Ulllted States Patent
`
`
`Kwok et al.
`
`
`
`[19]
`
`
`
`
`
`
`[11] Patent Number:
`
`
`
`[45] Date of Patent:
`
`
`6,084,876
`
`
`Jul. 4, 2000
`
`US006084876A
`
`
`
`.................... .. 370/397
`
`. . . .. 370/395
`
`
`370/486
`
`
`348/7
`
`
`
`
`
`
`
`
`5/1997 Conscenti et al.
`
`
`
`3/1998 Kwok . . . . . . . . . . . . . .
`
`
`6/1998 Barn et al.
`
`
`
`10/1998 DeR0deff et al.
`
`
`
`BYCIS ........................................
`
`
`
`
`
`Primary Examiner—Seema S. Rao
`Attorney, Agent, or Firm—Lee & Hayes, PLLC
`
`
`
`
`
`
`5,627,836
`
`5,734,652
`
`5,768,279
`
`5,828,403
`
`
`[54] DYNAMIC ATM CONNECTION
`
`
`
`
`MANAGEMENT [N A HYBRID F[BER-C()AX
`
`CABLE NETWORK
`
`
`
`
`
`
`
`Inventors:
`
`
`C. Kwok Kirkland, Yoram
`
`
`
`
`
`
`
`
`Berna» Seamea both of Wash-
`_
`_
`.
`
`
`
`
`
`
`[73] Assignee: Microsoft Corporation, Redmond,
`Wash,
`
`
`.
`[21] Appl' No“ 09/181580
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`
`
`
`
`
`
`[22]
`Filed.
`()et_ 23, 1998
`
`
`
`
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`
`
`Related U_s_ Application Data
`
`[62] Division of application No. 08/639,774, Apr. 29, 1996,
`
`
`
`
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`
`
`
`
`which is a continuation of application No. 08/535,770, Sep~
`
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`
`
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`
`
`27’ 1995’ Pat‘ No‘ 597349652‘
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`
`
`Int. Cl.7 .......................... .. H04N 7/173; H04L 12/56
`[51]
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`
`
`[52] U.S. Cl.
`........................... 370/379; 370/486; 348/5.1;
`
`455/3.1
`[58] Field of Search ..................................... 376/389, 390,
`
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`376/392’ 395’ 396’ 397’ 400’ 409’ 410’
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`485487’ 480; 348/6’ 7’ 10’ 12’ 13’ 16’
`
`
`17; 455/2_5.1
`
`
`[56]
`
`
`
`References Cited
`
`U~S~ PATENT DOCUMENTS
`
`
`
`11/1994 Hoarty et al.
`............................... 348/7
`
`
`
`
`
`2/1995 Look et al.
`348/6
`
`
`
`
`6/1995 Baran ......... ..
`370/395
`11/1996 Sone et al.
`............................ .. 370/397
`
`
`
`
`
`
`
`
`
`5,361,091
`
`5,387,927
`
`5,425,027
`5,577,032
`
`
`
`
`
`[57]
`
`
`
`ABSTRACT
`
`
`
`
`
`
`
`
`
`
`Described herein is an ATM cable network having a plurality
`ofATM subscriber interface units or set-top boxes (STBs) in
`
`
`
`
`
`
`
`
`
`
`
`
`
`individual neighborhood homes.
`coax distribution plant
`provides a plurality of communication channels between the
`
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`
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`
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`
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`STBs and the a neighborhood node. A cable headend serves
`the neighborhood node and its associated STBs through a
`
`
`
`
`
`
`
`fiber-optic trunk providing a plurality of different commu-
`
`
`
`
`
`
`
`nication channels or frequencies. The headend includes an
`
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`ATM node switch having switch ports associated with each
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`of the different commurricatien ehanne1s.A resource men-
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`
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`
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`ager at the headend asslgns 1Ud1V1d11a1 STB5 to TCSPCCUVC
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`
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`
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`
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`communications channels. STBs share both upstream and
`downstream Communfcatlofls Channels and Swltch ports‘ In
`
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`an.extended autoregistration procedure,
`the ATM node
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`switch is configured to assign exclusive ranges of .VPI/VCI
`
`
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`
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`values to the individual STBs tuned to the single switch port.
