn)中繼合群ISDN Call 需要Modem卡，經(jīng)濟性不好滿負荷運行效率低下或者接通率低優(yōu)點：在網(wǎng)絡(luò)上應(yīng)用比較多30Ascend Max TNT43.5 cmJEDEC DRAM SlotTwo Flash PCMCIA SlotsEthernetIntershelfExpansion BusPortsConsole Port 1234567890AC or DC Powe

23、r SupplyAC or DC Power SupplyTDM BUS (64Mbps FDX)CELL BUS (155Mbps FDX)Control BUS (10 Mbps)29.5 cm31Max TNT 135670AC or DC Power SupplyAC or DC Power SupplyMain Power Supply(AC or DC)Redundant Power Supply(AC or DC)JEDEC DRAM SlotTwo Flash PCMCIA SlotsEthernetMultishelfExpansion BusPorts16Expansion SlotsConsole PortAlarm Contact14”17