cisco教材.ppt

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1、cisco教材教材2Cisco Systems ConfidentialVisualizing a DOCSIS over HFC NetworkSPLITS SIGNAL INTOTWO EQUAL SIGNALSLOSS = 10 LOG 1 / 2 = - 3 dB + Insertion loss = - 3.5 dBAvailable with MULTIPLEEQUAL or NON EQUAL PORTS.Available for Electrical or OpticalApplications0 dBmV- 3.5 dBmV - 3.5 dBmVSUBSCRIBER TAP

2、TWO BASIC TYPESPOWER PASSINGPOWER BLOCKINGABCA - B Insertion Loss decreases as drop loss increasesA - C Insertion Loss higher, and varies with number of drops Number of drops typically 2, 4, 8 C - B Isolation increases as drop loss increases0 dBmV -0.5 dBmV- 36 dBmV36 dB drop loss15Cisco Systems Con

3、fidentialEQUALIZATION and ATTENUATION55 - 750 MHZINPUTEQUALIZERSHAPE55 - 750 MHZOUTPUTSlopeAdjustcableequalizerFrequencyLoss(dB)COAXIAL CABLE TRANSMISSION SYSTEMSBASIC ONE WAY AMPLIFIERACCouplerACCouplerATTATTINTERSTAGE TILTING16Cisco Systems ConfidentialCOAXIAL CABLE TRANSMISSION SYSTEMSBASIC ONE W

4、AY AMPLIFIERBASIC TWO WAY AMPLIFIERACCouplerACCouplerATTATTHigh PassLowPassHigh PassLowPassATTATTATT17Cisco Systems ConfidentialCOAXIAL CABLE TRANSMISSION SYSTEMSATTATTHigh PassLowPassHigh PassLowPassATTCPLRCPLRHigh PassLowPassBASIC TWO WAY AMPLIFIER with BRIDGER18Cisco Systems ConfidentialUp Conver

5、ter / Optical NodeFrequencySynthesizerATTIFRFUp-converterOptical NodeOpticalElectricalDiplexer19Cisco Systems ConfidentialCOAXIAL CABLE TRANSMISSION SYSTEMSCOMMON EQUIPMENT AND APPLICATIONSAMPLIFIER (FORWARD)AMPLIFIER ( TWO WAY)INPUT+ 12 dBmVINPUT+ 12dBmVOUTPUT + 34 dBmVOUTPUT + 34 dBmVCABLE LOSS -

6、22dB GAIN+ 22 dBGAIN+ 22 dBCABLE LOSS - 22dBDOWN STREAM DOWN STREAM UP STREAMONE WAY TRANSMISSIONTWO WAY TRANSMISSION20Cisco Systems ConfidentialCOAXIAL CABLE TRANSMISSION SYSTEMSAFFECTS OF TEMPERATURE and COUNTERMEASURELOSS (dB)TEMPERATURE (deg F)relative to reference frequencyAGC (Autmatic Gain Co

7、ntrol ) is the countermeasureOutput signal is sampled, and fed back to the input of the amplifier to compensate for temperature, and to maintain a constantoutput. AGC functionality is distributed when needed to achieve stability at minimal cost.DISTRIBUTION OF AGC FUNCTIONAMP 1 (AGC) AMP 2 (MAN) AMP

8、 3 (MAN) AMP 4 (AGC)TEMP OUT CABLE IN OUT CABLE IN OUT CABLE IN OUTdeg F PUT LOSS PUT PUT LOSS PUT PUT LOSS PUT PUT+90+40 32.7 +7.3 +39.3 32.7 +6.6 +38.6 32.7 +5.9 +40+68+40 32.0 +8.0 +40.0 32.0 +8.0 +40.0 32.0 +8.0 +40+0+40 29.8 +10.2 +42.2 29.8 +12.4 +44.4 29. +14.6 +4021Cisco Systems Confidential

9、COAXIAL CABLE TRANSMISSION SYSTEMSESTABLISHING SIGNAL LEVELS+18 +40100 Ft TAP 600Ft TAP 500 Ft TAPdBmV dBmV 1 dB (2/29) 6 dB (2/20) 5 dB (2/17)DROP LEVEL +10 dBmV +12.6 dBmV +10 dBmVDROP LOSS100 Ft 1 dB 100 Ft 1 dB 100 Ft 1 dBDEVICE / CABLEINSERT LOSS/GAINOUTPUT LEVEL DROP LEVELAMPLIFIER+ 40 dBmV100