`During ATM cell transfer, an ATM cell originating from or
`
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`
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`
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`
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`destined to a specific STB uses a VPI/VCI value within the
`range of routing indicators assigned to the STB. This allows
`
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`
`the headend to determine the source of all upstream data
`
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`Cells an a11°W5 STB5 ‘O dlsregard any Cells I10‘ mended f0‘
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`
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`‘hem
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`3 Claims, 4 Drawing Sheets
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`HEADEND
`
`
`TO OTHER NODES
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`
`
`Netflix, Inc. Exhibit 1024
`
`Netflix, Inc. Exhibit 1024
`
`

`
`
`U.S. Patent
`
`
`
`Jul. 4,2000
`
`
`
`
`Sheet 1 of4
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`
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`6,084,876
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`
`
`Netflix, Inc. Exhibit 1024
`
`Netflix, Inc. Exhibit 1024
`
`

`
`U.S. Patent
`
`Jul. 4,2000
`
`Sheet 2 of4
`
`6,084,876
`
` HEADEND
`
`
`
`TOOTHERNODES
`
`32
`
`T0EXTERNALNE7W0f?K
`
`52
`
`SERVERS
`
`90
`VI‘
`
`Netflix, Inc. Exhibit 1024
`
`Netflix, Inc. Exhibit 1024
`
`

`
`
`U.S. Patent
`
`
`
`Jul. 4,2000
`
`
`
`Sheet 3 of4
`
`
`6,084,876
`
`
`
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`FROM HEADEND
`
`
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`REC/DE-MOD
`
`FROM HEADEND
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`REC/DI:-MOD
`
`
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`7
`
`T0 HEADEND
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`CONTROLLER
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`700 702
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`CALL SETUP
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`DATA TRANSFER
`
`
`
`706
`
`
`
`Netflix, Inc. Exhibit 1024
`
`Netflix, Inc. Exhibit 1024
`
`

`
`
`
`U.S. Patent
`
`
`
`Jul. 4, 2000
`
`
`Sheet 4 of4
`
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`6,084,876
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`CONNEC T/NG S TBS
`
`
`
`7 70
`
`
`
`TRANSFERR/NG REG/S TRA T/ON REOUES TS
`
`
`
`
`
`
`
`
`772
`
`
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`SENDING NETWORK ADDRESSES
`
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`SENDING COMB/NED ADDRESSES
`
`SENDING REG/S TRA T/ON ACKNOWLEDGEMENTS
`
`
`
`
`
`774
`
`
`
`
`
`776
`
`
`
`
`
`778
`
`
`
`
`
`7 20
`
`
`
`Netflix, Inc. Exhibit 1024
`
`
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`UPDA T/NG ADDRESS TABLE
`
`
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`
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`jg/6%
`
`Netflix, Inc. Exhibit 1024
`
`

`
`6,084,876
`
`1
`
`DYNAMIC ATM CONNECTION
`
`
`
`MANAGEMENT IN A HYBRID FIBER-COAX
`
`
`
`CABLE NETWORK
`
`
`RELATED APPLICATIONS
`
`
`
`This is a divisional of U.S. patent application Ser. No.
`
`
`
`
`
`
`
`
`08/639,774, filed Apr. 29, 1996, which is now pending
`
`
`
`
`
`
`
`
`which is a continuation of U.S. application Ser. No. 08/535,
`
`
`
`
`
`
`
`770 filing date Sep. 27, 1995, now U.S. Pat. No. 5,734,652.
`
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`TECHNICAL FIELD
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`10
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`This invention relates to public switched broadband cable
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`distribution systems which use ATM (asynchronous transfer
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`mode) for information transfer.
