TECHNICAL PAPERS ”
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`ARRIS883IPRI0000828
`
`

`

`1982 CONVENTION TECHNICAL PROGRAM SUBCOMMITTEE
`
`Wendell H. Bailey, Chairman
`National Cable Television Association
`
`Norman P. Weinhouse
`Hughes Communications
`
`Scott Tipton
`Home Box Office
`Tom Polis
`
`Communications Engineering Management Services
`
`Joseph Van Loan
`Viacom Cablevision
`
`Charles Eissler
`
`Oak Communications, Inc.
`Alex Best
`
`Scientific-A tlanta, Inc.
`
`NCTA SCIENCE & TECHNOLOGY DEPARTMENT
`
`Wendell H. Bailey
`Vice President
`
`Katherine S. Rutkowski, Assistant Director
`Technical Program Coordinator
`Barbara J. Avent
`Administrative Assistant
`
`Additional copies are available from NCTA,
`Science 8 Technology Dept.
`1724 Massachusetts Ave., NW, Washington, D.C. 20036
`(202) 775-3637
`
`Copyright© 1982, The National Cable Television Association,
`1724 Massachusetts Ave., NW, Washington, D.C. 20036
`
`IS BN 0-940272—05-9
`
`ARR|8883|PR|0000829
`
`ARRIS883IPRI0000829
`
`

`

`This material may be protected by Copyright law (Title 17 US. Code)
`
`MetroNet:
`
`An Overview of a CATV Reqibnal Data Network
`
`R. P. McNamara
`Sytek,
`Incorporated
`
`P.E. Morse
`Jerrold Division, General Instruments
`
`the Public Switched Tali“
`to
`alternative
`Phone Network (PfiN). This market
`is beins
`driven
`bv
`the attempts oF mant companies
`to imrrove white
`collar worker
`produc~
`tivitv bY deplovins "DFFice of the Future"
`enhancements.
`The second market
`segment
`is
`that
`of
`the
`residential
`consumer.
`Unlike the business market,
`the
`residenw
`tial
`consumer market
`does not vet exist
`and will have to be developed.
`'
`The telecommunication services which
`being developed For
`the home consumer
`are
`environment are usuallv consolidated under
`the
`umbrella
`of Videotezx. Services.
`It
`would appear saFe to assume that
`the
`cost
`0F
`providins network access and transport
`will have a strons bearing on the ultimate
`penetration of Videotem services in the
`residential market.
`This
`Paper
`will
`describe
`a
`network
`which
`directlt
`addresses the
`needs
`oF
`the
`residential
`marketplace and will Focus on describing a
`general
`architectural
`overview
`of
`MetroNet. a CATV regional data network.
`
`the
`is projected that
`It
`market will provide combinations of audio.
`textual and graphical
`information
`to
`the
`home
`subscriber.
`T9 manvv experts:
`the
`emergence 0F thts market durins t“? decade
`0;
`the
`80a?
`19
`a .certaintv.
`The ““17
`question 'which
`remains
`is whether
`the
`maPEEt
`”111
`EVD1VE
`as
`an QKtengifi“ QF
`P1a1”
`0‘?
`tQTQPhone
`SQTV1CG
`(POTi)
`9"
`whether
`1*
`”11] be PrfiwldEd by a” a1tEFT
`nate local di5tpibUti0“ SYStem'
`the cable.
`[13
`It is our contention that the nature
`OF the service (data):
`the traFFlc Chapéc"
`teristics oF the serv1ce (burstv transmis—
`sion and lons holding timeslw the ttpe
`oF
`Plant
`the service is FPDVided 0" (CiFCUit
`switched. analos) and the recent movement
`.
`of
`local
`telephone companies to cost based
`pricing
`(designated Universal
`'Measured
`5?PV1CE)
`”1‘!
