CISC452-00W Telecommunications Systems

Transcription

1 CISC452-00W Telecommunications Systems Lesson 2 Residential Broadband Slides courtesy Cisco Systems 1

2 Defining DSL: Digital Subscriber Loop Customer DSL Modem DSL Copper Loop DSL Modem Value-Added Packet Network Like dial, cable, wireless, and T1, DSL is a Transmission Technology, NOT a full end-to-end solution Users don t buy DSL, they buy services, such as high-speed Internet, leased line, VPN, and Video on Demand 2

3 DSL Modem Technology DSL Service Max. Data Rate Down/Uplink (bps) Line Coding Technology Analog Voice Support Max. Reach (km-feet) VDSL Very High Bit Rate DSL 25M/1.6M or 8M/8M??? Yes.9 3,000 ADSL Asymmetric DSL 8M/1M CAP & DMT Yes ,000 IDSL ISDN DSL 144K/144K 2B1Q No ,000 SDSL Symmetric DSL 768K/768K 2B1Q / CAP No ,000 Residential SOHO HDSL2 High Bit Rate DSL 1.5M 2.0M/ 1.5M 2.0M Optis No ,000 Business Trade-off is Reach vs. Bandwidth Reach numbers imply Clean Copper Different layer 1 transmission technologies, need a common upper protocol layer to tie them together 3

4 RADSL (Rate Adaptive ADSL) Mass deployment technology Good Reach Preserves Baseband POTS Rate adjusts to local loop conditions Good Spectral Compatibility Competing line code variations - CAP, DMT, G.Lite 4

5 Carrierless Amplitude and Phase One Supplier (GlobeSpan) POTS Upstream Downstream Utilizes CAP encoding within upstream and downstream multiplexed carriers Rate adapts by modifying #bits/cycle (Constellation size) + Carrier baud rate 136 khz 136 khz 340 khz 680 khz 952 khz 1080 khz 4 khz f1 f2 5

6 Discrete Multi-Tone ANSI T1.413 Standard for ADSL Multiple Suppliers Utilizes QAM line code within many multiplexed bands or tones Rate adapts by changing or zeroing-out bits/tone POTS Upstream 4 khz f1 f2 Downstream 6

7 G.Lite Sub-rate (<1.5Mbps), splitterless, consumeroriented standard Promoted by UAWG (Intel, Microsoft, Compaq) Based on DMT standard (lower 128 tones) Should interoperate with full-rate DMT (g.hs used to signal at startup) Targeted for 1H 1999 POTS Upstream 4 khz f1 f2 Downstream 7

8 Frequency Spectrum Utilization 0 Transmit Power Spectra ISDN 2B1Q RADSL Upstream RADSL Downstream (1088 baud) 40 PSD (dbm/hz) HDSL 2B1Q T1 AMI frequency (khz) 8

9 Crosstalk Customer Upstream DSL Modem Downstream DSLAM Downstream power is highest at the DSLAM and lowest at the CPE. Upstream power is lowest at the DSLAM and highest at the CPE. If these signals are in different frequency spectrums then they will not crosstalk, otherwise there will be interference from one signal to the other. 9

10 Crosstalk - ADSL and T1 Customer DSL Modem Upstream Repeated T1 DSLAM Downstream Downstream power is highest at the DSLAM and lowest at the CPE. Upstream power is lowest at the DSLAM and highest at the CPE. If these signals are in different frequency spectrums then they will not crosstalk, otherwise there will be interference from one signal to the other. 10

11 ATM over xdsl Multiple connection multiplexing Built in QoS / CoS for newer services ATM DSL Transmission Technology 11

12 IDSL Legacy CPE requires that the access link use HDLC or Frame links. ITU-C on DSLAM will interwork from Frame to ATM HDLC / Frame DSL Transmission Technology 12

13 ADSL Terminology ATU-C: ADSL Transmission Unit, Central The ADSL point of termination in the central office An ADSL modem ATU-R: ADSL Transmission Unit, Remote The remote user s ADSL modem The CPE DSLAM: DSL Access Multiplexer Central office device that concentrates many ADSL connections into one DSLAM contains ATU-Cs 13