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`BACKGROUND OF THE INVENTION
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`FIG. 1 shows a traditional broadcast CATV (cable
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`television) system, generally designated by the reference
`numeral 10. CATV system 10 includes a headend 12 which
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`is responsible for broadcasting analog video to all subscrib-
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`ers connected to the system. A headend might support from
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`a few hundred homes in a rural area to hundreds of thou-
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`sands of homes in a metropolitan area. Headend 12 is
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`connected to multiple neighborhood nodes 14 by trunk lines
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`16. Traditional
`trunk lines include microwave links and
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`coaxial cables, often associated with repeaters 17. Each
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`neighborhood node serves the homes of a limited neighbor-
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`hood area. In many traditional systems, however, neighbor-
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`hood nodes might each serve several thousand homes.
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`From the neighborhood nodes, connections to homes are
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`made through coaxial plants 18. A coaxial plant comprises
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`multiple active coaxial feeders 19, each tapped by multiple
`passive coaxial drop cables that reach individual subscrib-
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`ers.
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`CATV system 10 is a one-way delivery system based on
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`passband transmission. In the United States, each passband
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`consists of a downstream 6 MHZ channel, typically between
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`50 and 450 MHZ. The 5 MHZ through 42 MHZ spectrum is
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`reserved for upstream traffic. Many systems do not utiliZe
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`the upstream frequencies.
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`In recent years, fiber-optic cable has been deployed very
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`aggressively to replace traditional trunks between headends
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`and neighborhood nodes. Optoelectronic conversion equip-
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`ment is provided at the neighborhood node to make use of
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`the coaxial cable plant extending to the individual homes.
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`Fiber cabling increases reliability, reduces noise problems,
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`and decreases maintenance costs. This type of distribution
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`system is referred to as having a “hybrid fiber/coax” (HFC)
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`architecture.
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`In conjunction with the conversion to fiber trunks, the
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`number of homes supported by each neighborhood node has
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`dropped to between 500 and 2000 homes. This is much
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`smaller than the number of homes supported as little as 10
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`years ago.
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`Public HFC networks are being deployed not only by
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`CATV companies, but also by telephone companies. The
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`HFC networks deployed by telephone companies and some
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`CATV operators are switched systems designed to support
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`both broadcast video and switched broadband digital com-
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`munication services. Switched systems such as this typically
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`support much fewer homes per neighborhood node than
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`traditional systems. They also provide additional down-
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`stream channels for interactive services. Such additional
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`channels are typically in the 450 MHZ to 750 MHZ range,
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`and could extend up to 1 GHZ in the future. While analog
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`15
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`20
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`25
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`30
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`35
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`40
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`45
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`50
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`55
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`60
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`65
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`2
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`broadcast channels will initially occupy the spectrum from
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`50 MHZ to 450 MHZ, reallocations will probably be made as
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`interactive channels and services become available.
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`Newer, switched systems provide two-way communica-
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`tions using a back-channel which typically operates in the
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`range of 5 MHZ to 42 MHZ. In addition, switched systems
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`are capable of providing independent information services to
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`individual subscribers. For instance, each home can choose
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`its own information stream, such as a selected video or
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`motion picture, independent of other homes and independent
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`of broadcast schedules.
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`Some switched public networks use asynchronous trans-
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`fer mode (ATM) cell transmission. This technology uses
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`data cells with a fixed length of 53 bytes to reduce network
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`latency and allow better statistical multiplexing of informa-
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`tion on a given medium than available when using larger
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`packets of variable length. The fixed length of the cells also
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`simplifies switching them into and out of data media oper-
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`ating at different data rates.
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`FIG. 2 shows an ATM cell 21. The cell contains a 5-byte
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`header 22 and a 48-byte information field or payload 24. For
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`switching or routing purposes, only the header is significant.