`make
`the
`PPOVlSlD”
`0*
`VideotEfi
`services
`?Ver
`the
`currentlv
`déPI°YEd
`PUb11C 5m}tChed Network (PfiN) a
`costlv and unattractive _°FF@P}“5-
`“5
`a
`cost
`eFFective alternative: Videotem Ser—
`vice could be provided by local CATV Fran~
`chises.
`
`éhstnact
`
`performance
`hish
`is a low cost,
`MetroNet
`data communications network which is based
`on a svnersistic combination of
`broadband
`analosy disital and packet switching com"
`munication technolosies. MetroNet
`is seen
`as
`a means oF Providing a cost eFtectivea
`data
`communications
`link
`to
`the
`small
`business
`and
`residential consumer market
`over currentlv deploved cable ststems.
`
`and
`the marketing:
`Adescriptinn (Hi
`For
`requirements
`network
`communication
`MetroNet. along with general architectural
`considerations
`»
`both
`hardware
`and
`software, are discussed.
`
`1'
`
`-
`..
`Introduction
`The evolution of new services oFFered
`cable operators is beins driven bv the
`by
`demands of users and Franchise authorities
`For
`additional
`value
`added services and
`the need oF MSUS to Senorate
`new revenue
`streams.
`An area oF active investisation
`or mant MSUs
`is the PPflViSiflnifiS of a
`two
`war data communication link over
`the cable
`network. This data link is
`the
`backbone
`over which manv of
`the contemplated ser"
`Vice“ ”11] be Provided.
`a
`
`to
`appear
`Two market segments would
`_" '"'_ rt re d (ir terns CF traFFi:
`'
`have nlfinlflra'
`I e
`|
`h I
`I
`volume) For a
`data
`communications
`back-
`bone:
`the business market and the residen"
`tial consumer market.
`The business market
`
`havins a substantial d.
`.
`contains
`users
`communication need and who would welc~ne
`the
`capacitta
`tflPOlflSV and
`cost savind
`potential
`me
`a
`EATV
`network
`as
`an
`
`ARR|S883|PR|0000830
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`
`
`
`
`
`
`consumer
`
`ARRIS883IPRI0000830
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`

`

`Perfor—
`is a low cost. hish
`MetroNet
`mance. data communication network and is a
`svnersistic combination ot broadband
`ana-
`los. disital and Packet switchins techno-
`losies. Utilizins
`standard
`cable
`TV
`facilities. MetroNet will Provide a tran—
`sParent. hish Performance.
`communication
`svstem incorPoratins distributed network
`intellisence.
`For
`the residential
`consu—
`mer market. MetroNet will be comPatihle
`with all existins (subsPlit and midselit)
`cable svstems. Unlike other ProPosed CATV
`data networks. MetroNet makes
`no
`assumP—
`tion as
`to where in the network control
`and service nodes are located.
`As
`such.
`MetroNet
`is
`comPletelv Seneratized as to
`service
`node
`dePloYment.
`The MetroNet
`svstem architecture will
`Provide
`the
`interconnection of a wide
`ranse
`oF
`sub—
`scriber
`and
`service nodes. configuration
`Flexibilitv. and the abilitv For
`a
`low
`cost Phased introduction oF service.
`
`One of the underlvins desiSn soals of
`MetroNet
`is
`that it must Provide todav’s
`Videotex services inexPensivelv vet
`still
`have
`the Flexibilitv required For Future
`network srowth and aPPlications.
`The sen—
`eralitv at
`the svstem enables it to eFFec-
`tivelv service a wide ranse of user aPPli-
`cations
`- from control and securitv moni—
`torins svstems to Packetized LPC voice and
`data.
`
`an
`This PaPer will Provide
`the MetroNet Svstem.
`Amons
`oF
`discussed will be:
`
`overview
`the areas
`
`t Residential Market Requirements
`
`o Network Requirements
`
`o MetroNet’s Network Architecture
`
`2. Besideniial_Macket_Besuicements
`
`This section basins bv addressins the
`home telecommunication market and extraPo—
`latins the consumer
`network
`requirements
`bv
`examinins
`the ranse and tvres of ser—
`vice which will
`he
`dePloved.