10、 Ft .500 CABLE1 dB+ 39 dBmV2 / 29 TAP.4 dB+38.6 dBmV+10 dBmV600 Ft .500 Cable6 dB+32.6 dBmV2 / 20 TAP.6 dB+32 dBmV+12.6 dBmV500 Ft .500 CABLE5 dB+27 dBmV2 / 17 TAP.7 dB+26.3 dBmV+10 dBmV(+9 dBmV)(+11.6 dBmV)(+9 dBmV)22Cisco Systems ConfidentialHFC (Hybrid Fiber Coaxial) TechnologyCoaxial Cable Netwo

11、rk 2000 HOMESCOAXHeadendCoaxial Cable Bypass and eliminate coaxial cable and amplifiers from a portion of the downstream path and replace the link with fiber Make ready for two way operation!23Cisco Systems ConfidentialNODENTypically Fewer than Amplifiers in CascadeHFC Cable Network The signal is tr

12、ansmitted over fiber to the node, where it is converted to an electrical signal and forwarded to the subscriber over existing coaxial cable Provision is made to support return traffic for future services 2000 HOMESHeadendCOAXFiberHFC (Hybrid Fiber Coaxial) Technology24Cisco Systems ConfidentialCABLE

13、 SYSTEM TOPOLOGY (optical node)TO / FROMHEAD ENDTYPICALLY FEWER THAN FIVE AMPLIFIERS IN CASCADETYPICALLY 125 TO 2000 HOMES SUPPORTED BY ONE NODE25Cisco Systems Confidential 80 ChannelsCNNHBOESPNHFC to the nodeAlternate feed to the nodeTarget nodes of 500 homesFewer amplifiersCable NetworkCOAXDropSet

14、top TVAlternate FeedReliability, Increased BandwidthHubHFC (Hybrid Fiber Coaxial) Technology26Presentation_ID 1999, Cisco Systems, Inc. DOCSIS HardwareSpecifications27Cisco Systems ConfidentialDOCSIS Hardware Specifications (General)Frequency RangeUpstream:5 to 42 MHzDownstream:88 to 860 MHz (User d

15、ependent)BandwidthUpstream:200, 400, 800, 1600, 3200 KHzDownstream:6 MHzModulation ModesUpstream:QPSK, or 16 QAMDownstream:64 or 256 QAMSymbol RatesUpstream:160, 320, 640, 1280, 2560 Ksym/secDownstream:5.056941 or 5.360537 Msym/sec28Cisco Systems Confidential DOCSIS Hardware Specifications (General)

16、CMTS Power Level RangeUpstream:200 KHz-16 to + 14 dBmV400 KHz-13 to + 17 dBmV800 KHz-10 to + 20 dBmV1600 KHz-7 to + 23 dBmV3200 KHz-4 to + 26 dBmVDownstream:+50 to + 61 dBmVCable Modem Power Level Range (1 dB steps)Output:QPSK +8 to +58 dBmV 16 QAM +8 to +55 dBmVInput:64 QAM-15 to + 15 dBmVTransmiss

17、ion Level- 6 to - 10 dBc29Cisco Systems ConfidentialMULTIPLEXING CONCEPTS Multiplexing:TDM (Time Division Multiplexing)TDMA (Time Division Multiple AccessFDM (Frequency Division Multiplexing)30Cisco Systems ConfidentialMULTIPLEXING CONCEPTS Multiplexing:TDM (Time Division Multiplexing)Time slots wit

18、hin a channel shared adaptively by multiple users depending upon service demand. (Used for DOCSIS Downstream) TDMA (Time Division Multiple Access)tn (Used for DOCSIS Upstream)t2FDM (Frequency Division Multiplexing)Signals positioned in Frequency domainOneSourceMultiple Sourcest0t131Cisco Systems Con

19、fidentialSharing time on the same mediaFrame Relay is TDMSharing freq spectrum on the same mediaVideo over Cable is FDMTimeFrequencySlow Bit Stream 1FDM SignalTimeTimeTDM SignalFrequencySignal 1FrequencySlow Bit Stream 2Signal 2Fast Bit StreamModulated SignalMULTIPLEXING CONCEPTS 32Cisco Systems Con

20、fidentialDigital ModulationUpstream:Downstream:QPSK; 16 QAM64 QAM; 256 QAMQPSKIIQQ33Cisco Systems ConfidentialMeasurement of Transmission QualityErred bits among total transmitted payloadBER of 1 in 10 million pay load bits acceptableMain cause is low C/NSharp thresholdBERQPSKQAM-256QAM-64Bit Error