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`The first four bits of the first byte of the header contain a
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`generic flow control field, designated GFC, which is cur-
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`rently not defined. It is intended to control the flow of traffic
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`in a shared media network. The next 24 bits (the last half of
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`byte one, bytes two and three, and the first half of byte four)
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`make up the ATM virtual channel number, also referred to
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`herein as a numeric routing indicator or a VPI/VCI value.
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`The numeric routing indicator is made up two subfields: a
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`virtual path identifier VPI and a virtual channel identifier
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`VCI. The VPI is formed by the first byte of the numeric
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`routing indicator. The VCI is formed by the second and third
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`bytes. The next three bits, designated PT for payload type,
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`indicate the type of information carried by the cell. The last
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`bit of the header’s byte four, CLP, indicates the cell loss
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`priority as set by a user or by the network. This bit indicates
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`the eligibility of the cell for discard by the network under
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`congested conditions. The last byte of the header, HEC, is
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`the header error control field. This is an error-correcting
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`code calculated across the previous four bytes of the header.
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`The HEC does not provide error checking or correction for
`
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`the payload. If such checking or correction is desired, it must
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`be performed at a higher protocol layer.
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`ATM networking depends on the establishment of virtual
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`connections. An ATM virtual connection is a series of links
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`between physical devices in a network. ATM uses virtual
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`channels (VCs) and virtual paths (VPs) for routing cells
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`through such physical devices. A virtual channel is a con-
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`nection between two communicating ATM entities. It may
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`consist of a concatenation of several ATM links. All com-
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`munications between two end points proceed along a one or
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`more virtual channels. Each virtual channel preserves cell
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`sequence and is guaranteed to provide a specified data rate.
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`A virtual path is a group of virtual channels. Virtual paths
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`provide a convenient way of bundling traffic all heading in
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`the same destination. Certain types of switching equipment
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`(referred to as VP cross-connect switches) only need to
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`check the VPI portion of a cell header to route the cell rather
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`than the entire three-byte address. For instance, a single VPI
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`might be used to indicate a path between two related offices.
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`The VCIs would be used only within the offices to determine
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`destinations within the offices.
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`In traveling from one end-point to another, a cell usually
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`passes through one or more ATM node switches. A switch
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`has a plurality of physical communication ports for com-
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`Netflix, Inc. Exhibit 1024
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`Netflix, Inc. Exhibit 1024
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`

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`6,084,876
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`4
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`BRIEF DESCRIPTION OF THE DRAWINGS
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`3
`munication with other switches or with individual end point
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`devices. Each port, however, is connected to only a single
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`ATM device. When a switch receives a cell, it routes the cell
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`to the appropriate port simply by checking its VPI/VCI
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`value, which has meaning only to the switch itself. By
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`looking at
`the VPI and VCI of a cell,
`the switch can
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`determine to which port the cell should be routed. Before
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`actually sending the cell, the switch replaces the VPI/VCI
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`value of the cell with that which will be needed at the next
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`switch.
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`In order for this switching to occur, a virtual connection
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`must have already been established through all of the
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`involved switches. This occurs using “call setup” messages.
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`To set up a virtual connection, an originating end point
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`device exchanges “signaling” messages with a destination
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`end point device and with the intervening switches. These
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`messages contain detailed information about the end point
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`devices and the intervening switches, including their ATM
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`20
`addresses. All devices along the desired path store this
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`information and associate it with a specific virtual
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`connection, specified within each device by a particular
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`VPI/VCI combination. Subsequent data communications
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`can then take place without any further specification of the
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`detailed addressing information, with only the VPIs and
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`VCIs.
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`FIG. 1 is a schematic diagram of a traditional broadcast
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`CATV system.
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`FIG. 2 is a diagram of an ATM cell.
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`FIG. 3 is a block diagram of an HFC switched broadband
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`interactive video entertainment network in accordance with
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`a preferred embodiment of the invention.
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`FIG. 4 is a block diagram of an STB in accordance with
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`a preferred embodiment of the invention.
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`FIG. 5 is a flow diagram of the general steps performed
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`in the preferred embodiment of the invention for transferring
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`ATM data cells.