14 End-to-End ADSL Architecture PSTN ATU-R DSLAM IP IP ATM/ Frame Relay Network ISP ISP Local Loop ATU-R L2/L3 Services Aggregator Central Office UCP Broadband Network Corporate Content Providers

15 ADSL Data Bypass CPE SMB/SOHO Central Office POTS Splitter ADSL MDF L2/L3 Engine Residential POTS Splitter ADSL Splitter DSLAM Content Providers Copper Loop

16 Classic VPN ATM-to-ATM Solution ATM PVC ATM Ethernet Protocol Transparency VC between CPE router and ISP central router Multiple QoS classes and guaranteed levels of QoS IP services mapped over ATM 16

17 PPP over ATM over ADSL with L2TP Tunnel ATU-R Aggregator L2TP Tunnel PPP/ATM ATM PPP/L2TP AAA DNS/DHCP Server Server Essential operational functions can be delivered using well established features in PPP/L2TP, such as: Authentication (PAP, CHAP, etc.) Address Administration done at the service provider gateway Layer 3 autoconfig (DHCP, DNS, etc.) Dynamic Selection of Multiple Destinations (via multiple PPP Sessions) Encryption 17

18 Generic xdsl Implementation Central Office Telephone Switch Remote Location Corporation or ISP Data Network xdsl Modem Splitter POTS Single Pair Telephone Line xdsl Modem An Access Solution: Connects Remote User to Central Office as a Dedicated Circuit 18

19 ADSL Voice Network Data Network Advantages DSLAM (ATU-C) Splitter MDF Date rate Uses in-place copper loops POTS on same line Reduces load on C.O. switch Emerging as the standard Splitter xdsl Modem 8 Mbps > < 640 Kbps Disadvantages Expensive modems, today Speed/distance trade-off 19

20 Connectivity, ADSL Voice Network Cells DSLAM Cells The ADSL Reference Model DMT modems and a dumb DSLAM Ethernet or ATM25 to the desktop Cells to the CPE Cells to the backhaul network 1577 IP over ATM 20

21 Connectivity, ADSL Voice Network Ethernet Frames Cells Frames Today s Reality Standalone ATU-Cs (modems) Switches and/or routers for aggregation Bridged Ethernet to the desktop 1483 encapsulation One PVC per user to the backhaul network 21

22 Connectivity, ADSL Voice Network Cells Packet Frame Relay Ethernet Frames What It will Evolve to Ethernet frames or cells to the desktop 1483, PPP over ATM, or 1577 connectivity Cell, Frame Relay, or packet backhaul Traffic shaping, per user Layer 3 service in the C.O. 22

23 HDSL/SDSL Data Network Advantages HDSL/SDSL Modems Proven technology Uses in-place copper loops Reduces load on C.O. switch MDF <> 2 MB Disadvantages HDSL/SDSL Modem Two MB maximum data rate POTS requires second line Few vendor choices 23

24 IDSL Voice Network Data Network Advantages MDF POTS <>128 Kbps ISDN T/A Disadvantages Reduces load on C.O. switch Limited data rate Uses standard ISDN equipment Second line for POTS Inexpensive to deploy 24

25 VDSL Data Network SONET < 52 MB 2 MB > VDSL Modem Advantages Enormous data rate Uses in-place copper loops Avoids C.O. switch Disadvantages No standards Limited ongoing development Unavailable Short distance limit 25

26 Connection Variables Destination Backbone Central Office Remote Corporation xdsl ISP Network service definition has significant effect on data connection How many destinations? 1 or N? Simple connectivity or value-added service? Cells to the user or frames? Flat-rate billing or usage based? 26

