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Introduction to Cable-Based Internet Access

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Introduction to Cable-Based Internet Access Powered By Docstoc
					                     SPL-130
                     2905_05_2001_c1   © 2001, Cisco Systems, Inc. All rights reserved.   1




Copyright © 2001, Cisco Systems, Inc. All rights reserved. Printed in USA.
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                                       Introduction to Cable-Based
                                             Internet Access
                                                                                          Session SPL-130




                     SPL-130
                     2905_05_2001_c1   © 2001, Cisco Systems, Inc. All rights reserved.                     3




                           Agenda



                                                                        • DOCSIS Overview
                                                                        • Introduction to RF
                                                                        • CMTS Products
                                                                        • Lab Configuration
                                                                        • Modem Initialization


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                           Cable Evolution

                          • 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

                                                                                                Cable Serving Area

                                                               HFC                                       > 2000 Homes

                                                                                          N
                                                                    Fiber                                     Coax
                                 Head-End

                                                    Typically Fewer than Five Amplifiers in Cascade
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                           Cable Plant Components

                                                                                                Node   Node    Node
                                                                                                                         uBR

                                                                                                                                   Lifetime
                                                                                                                                   Lifetime
                                                                                                Hub            Broadband             VH-1
                                                                                                                                      VH-1
                                                                                                                                Packetized Data
                                                                                                                                Packetized Data
                                                                                                                 Router              NICK
                                                                                                                                     NICK
                                                                                                                                       E!
                                                                                                                                       E!
                                                                              Head-End                                Node

                               PSTN                                                                Hub          Node
                                                                                                                       COAX
                                                                                                                                  Tap
                                                                                          Hub                 Node
                                            Internet

                                                                                                                               Drop
                                              Node            Node            Node
                                                                                                  Cable Modem
                                                                                                           PC
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                           DOCSIS Overview


                             • DOCSIS is a consortium of ATT, Comcast,
                               Cox, AOL/Time Warner, Rogers,
                               MediaOne, and CableLabs
                             • DOCSIS is a standard supporting DS
                               modulations of QAM 64 and QAM 256, DS
                               FEC of Annex B, US modulations of QPSK
                               and QAM 16, in-band control channels,
                               MPEG framing, and RSA key distribution

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                           DOCSIS Overview


                                               TDMA                        Freq
                                                                            Freq    Channel
                                                                                    Channel     Band
                                                                                                Band     Raw Bit
                                                                                                         Raw Bit   Payload
                                                                                                                   Payload
                                               Carrier                   Range MHz Width MHz. Rate MSps Rate Mbps Rate Mbps
                                                                         Range MHz Width MHz. Rate MSps Rate Mbps Rate Mbps

                                                                             54–860       6     5.3605   42.88       38
                                             QAM-256
                                             8 b/Sym                         54–860       8      7.15     57.2      51

                                             QAM-64                          54–860       6     5.057    30.34      27
                                             6 b/Sym                         54–860       8      6.74    40.44      36
                                             QAM-16                           5–42        1.6    1.28     5.12      4.6
                                             4 b/Sym                          5–42        3.2    2.56    10.24       9
                                              QPSK                             5–42       1.6    1.28     2.56      2.3
                                              2 b/Sym                          5–42       3.2    2.56     5.12      4.6




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                           RF Spectrum
                                          110/220 V                                   Frequency Spectrum
                                          Electrical
                                          Signal     CB                                 Channel 2
                                          60 Hz      27 MHz                             55 MHz
                                                                                                    Satellite                                                            Frequency

                                            IF
                                            IF    RF (VHF and UHF) Microwave Infrared Visible Ultra X-Rays
                                                  RF (VHF and UHF) Microwave          Visible                                                                            Gamma
                                         5–45 MHz
                                         5–45 MHz     55–750 MHz Above 1 GHz
                                                      55–750 MHz Above 1 GHz           Light Violet
                                                                                       Light                                                                              Rays



                                                                             • Radio Freq (RF)
                                                                                             Above audio to infrared
                                                                             • Down Stream (DS)
                                                                                             Cable company to subscriber
                                                                                             55–750 MHz
                                                                             • Up Stream (US)
                                                                                             Subscriber to cable company
                                                                                             5–42 MHz
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                           Frequency Allocation
                                                                                                             Astronomy                                                 Air Traffic
                                                      CB HAM                          HAM                  Aero Navigation                                              Control 136     MHZ
                                         Short Wave             Land Mobile                                                                    Aero Navigation                     HAM
                                                              Radio and Paging               TV Channels       TV Channels        FM                                  Research
                       Over Air             Ham                                                  2–4               5–6                            Aircraft Voice                   Other
                         Cable                                                               2                          6        A-6                 A–1    A                             E
                                         5.75                                        50 - 54            72 76           88                 108             (14)                        (18) 150
                                                                                                 Telemetry HAM
                                            Land         Gov’t
                                          Maritime       Fixed               TV Channels 7–13                          Gov’t Fixed Mobile Including Aero Communications
                        Over Air           Mobile        Mobile
                          Cable      F                            I      7                         13      K                                                                              W
                                   150 (19)                                                                                                                                           (36) 300
                                                                                                                             6         (MHZ)