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`FIG. 6 is a flow diagram showing preferred autoregistra-
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`tion steps in accordance with the invention.
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`DETAILED DESCRIPTION OF THE
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`PREFERRED EMBODIMENT
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`FIG. 3 shows an interactive video entertainment network
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`or system 30 having a switched broadband HFC architecture
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`in accordance with a preferred embodiment of the invention.
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`System 30 uses an ATM protocol as discussed above, in
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`which ATM data cells are transferred between end point
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`devices over virtual connections identified by VPI/VCI
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`values. System 30 includes a cable headend 32, at least one
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`and preferably a plurality of neighborhood nodes 34 (only
`one is shown), and a coax distribution plant 36. In the
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`preferred embodiment, bi-directional communication
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`between the headend and the neighborhood node is through
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`a fiber-optic trunk 38 between headend 32 and neighborhood
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`node 34. Neighborhood node 34 includes forward and
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`reverse optoelectronic conversion circuits 40 and 42 for
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`converting between the optical signal carried on fiber-optic
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`trunk 38 and the electronic signal carried by coax distribu-
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`tion plant 36. The fiber-optic trunk the neighborhood node
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`and the coax plant form an analog transmission medium that
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`connects to and serves a plurality of subscriber interface
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`units or set-top boxes (STBs) 44. The STBs are configured
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`as ATM end point devices in individual homes. More
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`specifically, the fiber-optic trunk and coax distribution plant
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`provide a plurality of upstream and downstream passband
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`communications channels between the headend and the
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`individual STBs. However, there is not a dedicated channel
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`for each STB. Rather, STB’s share upstream and down-
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`stream data channels using the apparatus and methods
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`described below.
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`Each STB has programmable components for communi-
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`cating with headend 32 using the ATM protocol and higher
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`level protocols such as internet protocol (IP). An individual
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`STB also has modulators and demodulators as appropriate to
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`tune to designated upchannels and downchannels. For
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`instance, an STB has one demodulator which is permanently
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`tuned to a control downchannel. Another demodulator is
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`settable or tunable to a selected data downchannel. Amodu-
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`lator is settable or tunable to a selected data upchannel. An
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`STB might also have a traditional tuner for receiving analog
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`broadcast signals from headend 32.
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`FIG. 4 shows the general configuration of a preferred STB
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`44 in accordance with this invention. Preferred STB 44
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`comprises first and second RF data receivers and demodu-
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`lators 130 and 132. First RF data receiver and demodulator
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`130 is permanently tuned to a fixed frequency or passband
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`communications channel
`to receive downstream control
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`information. Second RF receiver and demodulator 132 has
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`a variable tuner so that it can be tuned to any one of a
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`plurality of downstream frequencies or passband communi-
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`Netflix, Inc. Exhibit 1024
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`The description given above is merely an overview.
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`Further, more detailed information can be found in Asyn-
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`chronous Transfer Mode: Bandwidth for the Future, by Jim
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`Lane (Telco Systems, 1992); and in Asynchronous Transfer
`Mode: Solution for Broadband ISDN, 2d ed., by Martin de
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`Prycker (Ellis Norwood, 1993). Both of these references are
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`incorporated by reference.
`The physical network architecture shown in FIG. 1 cre-
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`ates some practical difficulties in implementing an ATM
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`protocol. One such difficulty is that a typical ATM architec-
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`ture requires a switch port for every physical end point
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`device. This can be expensive in a public system in which
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`every home in a very large metropolitan area might have an
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`end point device. Another potential difficulty arises from the
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`fact that upstream and downstream communications in the
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`system of FIG. 1 take place over different channels. Atypical
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`ATM architecture, however, expects that a node switch will
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`be able to conduct both upstream and downstream commu-
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`nications with a device over the same switch port. These
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`difficulties are solved by the architecture and methodical
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`steps presented below.