27 Power Branch Small- Medium Enterprise Residential Telecommuter Building End-to-End Networks and Services Cisco 2500/2600/ x/633 VoIP Cisco 140x/1600/1700 Cisco 67x Cisco 62x Cisco 77x/1004/1604 Cisco 60x S p l i t t e r Cisco DLC Cisco AS5300 Cisco 6xxx Cisco 90i DSL PoP V POTS/PSTN SSG Cisco 6400 CCE IP/TV TIBCO CPC Circuit Core Cisco BPX Core Cisco GSR Core Cisco 3600, 7200, 6400 ISPs Corporate Government U N I V E R S I T Y Education 27

28 The Future for xdsl How many systems will be upgraded to DSL for POTS service? How many Loops qualify? How popular will competing technologies become? How will ISP s price higher Internet services? Is there a market for access networks that can provide multiple services? 28

29 Cable Network Pre World War II The concept of television is born! Competing and divergent views on implementation methods promoted by several sources 29

30 Cable Network Post World War II Television becomes a reality! Television transmitters established: Limited content Few broadcast sources Limited urban coverage, or near rural transmitters 30

31 Cable Network A+B+C B A+C A+B A A+B+C Few sources Blockage B+C C Limited content Limited reach Excellent to Poor Picture Quality Reception Signal blockage

32 Cable Network A+B+C B A+C A+B A A+B+C Blockage B+C C The Community Antenna circa 1948 Few sources Limited content Excellent to Poor Picture Quality Reception

33 Cable Network Introduction of the Community Antenna! Makes video available to many Improves signal quality Extended coverage through amplification Amplification has range limitations because of excessive noise 33

34 Cable Network CATV as we know it is born: But! One way broadcast signal distribution Signal amplification over coaxial cable Amplifiers powered through coaxial cable plant Range limitation because of noise build up Limited content: Current affairs and panel discussions Little entertainment Reduced broadcast hours Few broadcast/content sources Frequent outages Cable networking advances 34

35 Cable Network SIGNAL From B A ~ 60 km Microwave Path SIGNAL From C Microwave + The Community Antenna Microwave Broadens the Distribution Range of Quality Video Reception to a Larger Subscriber Population

36 Cable Network SIGNAL From B ~ 60 km Microwave Path SIGNAL From C Head End (Basic Networking into the 1990 s) Amplifiers Extend Distribution Signals Distributed to Subscriber Via Tap and Drop Cable 36

37 Cable Network Cable Networking Standards Evolve: Based on available vendor product and cost: Diameter and quality of Coaxial Cable Bandwidth specification on amplifiers Power distribution products Set Top devices Standards primarily defined channel capacity: Initially 16 channels, followed by: 32 channel systems 64 channel systems Limited quality control, faults often identified by customer call 37

38 Cable Network Limited Content and Signal Sources Available: Content sourced from: Local OFF AIR pickup Remote OFF AIR pickup with microwave back haul Film and tape Emerging local content as mandated by FRANCHISE terms: Local affairs, educational etc. Consequently: 16 or 32 channel systems are considered adequate Systems were LOCAL, limited to regional FRANCHISE Owned and Operated by local entrepreneur 38

39 Cable Network Satellite transmission emerges: New content becomes available National coverage by a single source is now possible A national market develops for content producers A CORNUCOPIA of content offered to the market Resulting in: New customer demand for content (HBO, CNN, ESPN, International) New marketing concepts e.g.., Pay Per View, Premium channels Market DEMAND compels CATV operators to: Increase system capacity Improve service quality Invest heavily in their networks, or Cash In and sell out to stronger players The MSO Emerges 39

40 Cable Network PST CNN Hollywood CST EST HBO Satellites Permit: National and Global Coverage More Content, More Sources C I S C O H A L L U N I V E R S I T Y University 40

41 Cable Network Growth Caused By Increased Traffic, Content and Market Demand Results in: Industry consolidation Expansion of MSO holdings TCI TIME WARNER CABLE MEDIA ONE 14 M basic subscribers 7 M basic subscribers 5 M basic subscribers System clustering (property exchanges) 41

42 Cable Network Upgrading the Cable Network: To meet customer service expectations To increase capacity Defend against loss of market share To support new services and revenue growth 42