                                          Harbor Navigation                    Aero                                                            Research      Land
                                                                             Navigation                    Gov’t Fixed Mobile                   Other        Mobile          HAM
                      Over Air              Coast Guard
                        Cable       AA                                                                                                                                                   YY
                                    300(37)                                                                                                                                           (61) 450


                      Over Air           Land Mobile                  UHF TV Channels 14–20                                      UHF
                        Cable
                                     ZZ 63                                                                                                                                               86

                                   450                                                                                                                                                    600
                       Over Air                    Various Services
                         Cable
                                         87                  116 117                 158                                     Trouble Area for CATV
                                   600                           750                   1000
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                           Coaxial Cable Transmission Systems



                            • Cable TV fundamental unit of measurement:
                                       (dBmV) decibel-millivolt
                                       with reference of:
                                       0 dBmV = 1 millivolt measured across impedance of 75 ohms
                                               = 1/1000 volt measured across impedance of 75 ohm
                                               = .001 volt measured across impedance of 75 ohm
                                               = 10-3 volt measured across impedance of 75 ohm




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                           Basic RF and Multiplexing Concepts

                                              • Multiplexing
                                                             TDM (Time Division Multiplexing)
                                                             TDMA (Time Division Multiple Access)
                                                             FDM (Frequency Division Multiplexing)
                                              • Modulation
                                                             QPSK (Quadrature Phase Shift Keying)
                                                             QAM (Quadrature Amplitude Modulation)
                                              • FEC (Forward Error Correction)
                                                             (Reed Solomon Coding Algorithm)

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                           Types of Multiplexing

                                                                                          Slow Bit Stream 1
                              • TDM                                                                                TDM Signal

                                         Sharing time on                                                Time       Fast Bit Stream
                                         the same media                                   Slow Bit Stream 2

                                         Frame relay is TDM                                                                      Time
                                                                                                        Time
                              • FDM
                                                                                          Signal 1                 FDM Signal
                                         Sharing freq spectrum
                                         on the same media                                           Frequency     Modulated Signal
                                                                                          Signal 2
                                         Video over cable
                                         is FDM                                                                             Frequency
                                                                                                     Frequency



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                           DOCSIS Modulation Modes



                                                                                                       .      ..   .    .
                                  • Downstream:                                                        .      .    .    .
                                                64 QAM; 256 QAM                                         .      .   .    .
                                                                                                        .      .   .    .
                                  • Upstream:
                                                QPSK; 16 QAM
                                                                                                 16 QAM Constellation




                     SPL-130
                     2905_05_2001_c1   © 2001, Cisco Systems, Inc. All rights reserved.                                               14




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                           Composite Downstream Spectrum

                                                      Amplitude
                                                      dBmV                           Multiple NTSC Channels
                                              0

                                           -10
                                                                       Video                                  Video
                                           -20                                             Down Stream
                                                                                            QAM Data
                                           -30

                                           -40

                                           -50
                                                                       6.0 MHz                6.0 MHz     6.0 MHz

                                                                                                              Frequency MHz



                                                • QAM
                                                              Quadrature Amplitude Modulation

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                           Head-End RF Levels

                                          • IF downstream +32 dBmV +/- 2 dB
                                          • RF downstream +55 to +58 dBmV
                                                         As per upconverter specs

                                          • RF Upstream 0 dBmV nominal
                                                         Head-end commands modems until
                                                         nominal level is reached
                                                         Nominal level adjustable –10 dBmV
                                                         to +10 dBmV

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                           Spectrum Analyzers
                           Required for Installation




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                           Upstream Impairments


                            • Ingress noise                                               • Amateur, shortwave,
                                                                                            CB radio, bad
                            • Impulse noise                                                 grounding and
                            • Reflections                                                   connections

                            • Laser clipping                                              • Power line arcing,
                                                                                            bad grounding and
                            • Common path                                                   connections
                              distortion
                                                                                          • Unterminated drops
                            • Corroded connections
                                                                                          • Misaligned amplifiers,
                                                                                            contention intervals