`The
`
`to studt all P055i“
`intention here was not
`ble Future services in sreat detail.
`but
`rather
`to Forecast eeneral
`trends in the
`development of this market and to estimate
`their
`imPact
`on
`the
`telecommunications
`network that will
`tranSPort
`these
`ser—
`vices.
`These ProJections were
`used to
`create
`network
`traffic model
`in
`an
`effort
`evaluate
`the
`network PéPFOP”
`mance.
`
`a
`to
`
`the
`For
`Forecasting service demands
`residential marketPlace is not a straisht~
`Forward undertakins.
`Indeed. manv studies
`conducted
`durins
`the
`last
`decade
`have
`
`this
`oF
`develoPment
`Predicted raPid
`Generallw.
`these Forecasts
`market.
`[2]
`came as a result of
`anticiPation of
`the
`results of
`the intesration of new comPuter
`technolosv and advances in both
`telePhone
`and
`cable
`television communication ser*
`vice.
`It was eXPected that this
`intesra-
`tion would make Possible and.
`indeed. sub"
`stantiallv lower
`the
`cost
`of
`a
`wide
`varietv of
`services that Previouslv were
`not handled electronicallt.
`
`have
`chanses
`in man? cases
`However.
`than eXPected. ExcePt For a
`slower
`been
`broader varietv of television Prosrammins.
`increased
`use
`oF
`video
`games. and some
`custom callins Features.
`the home telecom—
`munications market
`is not aPPreciablv diF-
`Ferent From that oF ten Years ado.
`
`For
`oFFered
`be
`could
`Manv reasons
`Primarv amons
`this belated develoPment.
`these is the requirement
`that manv
`actors
`in
`the marketplace
`have
`to
`undertake
`activities
`simultaneoule.
`Generallv.
`there
`is
`not one drivins force but mant.
`The offering oF a service
`such
`as
`elecv
`tronic Funds transfer necessities sidniFi—
`cant resource allocation on
`the Part
`of
`banks.
`communication
`comPanies.
`informa~
`tion Processins Firms.
`and
`residents.
`Market
`sisnals
`have
`to
`be
`VEPY
`clear
`before this investment will
`be Forthcom-
`ins.
`Individuals
`or Firms that maY lose
`market
`share
`should
`conditions
`chanse.
`e.s.
`sellers
`of PaPer. mat delav throush
`lesislative or Judicial means.
`Finallv.
`resulatorv uncertaintv has also resulted
`
`in reluctance on the Part of market Partie
`ciPants to make the required investments.
`
`tend
`ManY oF the Forces which would
`eXPand
`the
`home
`telecommunications
`to
`market still exist
`today
`.
`but
`counter
`Forces are also Present. Thus. one of the
`fundamental desisn criteria For MetroNet
`was
`that
`the network architecture had to
`be modular and allow For either
`raPid
`or
`slow develoPment
`oF the consumer market—
`Place.
`
`these new ser—
`range of
`The Potential
`vices
`such diverse
`areas as'
`encomPess
`ener3v management. home security. bank and
`shoP at
`home.
`video
`games.
`electronic
`directories and Personal data storase.
`to
`name
`a
`Few. While the ProJected market
`For these services is eXPected to he
`sis—
`niFicant.
`the most ditficult issue at this
`time is identiFYins those
`services which
`Form the
`base or “critical mass" For
`the
`develoPment of this marketPlace.
`Unlike
`the Business Marketplace. which is beins
`driven bY a need For greater Productivitv
`in the oFFice market.