43 Cable Network Upgrading the Cable Network: Introduce Fiber Optics technology to the network Improve signal quality Reduce maintenance effort and cost Remove bandwidth constraints Reduce operating cost Reduce the number of failure elements HFC (Hybrid Fiber Coax) Is the Result! 19

44 Cable Network > 2000 HOMES Headend Coaxial Cable COAX 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! 44

45 Cable Network HFC Cable Serving Area > 2000 HOMES Headend Fiber N COAX Typically Fewer than Five Amplifiers in Cascade The video signal is transmitted 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 NODE N 45

46 Cable Network Cable Plants Are Upgraded for: Improved reliability Smaller serving area Increased bandwidth Increased availability Improved end-to-end signal quality Advanced network management Two way operation Platform for advanced services 46

47 Cable Network Reliability < 80 Channels CNN HBO ESPN Hub Hub Headend Hub RING architecture Analog fiber RING for broadcast video Headend/hub to improve reliability SONET/SDH RING overlay for reliability of advanced services 47

48 Cable Network Reliability, Increased Access Bandwidth Smaller, robust serving areas: HFC to the node Alternate feed to the node Target nodes of 500 homes Fewer amplifiers Alternate Feed Hub Node Settop TV Node Node COAX < 80 Channels Drop CNN HBO ESPN Tap 48

49 Cable Network < 100 Channels CNN HBO ESPN Increased bandwidth: Downstream rebuilds to 750 MHz Wide band amplifiers etc Two way operation: Upstream (5 42 MHz) Provisioned and Operational H HE Signal Flow H 5 42 MHz MHz N N 49

50 Cable Network TOTAL NETWORK MANAGEMENT Node Node Node Headend Hub Hub Hub Node Node Node COAX < 100 Channels CNN HBO ESPN FNN Tap Node Node Node Settop TV Drop Nodes Tend to 500 Homes

51 Cable Network An Advanced Services Platform Based on DOCSIS (Data Over Cable Services Interface Specifications) enables High Speed Data over Cable 51

52 Cable Network Cisco Universal Broadband Router ubr

53 Cable Network Advanced Services Total Network Management Node Node Node ubr7246 < 100 Channels Hub Broadband Router CNN HBO Headend Node ESPN FNN PSTN Internet Hub Hub Node Node COAX Tap Node Node Node Drop Cable Modem PC

54 Cable Network DOCSIS Standard DATA Platform Usage Rate Per User The Network ubr 7246 Number of Users per Headend Modem MAC Protocol 128kbs TAP 512kbs >1000 >250 QAM/QPSK Modulation Ethernet Port Cable Modem 54

55 Cable Network DOCSIS Standard DATA Platform Offers: High bandwidth QoS (Quality of Service) MPEG packet format Network management Multicast Privacy Security Future capabilities: VoIP (Voice) IP Video 55

56 Cable Network DOCSIS Standard Data Platform Offers: Possible service applications: Internet access Enterprise Telecommute Virtual private network Voice SOHO 56

57 Cable Network Offers New Service Possibilities Government Networking over Cable Enterprise Corporate Telecommute SOHO C I S C O H A L L U N I V E R S I T Y Consumer Academic

58 Upgraded Cable Plant Cable plants are upgraded for: More reliable topology Increased bandwidth/smaller serving areas Increased availability More reliable signal Advanced network management Two way operation Advanced services 58

59 Cable Data Standards MCNS A. Industry-developed spec B. Inexpensive implementation C. Already successful in the marketplace IEEE : wait and see 59

60 Network Services Solutions Subscriber Management Network Provisioning Network Configuration NT and UNIX Network Operating Systems Users and Applications Network Operating System User Profiles Application Privileges Network Service Policies Network Elements Cisco/Microsoft Active Directory Element Configurations Intelligent Directory Services OSPF RSVP IP Multicast Tag Switching L2TP BGP Cisco IOS Encryption other... Network Services