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                           Common Networking Problems

                                             • Noise
                                                            Unwanted signals
                                                            RF amplifiers introduce noise
                                                            Electrical and Magnetic Interference (EMI)
                                                            Thermal noise
                                                            C/N—measure of video quality
                                             • Co–channel
                                                            Ingress due to other channels appearing
                                                            at the desired channel frequency
                                             • Ingress
                                                            Interference of leaking signals
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                           Need for Service Classes (COS)


                            • Different service levels enable different pricing
                              plans for the individual subscribers based on the
                              type of applications they will be running
                            • MSO has policing capability against misbehaving
                              users; no single CM can monopolize available
                              channel bandwidth resource
                            • Advanced QoS enables real-time and non
                              real-time traffic to coexist on the same channel


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                           uBR Product Positioning
                                 Performance and Density
                                                            Robust Functionality
                                                                                   Large MSO/ISPs
                                                                                                                                 uBR10012
                                                                                                                 uBR7246-VXR
                                                                                   Medium/Large MSO/ISPs
                                                                                                              uBR7246
                                                                                             uBR7223
                                                                                   Small MSO/ISPs
                                                            Medium




                                                                                    uBR7100

                                                                                     Small                                          Large
                                                                                                              MSO Network Size


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                           uBR7100

                             • Cost effective CMTS for MDUs
                               and small HFC plants
                             • Compact 2RU package NPE-175
                               equivalent motherboard
                             • Fixed configuration MC11
                               line card
                             • One single wide port adapter
                               100% uBR7200 SW compatible
                             • Optional integrated upconverter
                             • Optional national clock module
                             • Optional redundant power
                               supply
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                           uBR7246 Hardware Overview



                                                • Commonalities with Cisco 7200
                                                • CPU card—NPE200,300,400
                                                • I/O card—MII or RJ45 FE port
                                                • 2 PA slots



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                           uBR7246 Chassis (Front)
                         FE MII                                                                                Port Adapter Slots


                        PCMCIA
                                                                                                                                I/O Card
                          Flash
                          Cards
                                                                                                                                Console

                                 8E                                                                                             Aux
                         Installed
                           in Left
                                Slot                                                                                            4 Line
                                                                                                                                Card
                                                                                                                                Slots


                        Fan Tray


                                                        LEDs                               Upstream     MC11      Downstream
                                                                                          F Connector             F Connector
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                           uBR7246 Chassis (Back)

                           NPE
                         200/30
                          0/400




                                                                                                                                2 Power
                                                                                                                                Supply
                                                                                                                                Slots




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                           UBR 7246

                                                                                          Networking Processing Engine
                                                                                    NPE-200,300,400 (128 MB DRAM)
                                                                                   + Dram + Flash + In/Out Controller


                            CORE Common Equipment + POWER Option, Etc..



                               Port Adaptors (QTY 2)
                               PA— ATM 100 OC -3 Rate Interface
                               PA— ATM 100 OC -3 Rate Interface
                               PA— 4E (Four IEEE 802.3 10 Base T Ethernet)
                               PA— 4E (Four IEEE 802.3 10 Base T Ethernet)
                               PA— 8E (Eight IEEE 802.3 10 Base T Ethernet)
                               PA— 8E (Eight IEEE 802.3 10 Base T Ethernet)                                         uBR Modem Cards
                               PA—FE- TX (100 Base T Fast Ethernet e/w RJ-45)
                               PA—FE- TX (100 Base T Fast Ethernet e/w RJ-45)
                                                                                                                         uBR-MC1x1
                               PA—FE-FX (100 Base T Fast Ethernet e/w SC Optical Connector)
                               PA—FE-FX (100 Base T Fast Ethernet e/w SC Optical Connector)
                               DPT, Optical, Gigabit
                               DPT, Optical, Gigabit                                                                     uBR-MC1x6
                                                  + Service Adapter Cables
                                                  + Service Adapter Cables                                               uBR-MC2x8
                                                  + Software and License
                                                  + Software and License
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                           uBR10012 Series High-End
                           Broadband Router

                            • Highly scalable
                              architecture
                            • Optimized for aggregation
                            • Industry leading capacity,
                              performance and reliability
                            • Extension of 10000ESR
                              technology
                            • Investment protection
                            • Proven Cisco technology


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                           uBR10012—Components
                                           Blower Assembly                                                    Power Modules

                           RF Line Cards                                                         Display Module


                                                                                          Utility Cards




                                                                                           LAN/WAN
                                                                                           Line Cards