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`SUMMARY OF THE INVENTION
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`The invention described below provides an architecture
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`which allows the ATM protocol to be used in a public hybrid
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`fiber/coax network, without requiring a dedicated ATM
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`55
`switch port for every home. In the preferred embodiment, a
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`resource manager at the headend assigns each STB to a
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`specific combination of upstream and downstream commu-
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`nications channels. Multiple STBs are potentially assigned
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`to the same ATM switch port. Prior to data transfer, however,
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`an extended autoregistration procedure assigns an exclusive
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`range of VPI/VCI values to each STB. When setting up
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`virtual connections with a particular STB, a routing indica-
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`tor is chosen within the range assigned to the STB. During
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`data transfer, data cells originating from or destined to the
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`particular STB can be identified by their routing indicators.
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`This allows the same switch port to be used for a plurality
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`of STBs.
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`65
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`Netflix, Inc. Exhibit 1024
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`

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`6,084,876
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`5
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`cations channels for downstream data communications from
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`the headend to the STB.
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`STB 44 also has an RF modulator and data transmitter
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`134. Transmitter 134 has a variable tuner so that it can be
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`tuned to any one of a plurality of upstream frequencies or
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`communications channels for upstream ATM data commu-
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`nications from the STB to the headend.
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`STB 44 furthermore has a communications controller 136
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`that interacts with the data receivers and data transmitter. In
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`the preferred embodiment, communications controller 136 is
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`a general purpose programmable computer or microproces-
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`sor connected to receive demodulated data from data receiv-
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`ers and demodulators 130 and 132,
`to send ATM data
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`through RF modulator and data transmitter 134, and to tune
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`second RF data receiver and demodulator 132 and RF
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`modulator and data transmitter 134 to desired frequencies or
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`communications channels. The microprocessor also per-
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`forms other tasks within STB 44 such as executing various
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`application programs.
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`STB 44 has further components for performing other
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`tasks not directly related to this invention, such as a video
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`driver 138 for displaying graphic images on an associated
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`TV set. While the most common use for an STB such as
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`described above is in conjunction with televisions, an STB
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`in accordance with the invention will also enable subscribers
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`to access interactive online services,
`including services
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`which allow a subscriber to select from a large number of
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`movies and to schedule a selected movie to play at any
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`desired time. Other services might include financial services
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`or retail services. For instance, a subscriber might be able to
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`transfer funds between bank accounts or to order pizza
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`delivery through interactive services available on the
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`switched broadband network. Furthermore, STBs might be
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`used to allow other devices in the home, such as telephones
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`or home computers, to connect to the switched network.
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`The plurality of upstream and downstream passband
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`communications channels between the headend and the
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`STBs are frequency-division multiplexed over the fiber-
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`optic trunk. The channels are preferably 6 MHZ portions of
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`a frequency spectrum ranging from 5 MHZ to 750 MHZ.
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`These same channels are converted and duplicated on coax
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`distribution plant 36 to provide communications between
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`STBs 44 and neighborhood node 34. The channels carried
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`by fiber trunk 38 and coax distribution plant 36 include
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`downchannels and upchannels. Multiple 6 MHZ downchan-
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`nels are provided in the 50 MHZ through 750 MHZ spec-
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`trum. One of the downchannels is designated as a control
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`downchannel, while the remaining downchannels are data
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`downchannels. First RF data receiver and demodulator 130
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`of the subscriber interface unit described above is tuned to
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`the control downchannel. The single control downchannel is
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`shared by all STBs served by the neighborhood node and is
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`also used as a default downchannel for initial communica-
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`tions between the headend and an STB.
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`The upchannels occupy the 5 MHZ to 42 MHZ spectrum
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`(or a subset of that spectrum), preferably using a passband
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`scheme similar to that of the downchannels. One of the
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`upchannels is designated as a default upchannel, to be used
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`by all STBs when they are initially connected or turned on.
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`RF modulator and data transmitter 134 is initially tuned to
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`this upchannel for communications prior to the assignment
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`of communications channels as described below. The other
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`upchannels will be referred to herein as data upchannels.