61 Services Analog broadcast video Digital broadcast video Existing Services Internet access: Web, e IP-based services Voice H.323 Webcast video Lower-bandwidth video over IP Video on demand Video conferencing and collaborative applications Radio/music Push services Personalized video and data New Services 9

62 Application Opportunities Latency/ Jitter New 1 Sec 100 Msec Streaming Video On Demand Distance Learning Personalized Internet Data/Video Access Video Video VoIP Broadcasting Conferencing Existing Mb/s Bandwidth per Stream 62

63 Video As Data: Bandwidth Assume 100 video channels Assume 5 Mbps each Total bandwidth only 500 Mbps Less than one OC-12! High end routers and switches have a dozen or more OC-12 ports 63

64 Backbone Structure Fiber Ring H H Primary Head End N N N H Standby Head End (Optional) H H H Hub: K Homes PSTN Internet N Node: Homes 64

65 Separate Infrastructures Benefits Uses existing equipment Problems Duplicate networks Costly Unwieldy, complex Video is not networked, only point-to-point links Video Voice IP Optical Data SONET ATM 65

66 IP Transport Infrastructure Benefits Unified network infrastructure IP brings scale and security IP is ubiquitous QoS w/ RSVP, L3 services Lower cost of ownership Leverage the Internet growth Applications/content/services Cost/performance curve Interoperability Problems Backbone-class devices only emerging now SONET integration New IP-based telephony Video Voice IP SONET++ Optical Data 66

67 Final Backbone Architecture Retains current digital video transmission Simple broadcast It works and it s cheap Uses IP transport for: Switched video Two-way video Complex routes: studios, post production, ad houses, local sources Video Digital Voice IP SONET Optical Data 67

68 Final Backbone Structure Digital Video Transport + SONET++ Ring H H N N H Primary Head End N Standby Head End (Optional) H H H Hub: K Homes PSTN Internet N Node: Homes 68

69 Head End Diagram Satellite Channels PSTN Internet Satellite Receivers Scramblers Descramblers Conditional Access Server Web Cache Server PSTN Gateway/Dia lserver MPEG Encoders Ad Insertion IP/MPEG Re-Muxes Fast Ether/ Gig-Ether High-Speed Router Analog Receivers AM/Digital Video Transport Encoder Hub OC-48 SONET++/ AM or DVT Hub Off Air Channels Hub 17

70 Hub Diagram AM/Digital Video Transport Encoder Modulators AM and Digital Channels RF OC-48 SONET++/ AM or DVT Web Cache Server Fast Ether/Gig- Ether Ad Insertion MCNS Down RF MCNS Up Universal Broadband Router E/O O/E 70

71 Access Network: HFC Analog video on RF Digital video MPEG/64QAM Voice, Web, webcast video IP/MCNS/64QAM Video MPEG Video RF/Optical Voice IP MCNS/ MPEG Web IP Services Digital Video Analog Video 71

72 RF Spectrum Map Frequency MCNS Data Channel(s) Digital Broadcast Channels Analog Broadcast Channels Analog/Digital Set Top w/mcns Data MCNS Data Channel(s) Upstream Two Tuners Select One Video and One MCNS Channel Simultaneously 72

73 Typical Bandwidth per Data User Assumptions: 50% of homes passed are subscribers 10% of subscribers are active One downstream at 64-QAM per 4 fiber nodes One upstream at 2560 Mbps per fiber node HP Per HP Per Peak Data Average Data Node Downstream Rate (D/U) Rate (D/U) Mbps/ 4 Mbps 27 Mbps/ 4 Mbps 270 Kbps/ 102 Kbps 135 Kbps/ 51 Kbps Typical Cost at Head End/Hub Is $5/Home Passed More Bandwidth is Available with More HE Gear 73

74 Residence Network Diagram Ethernet/Voice Cable Modem Ethernet / Voice STB HFC Network Analog Video Digital Video MCNS Data Alternate LANs: Wireless Telco-wired IEEE-1394 USB/Voice Cable Modem 10BaseT HFC Phone 74