`the residential con~
`sumer
`is motivated by a difFerent
`set
`of
`needs. Most consumers accePtance oF a new
`service ( or
`set
`oF
`services) will
`be
`
`23
`
`ARR|S883|PR|0000831
`
`ARRIS883IPRI0000831
`
`

`

`on the savinss or perceived savinss
`based
`that the service offers to the subscriber.
`Table I summarizes the kev services.
`their
`traffic characteristics. and their market
`Penetration bv 1990.
`The peak traffic was
`developed from a model of each Prospective
`service.
`It
`should
`be
`emphasized that
`these services were used as an
`indication
`of
`the
`core or critical mass of services
`and formed
`a baseline
`for
`the
`network
`traffic model.
`
`Penetration
`Peak Traffic
`I
`I
`I
`I
`I
`I
`(Total)
`Bits/Sec/
`I
`SERVICE
`I
`I
`I Households
`Residence
`I
`I
`I ———————————————— I —————————————————— I ————————————— I
`I1) Home Bankins I
`2.6
`I
`307.
`I
`I2) Home Shopping:
`11.35
`I
`251
`I
`I —Comparison
`I
`I
`I
`I
`Shoppins
`I
`7.1
`I
`507.
`I
`I
`~Reservations I
`I
`I
`.12
`207.
`I3) Electronic
`I
`I
`I
`I
`Mail
`I
`2.66
`I
`27.
`I
`I4) Electronic
`I
`I
`I
`I
`Newspaper
`I
`I
`I
`I
`— News
`I
`I
`I
`I
`— Public
`I
`I
`I
`I
`Notices
`I
`I
`I
`I
`- Classified I
`I
`I
`I
`— Financial
`I
`I
`I
`I5)
`Information
`I
`I
`I
`I
`Services
`I
`I
`I
`I
`— References I
`I
`I
`I
`— Traffic
`I
`I
`I
`I
`Conditions:
`I
`I
`I
`- Software
`I
`I
`I
`I
`Packases
`I
`I
`I
`I6) SecuritY
`I
`I
`I
`I
`Services
`I
`I
`I
`I7) Enersv
`|
`I
`I
`I
`Management
`I
`I
`I
`I6) Education
`I
`I
`I
`I
`Prosr-am
`I
`I
`I
`I9) Medical
`I
`I
`I
`I
`Monitorins
`I
`I
`I
`I10)EntertainmentI
`I
`I
`|
`Services
`I
`I
`I
`I
`— Video GamesI
`I
`I
`I
`— Gamins
`I
`I
`I
`
`207.
`307.
`307.
`107.
`
`307.
`207.
`107.
`57.
`107.
`57.
`17.
`
`307.
`157.
`
`15.5
`.16
`1.6
`1.75
`
`15.5
`6.5
`.77
`.3
`.14
`37.
`.3
`
`1.68
`.20
`
`3. Netwo:k-Resuicements
`
`intesrated
`the
`MetroNet will act as
`data communications backbone for all value
`added services to
`the
`home.
`This
`role
`places
`some rather unisue requirements on
`the network implementation. MetroNet must
`support a wide ranse of applications. manv
`of which
`have
`not
`been
`identified (in
`Table
`I
`above)
`or
`developed.
`In
`the
`
`realized that
`design of MetroNet. it was
`the network should provide a wide ranSe of
`performance. customized to
`the
`needs
`of
`each
`application.
`Nideband.
`low delav
`applications
`should
`coexist with
`narw
`rowband.
`delav
`tolerant
`applications
`without requirins the latter
`to
`pat
`the
`cost
`of the former. Furthermore. as more
`data traffic. users and
`applications
`are
`misrated
`to an intesrated.
`resional data
`communications
`network.
`an
`increasins
`number
`of
`them will require privacv and
`securitv features to safeguard their
`data
`From other users. These Features should
`
`24
`
`ARR|8883|PR|0000832
`
`not
`users
`that
`be modularlv included so
`do not pav for
`requiring these
`services
`them and. further.