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`Each upchannel is subdivided into logical upchannels for
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`use by a plurality of STBs by using a medium access (MAC)
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`communications protocol. Because the system might be
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`used for real-time applications, the MAC protocol used for
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`the data upchannels should be a reservation-based or time-
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`division protocol rather than a random access protocol. A
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`random access protocol might be suitable for the default
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`upchannel or for upchannels which are designated strictly
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`for upstream control data.
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`Rather
`than using a passband scheme for
`logical
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`upchannels, it might be desirable in some situations to utiliZe
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`spread-spectrum techniques such as code division multiple
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`access (CDMA) techniques in which the STBs would all
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`share the entire 5 MHZ to 42 MHZ spectrum (or a subset).
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`Referring again to FIG. 3, headend 32 includes shared
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`components 46 and dedicated components 48. The shared
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`components are used by all neighborhood nodes and STBs
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`served by headend 32. The dedicated components are rep-
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`licated for each neighborhood node 34.
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`Shared components 46 include an ATM distribution net-
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`work 50 and one or more headend servers 52. The ATM
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`distribution network contains any required ATM switches
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`for establishing whatever connections might be required to
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`support individual STBs. The system includes connections
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`54 to external networks so that subscribers can access
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`services provided by outside vendors. ATM distribution
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`network 50 also includes connections to servers 52. Servers
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`52 contain libraries of video or other information streams
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`which can be selected by subscribers for viewing or other-
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`wise accessing on demand.
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`Dedicated components 48 include an ATM node or node
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`switch 56 associated with headend 32, having multiple
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`downstream switch ports 58 and at least a single upstream or
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`bi-directional switch port 60. The downstream switch ports
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`are individually connected to send communications to the
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`STBs through respective individual downstream communi-
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`cations channels. In general, there is a downstream switch
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`port 58 corresponding to each 6 MHZ downchannel. The
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`single upstream or bi-directional switch port 60 is config-
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`ured to receive communications from the plurality of STBs
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`through the plurality of upstream communications channels.
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`As discussed above, each STB is configured to tune to any
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`one of a plurality of the downstream communications chan-
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`nels and therefore to connect to any one of a plurality of the
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`switch ports for communicating with the ATM node switch.
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`Adata transmitter and modulator 62 is connected between
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`each downstream switch port and the fiber-optic trunk to
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`transmit modulated data on a selected passband channel
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`from the ATM node switch, to the neighborhood node, and
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`then through the coax plant to individual STBs. A separate,
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`analog feed 64 is provided for conventional broadcast video.
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`A control channel
`transmitter or modulator 68 is also
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`included in the dedicated components. Control channel
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`transmitter 68 modulates the single control downchannel to
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`the STBs associated with a particular network node. The
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`outgoing signals are combined in a mixer 65 and converted
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`to optical format by a modulating laser device 67.
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`The dedicated components also include facilities for
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`receiving data on the upstream communications channels.
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`Separate receivers and demodulators 66 are provided for
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`receiving modulated signals from STBs on each of the
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`upchannels and for converting these signals to digital for-
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`mat. An optical-to-electronic converter 69 is used to provide
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`an electronic signal to the demodulators from the fiber-optic
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`trunk 38.
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`Dedicated components 48 furthermore include an
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`upstream controller 72 and a resource manager 74. Upstream
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`controller 72 is responsible for multiplexing upstream data
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`from the multiple logical and physical upchannels onto
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`Netflix, Inc. Exhibit 1024
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`Netflix, Inc. Exhibit 1024
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`6,084,876
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`10
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`15
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`7
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`single switch port 60 of ATM node switch 56 and for
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`managing the MAC protocol used by the upstream channels.
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`Resource manager 74 is responsible for allocating both
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`upstream and downstream channels to individual STBs as
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`will be more fully explained below. These components,
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`along with demodulators 66 and control channel transmitter
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`68, are preferably integrated on a single microprocesso