                                                                                          Performance
                                                                                               Routing
                                                                                               Engines
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                           uBR10012—System Features
                          •   System cards
                                       Full card level redundancy with hot swap
                                       Specialized card types for optimal density
                                       and performance
                          •   System interconnect
                                       Reliable fully passive midplane
                                       Speed independent point-to-point data
                                       path
                                       Dedicated control plane interface                            31.5”
                                                                                                    31.5”
                                       Dedicated redundancy state comm link
                          •   Power system
                                       Dual redundant, load sharing power
                                       modules
                                       DC and AC power options
                                       48 volt power distribution with local
                                       conversion                                                   23”
                                                                                                    23”
                          •   Cooling system
                                       Front-to-back, bottom-to-top airflow                 17.5”
                                                                                            17.5”
                                       Modular, variable speed blower assembly
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                           Parts Required for 6’ Installation

                                                                • uBR
                                                                • Upconverter
                                                                • Cable modem(s)
                                                                • Coax (8–12 pieces)
                                                                • Diplex filter
                                                                • Splitters
                                                                • Attenuator pads
                                                                • DHCP/TOD/TFTP servers
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                           6’ Plant Block Diagram

                                       uBR7246
                                                                                                                 Upconverter
                                                                                    Servers


                                                                                                IF In


                                                                                                              RF Out
                                                                                                               2@ 20 dB Pad          Modems


                                                                                                        Hi
                                                                                                                            -7 dB
                                                                                 Diplex Filter
                                                                                                         Lo     Common
                                                                                                                     4 Way Splitter
                                                                          2@ 20 dB Pad
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                           1+1 Redundant Configuration

                                                                                                 IP Cloud

                                                                                                         Aggregate Router

                                                                Standby                                              Active
                                                              CMTS Router                                          CMTS Router




                                                                                                                              IF Upconverter
                                                                                                                              w/ SNMP



                                                   Splitter                                                  Combiner



                                                                                          HFC
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                           Required Servers for DOCSIS

                                • DHCP (Dynamic Host Configuration
                                  Protocol)
                                            Provides IP addresses for modems and PCs

                                • TOD (Time of Day)
                                            System time clock

                                • TFTP (Trivial File Transfer Protocol)
                                            Modem configuration files


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                           Cisco Network Registrar Overview

                              • Cisco Network Registrar provides
                                integrated DHCP and DNS services
                              • Can also integrate ToD server and TFTP
                                server (depending on size of network)
                              • Provides DHCP safe failover and dynamic
                                DNS updates (notify and IXFR)
                              • Provides enhancements specific
                                for cable networks

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                           Cisco Network Registrar in Head-End


                                                                                                                                                 Internet




                            DHCP/DNS                        TFTP                          Security   Cable Modem      Remote        Routers,
                         Network Registrar                  Server                         Server     Termination     Access          Etc.
                                                                                                     System Rack      Server
                                                                                                                       Rack




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                           Cable Modem Initialization



                                       Head End Interface                                                             Cable Modem
                                   Clock Synch B’cast                                                                       Scan DS for QAM
                                   (One per 1.63 msec)
                                   (One per 1.63 msec)                                                                         Wait for Clock Synch
                                                                                                                               Wait for Clock Synch
                                                                                                                                Set Signaling Clock
                                                                                                                                Set Signaling Clock
                                  UCD B’cast
                                  US Channel Descriptor,
                                  US Channel Descriptor,                                                                           Wait for UCD
                                                                                                                                   Wait for UCD
                                  DS Channel ID and Minislot Size
                                  DS Channel ID and Minislot Size                                                      Set US Channel Frequency
                                                                                                                       Set US Channel Frequency
                                  (One per Second per US Channel)
                                  (One per Second per US Channel)
                                  MAP B’cast                                                                                         Wait for MAP
                                                                                                                                     Wait for MAP
                                  Contains US Time Sharing Information
                                  Contains US Time Sharing Information                                              Look for Shared Request Slots
                                                                                                                    Look for Shared Request Slots
                                  (One per 4 ms per US Channel)
                                  (One per 4 ms per US Channel)                                                       (Available Every 2 Seconds)
                                                                                                                      (Available Every 2 Seconds)




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                           Cable Modem Initialization