`that the full
`intercon—
`nectivitv of
`the network is not comprom—
`ised. Stated another mat. a
`secure
`user
`should
`be
`able
`to Optionallv invoke the
`securitv and privacv services of
`the
`net“
`work.
`
`desisn
`network
`the
`of
`summarv
`A
`requirements is shown in
`assumptions
`and
`Table II.
`These assumptions and
`require—
`ments were
`used
`to
`define the MetroNet
`svstem architecture and
`discuss
`such
`issues
`as Network
`topolosv.
`bandwidth.
`connectivitv and control.
`
`architecture
`The choice of a network
`was most stronslv affected bv the follow—
`ins network requirements:
`
`0 The
`burstv.
`
`have
`network would
`data tvpe traffic.
`
`to
`
`support
`
`assumed
`a Network bandwidth is
`scarce and valuable resource.
`
`to
`
`be
`
`a
`
`e The network will be deploted in
`tile environment.
`
`a
`
`hos—
`
`The first two requirements
`be
`could
`in desisn to
`bv
`a
`network
`similar
`met
`product
`line.
`SYTEi’s Svstem 20 LocalNet
`a distributed intelligence.
`that
`is.
`packet
`switched
`network.
`However.
`the
`third requirement mandated that some form
`
`of centralized network administrative con—
`trol be provided to Prevent fraud (both of
`the network and of other users).
`
`the MetroNet
`of
`In the development
`architecture.
`it became apparent that con—
`sideration must be siven
`as
`to
`how the
`services depicted in Table I are provided.
`Specific issues considered with respect
`to
`service provisionine.
`included: who pro~
`vides the service.
`the
`location of
`the
`service node.
`the size of
`the service node
`~ amons others.
`
`cen—
`between
`A comparison was made
`node
`tralized vs decentralized service
`node
`‘deplovment.
`A
`centralized service
`(or
`was
`characterized as beins located at
`In
`trunked to) the cable svstem headend.
`this
`scenario.
`all services are provided
`bv
`the M30.
`A decentralized
`network
`architecture would allow service nodes to
`be phvsicallv located anvwhere in the net-
`work. Services mat-or maY not be provided
`bv the M30 — that is. manY service
`nodes
`would
`be
`provided
`bv outside vendors or
`entrepenuers.
`The non— MSO service
`nodes
`would still senerate a revenue stream for
`
`
`
`
`
`
`
`
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`TABLE II
`
`Network Requirements
`
`Assumetinns
`
`desisned
`be
`0 Market — The network will
`to
`suPort
`the small business/ residential
`market
`
`— The network will be designed
`t Traffic
`to sureort disital data ttre traffic
`
`imrle-
`— The network will be
`o Torolosv
`mented over a broadband CATV network which
`exhibits a "tree" tvre rhvsical
`torolosv
`
`is
`bandwidth
`Network
`—
`o Bandwidth
`and valuable
`a
`scarce
`be
`assumed
`to
`the
`network
`resource.
`It is assumed that
`will
`be
`implemented
`in a subsPlit cable
`svstem with a maximum of 25 MHz
`(one wat)
`allocated For data services
`
`be
`network will
`The
`~
`o Environment
`a hostile environment and be
`derloYed
`in
`subJected to both accidental and
`premedi~
`tated attacks.
`
`architecture
`network
`— The
`o Standards
`will not necessarilv conForm with IEEE (or
`other standard organizations deFined stan~
`dard
`network.
`The network. however. will
`conForm with the ISU seven level
`Protocol
`architecture and will
`Present
`standard
`interFaces to connecting
`nodes
`and
`net~
`works.
`
`Beoecal Resuicements
`
`- The network will
`o Geosrarhical Extent
`traFFic within a 20
`be
`able
`to
`support
`mile radius of
`the
`network
`head
`end
`or
`some
`other
`centralized network node col—
`lection Point.
`Provisions
`For
`expanded
`aeosrarhic
`coverage must
`be included in
`the basic architecture.