21、RateC/N dB10102030400QAM-161010100-5-10-2010-734Cisco Systems ConfidentialRF Measurements ToolsSpectrum analyzersScalelog base 10 PowerAbsolute (dBmV)Relative (dB) NoiseS/NSignal to noise ratio of base band signalC/NCarrier to noise ratio of modulated signalSpectrum Analyzer35Cisco Systems Confident

22、ialDownstream Carriers36Cisco Systems ConfidentialUpstream Carriers37Cisco Systems ConfidentialVideo Signal:AmplitudedBmVVideo CarrierColor & LuminanceAudio Carrier3.58 MHz4.5 MHz6.0 MHzOne Video SignalFrequency MHz0-10-20-30-40-50Noisevisual, audiocolor & luminance Unmodulated signalTypes if Video

23、SignalsNTSC, PAL, SECAMITU (CCIR) Broadcast Standards38Cisco Systems ConfidentialComposite Downstream Spectrum:AmplitudedBmVVideo6.0 MHzMultiple NTSC ChannelsFrequency MHz0-10-20-30-40-50Down StreamQAM DataVideo6.0 MHz6.0 MHz39Cisco Systems ConfidentialMeasurment of Transmission Quality BERQPSKQAM-2

24、56QAM-64C/N dB10102030400QAM-161010100-5-10-2010-7BER with FEC25 dB 35 dBDOCSIS SpecificationFEC permits operationin a noisy environment40Presentation_ID 1999, Cisco Systems, Inc. DOCSISServer Types and Purpose41Cisco Systems ConfidentialDOCSIS Server RequirementsMandatory Servers DHCP (Dynamic Host

25、 Control Protocol) Server RFC 2131: Dynamically provides and re-uses IP addresses to CM and PC ToD (Time Of Day) ServerRFC 868:Provides Timestamp for Logged events. TFTP (Trivial File Transfer Protocol) ServerRFC 1350:Provides Modem Configuration files.Optional ServersDNS (Domain Name Server)Securit

26、y ServerLog Server42Cisco Systems ConfidentialCisco Network Registrar in HeadendTFTP ServerCable ModemTerminationSystem RackDHCP/DNSNetwork RegistrarSecurity ServerRemoteAccessServerRackRouters,etc.Internet Time Server Log Server43Presentation_ID 1999, Cisco Systems, Inc. Module 4 DOCSIS Protocoland

27、 Signaling Sequence44Cisco Systems ConfidentialApplicationsTCP or UDPIPIEEE 802.2DOCSIS MAC (MPEG Frames-Downstream)TDMADigital IF Modulation(QPSK or QAM-16)TDMDigital RF Modulation(QAM-64 or QAM-256)DOCSISControlMessagesDOCSIS Protocol and Signal Sequence45Cisco Systems ConfidentialFrames & Timing1

28、88 Byte, 4 Byte header Clock Synch messages from HE (613 per sec)One source per DSMultiple sources per US, requiring time sharingCable modems identified by 13 bit Service ID (SID)Downstream supports 8175 SIDs with additional 16 reserved. Time allocation MAP from HE (periodic) US time allocated for C

29、able modems in mini slots (Mini Slot = 8 ticks, Tick = 6.25 sec) Shared time slots for Maintenance & Requests (e.g. for new modems with no SID to come online). Upstream uses contention based sub channelsDOCSIS Protocol and Signal Sequence46Cisco Systems ConfidentialLink Establishment Broadcast(One p

30、er 1.63 msec) for QAMWait for Clock SynchSet signaling clockWait for UCDSet US Channel Freq Broadcast US Channel Descriptor,DS Channel ID & Minislot size(One per sec per US Channel)Broadcast Contains US Time Sharing Info(One per 4 ms per US Channel)Wait for MAPLook for Shared Request Slots(Availabil

31、ity is Variable)DOCSIS Protocol and Signal SequenceDownstream and Upstream Frequency Established47Cisco Systems Confidential(One per 30 sec per modem)(Can be sent as needed)US/DS Frequency can be changedContains (Sent as needed)US/DS Frequency can be changedWait for Ranging ResponseAdjust Clock (in

32、6.25 us Ticks)+3dBmV increments until CMTS receivesOnly in shared Request slotsUse (Service ID)Wait for 1st Keep AliveNow in allocated Maintenance slotAdjust Power (in 0.25 dB steps)(Cable modem HFC Interface Line Protocol Up, not On-Line yet)Maintain Station Link using periodic Keep AlivesDOCSIS Pr