                                         Head End Interface                                                 Cable Modem
                                 Ranging Response                                                                Ranging Response
                                 (Can Be Sent as Needed)
                                 (Can Be Sent as Needed)                                                    Only in Shared Request Slots
                                                                                                            Only in Shared Request Slots
                                 US/DS Frequency Can Be Changed
                                 US/DS Frequency Can Be Changed                                                  Use USE = 0 (Service ID)
                                                                                                                 Use USE = 0 (Service ID)
                                 Contains Temp SID
                                 Contains Temp SID
                                           Fails if No/Bad US
                                           Fails if No/Bad US                                                  Wait for Ranging Response
                                                                                                               Wait for Ranging Response
                                           Or Too Many Modems
                                           Or Too Many Modems                                               Adjust Clock (in 6.25 US Ticks)
                                                                                                            Adjust Clock (in 6.25 US Ticks)
                                                                                                           Adjust Power (in 0.25 dB Steps)
                                                                                                           Adjust Power (in 0.25 dB Steps)
                                   Keep Alive
                                   (One per 30 Second per Modem)
                                   (One per 30 Second per Modem)                                                    Wait for 1st Keep Alive
                                                                                                                    Wait for 1st Keep Alive
                                                                                                                    Ranging Request
                                  Ranging Response
                                                                                                                         Now in Allocated
                                                                                                                         Now in Allocated
                                  (Can Be Sent As Needed)
                                  (Can Be Sent As Needed)
                                  US/DS Frequency Can Be Changed)
                                  US/DS Frequency Can Be Changed)                                                        Maintenance Slot
                                                                                                                         Maintenance Slot

                                                                                           Link Establishment
                                        (Cable Modem HFC Interface Line Protocol Up, Not Online Yet)
                                              Maintain Station Link Using Periodic Keep Alives
                                                   Link Broken if Missed 16 Keep Alives

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                           Cable Modem Initialization


                                        Head End Interface                                                  Cable Modem
                                       Map B’Cast                                                               Bandwidth Request
                                       Contains US Time Sharing Info
                                       Contains US Time Sharing Info                                       Only in Shared Request Slots
                                                                                                           Only in Shared Request Slots
                                       (One per Four ms per US Channel
                                       (One per Four ms per US Channel                                        Use Temp SID (Service ID)
                                                                                                              Use Temp SID (Service ID)
                                                                                                           (Needed for Every Use of US)
                                                                                                           (Needed for Every Use of US)
                                       DHCP Response
                                       Contains ID Addr, Default GW, ToD
                                       Contains ID Addr, Default GW, ToD                                              DHCP Request
                                       Server, TFTP Server Addr and TFTP
                                       Server, TFTP Server Addr and TFTP
                                                                                                                  Now in Allocated Slots
                                                                                                                  Now in Allocated Slots
                                       Boot Config File Name
                                       Boot Config File Name
                                       From a DHCP Server
                                       From a DHCP Server

                                       ToD Response
                                       Contains Time of Day
                                                                                                                      ToD Response
                                       Contains Time of Day
                                                                                                                  Now in Allocated Slots
                                                                                                                  Now in Allocated Slots
                                       RFC 868, not NTP
                                       RFC 868, not NTP
                                       From a ToD Server
                                       From a ToD Server




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                           Cable Modem Initialization

                                         Head End Interface                                        Cable Modem
                                  TFTP Boot File Transfer                                           TFTP Boot Request
                                  Contains QoS Parameters
                                  Contains QoS Parameters                                          Send TFTP Boot File Name
                                                                                                   Send TFTP Boot File Name
                                  Specifies Privacy, New Software
                                  Specifies Privacy, New Software                                     Now in Allocated Slots
                                                                                                      Now in Allocated Slots
                                  Downloads, Etc.
                                  Downloads, Etc.
                                  From an TFTP Server
                                  From an TFTP Server

                                  Registration Response                                            Registration Request
                                  Contains Assigned SID
                                  Contains Assigned SID                                               Send QoS Parameters
                                                                                                       Send QoS Parameters
                                  Modem Registered
                                  Modem Registered
                                                                                                      Now in Allocated Slots
                                                                                                      Now in Allocated Slots
                                    Fail if QoS Not Available
                                    Fail if QoS Not Available
                                    Or Authentication Failed
                                    Or Authentication Failed

                                                                                    Cable Modem Online
                                                 Maintain Station Link Using Periodic Keep Alives
                                       May Need to Hop Upstream Frequency Due to Noise (Means Link Reset)



                     SPL-130
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                           Where to Go for More Info


                                • http://www.scte.org/
                                • http://www.cable-modem.net/
                                • http://www.cablemodem.com/
                                  specifications.html
                                • http://www.cisco.com/warp/customer/44/
                                  solutions/network/cable.shtml


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                                       Introduction to Cable-Based
                                             Internet Access
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                     SPL-130
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