33、otocol and Signal SequenceInsertR1R248Cisco Systems ConfidentialCable Modem SetupAccepts Initial lP AddressOnly in shared Request slotsUse (Service ID)(Needed for every use of US)Contains , Default GW,ToD Server, TFTP Server Addr andTFTP Boot Config File Name.BroadcastContains US time sharing inform

34、ation(One per 4 ms per US Channel)Grant Returned when successfulIn Allocated slotsTOD CompleteContains Time of Day per (Not NTP)DOCSIS Protocol and Signal SequenceNow in Allocated SlotsDHCP offers an IP addressIP Address Assigned(CMAC_LOG_DHCP_Complete)49Cisco Systems ConfidentialCable Modem Setup (

35、Cont.)Contains ParametersSpecifies Privacy, new softwaredownload, etc.Send TFTP Boot File nameNow in allocated slotsMaintain Station Link using periodic Keep AlivesSend QoS Parameters in Allocated SlotsContains Modem registeredDOCSIS Protocol and Signal Sequence50Cisco Systems ConfidentialBaseline P

36、rivacyGenerate Private KEKEncrypt KEK by Public KeyDecrypt KEK using Public Key is 7 days (Configurable 1 to 70 days)Request TEKSend Request KEKOnly Data inside IEEE 802.2 frame is encrypted using TEK40/56 bit DES encryption supportedMust re-establish keys within configured Grace Period before Life

37、expiryGenerate Private TEKEncrypt TEK by KEKDecrypt TEK using KEK is 12 hours(Configurable 30 min to 7 days)DOCSIS Protocol and Signal Sequence51Cisco Systems ConfidentialModem Initialization SequencePower ONScan for Downstream ChannelDwonstream SyncEstablishedEstablish SecurityObtain UpstreamParame

38、tersUpstream ParametersAcquiredStart RangingComplete Ranging andAuto AdjustmentsEstablish IP ConnectivityIP CompleteEstablish TODTOD EstablishedInitialize Baseline PrivacySecurity EstablishedTransfer OperationalParametersTransfer CompleteRegister withuBR7246Registration CompleteBaseline Privacy Init

39、ializedOperational52Presentation_ID 1999, Cisco Systems, Inc. DOCSIS Protocoland Signaling SequenceDemonstration53Cisco Systems Confidentialoffline - modem considered offlineinit(r1) - modem sent initial ranginginit(r2) - modem is ranginginit(rc) - ranging completeinit(d) - dhcp request receivedinit

40、(i) - dhcp reply received; IP address assignedinit(t) - TOD request received.init(o) - TFTP request was received.online - modem registered, enabled for dataonline(d) - modem registered, but network access for the CM is disabledonline(pk) - modem registered, BPI enabled and KEK assignedonline(pt) - m

41、odem registered, BPI enabled and TEK assignedreject(m) - modem did attempt to register; registration was refused due to bad micreject(c) - modem did attempt to register; registration was refused due to bad COSreject(pk) - KEK modem key assignment rejectedreject(pt) - TEK modem key assignment rejecte

42、d“Show Cable Modem” State command DefinedDOCSIS Protocol and Signal Sequence54Cisco Systems ConfidentialDOCSIS Protocol and Signal Sequence“T” Timers DefinedT1A CM timing parameter referenced as “Wait for UCD timeout” and having a duration of five UCD maximum time intervals (approximately 10 seconds

43、).T2A CM timing parameter referenced as “Wait for broadcast ranging timeout” and having a duration of five ranging intervals (approximately 10 seconds).T3A CM timing parameter referenced as “Wait for ranging response” and having a duration of between 50 and 200 msec (default 200 msec).T4A CM timing

44、parameter referenced as “Wait for unicast ranging opportunity” If the pending-till-complete field was used earlier by this modem, then the value of the field must be added to this interval. The maximum value is 30 seconds.T5A CMTS timing parameter referenced as “Wait for upstream channel change resp

45、onse” and having a maximum interval of 2 seconds. T6A CM timing parameter referenced as “Wait for registration response” and having maximum interval of 2 seconds.55Cisco Systems ConfidentialFlap List ExplainedMAC addrIdentifies subscriberCable IFPhysical port identifierIns# of times in 180 seconds t

46、hat the modem re-starts initialranging.Hit# of times CMTS sent a station maintenance message andreceived a response.Miss# of times CMTS sent a station maintenance message anddidnt receive a response.CRC# of CRC errors from that modem.P-Adj# of times CMTS told CM to adjust TX power more than 3dBFlapAlgorithm based on P-Adj and InsTimeMost recent time that the modem dropped off the systemUniversal Broadband Router Overview