`
`Connectivitx
`
`allow
`The network will
`o Connectivitv —
`For
`the logical
`interconnection of anv two
`nodes.
`
`— Nodes. both subscriber
`4 Node Location
`and server. mav be thsicallv located anv—
`where in the network.
`
`network
`The
`-
`t Communication Services
`will Provide a full
`ranse oF communication
`services
`
`Subscriber
`—
`o Connection Throughput
`nodes will
`have a throughput 0F at
`least
`19.6 Kb/s
`
`network will
`The
`~
`a Internetworkins
`allow For
`the connection to and From oFF
`network nodes Provided the Proper
`inter—
`Faces and connections exist.
`
`Netwonk Conical
`
`network
`0 Access and Authorization — The
`will be able to identiFY. authenticate and
`the
`This
`an
`net—
`
`to
`node
`srant or dent access oF an?
`transport
`services
`of the network.
`implies that the network will
`Passes
`enforcement mechanism which can dent
`work access to unauthorized nodes.
`
`will be capable
`o Caracitv — The network
`base
`oF at
`of
`supporting a
`subscriber
`More
`complex
`subscribers.
`least 50.000
`interconnected net"
`svstems
`oF multiwlv
`works mat be dePloted.
`
`be able to
`o Securitv — The network will
`(both
`Protect
`itself
`asainst
`vandalism
`From
`Physical and electrical) theft
`(both
`and
`the
`network
`and
`authorized
`users)
`attacks against user data Privact
`
`cost
`be
`o Cost — The network will
`tive For
`the consumer marketplace.
`
`efFec—
`
`should
`network
`The
`—
`o Plannins Cvcle
`caracitv
`not
`exceed allocated RF srectrum
`after
`ini~
`For at
`least a 10 vear Period
`provisions
`For
`tial
`deplovment
`and
`expanded srowth must be
`included
`in
`the
`basic architecture.
`
`network
`The
`o Adartabilitv —
`and will
`Flexible
`extensible
`current and Future services
`
`be
`will
`support
`
`Under
`—
`o Access Time
`maximum loading
`network will accept and
`the
`conditions.
`transmit 99% 0F the Packets
`it
`receives
`within 100 milliseconds.
`
`Posses
`— The network will
`o Monitorins
`analos monitorins carabilitv
`digital
`and
`For maintenance.traFFic
`allocation.
`and
`accountins Purroses
`
`Beliahilitx
`
`be
`network will
`The
`—
`a Reliabilitv
`reliable such that the entire ststem down~
`time is less than three minutes Per month
`
`network
`The
`—
`t Network Control Nodes
`control nodes will be configured in such a
`Fashion so as to meet
`the
`network
`relia~
`bilitY requirements.
`
`25
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`ARR|8883|PR|0000833
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`

`oF traffic on the net—
`the M80 in the Form
`work,
`more services For
`the consumer, node
`access charsesa
`etc. Furthermore,
`the MSG
`billins
`support for these
`could
`provide
`service
`nodes
`so
`that
`the
`consumer
`receives
`Just
`one bill,
`not multiple
`bills, For Videotex Services.
`
`investisated
`Another area which was
`the
`issue of
`service node reliabil~
`was
`itv, complexitv and size.
`The
`last
`area
`to be considered was the resulatorv impact
`on a centralized vs decentralized servins
`arranSement.
`For
`resulatort
`reasons
`alone:
`it is ProJected that a
`centralized
`service
`node
`architecture will
`leave the
`M80 open to Ions term lesal
`entanslements
`and
`resulation.
`This reasoning is based
`on a Projection of "creepins"
`resulation.
`Noteworthv examples which come to mind are
`recent mandates requirins the CATV
`indus“
`tPT to
`provide two wav capabilitt (FCC),
`interconnection of
`franchises
`(various
`state
`PUCs).
`and some censorship of CATV
`offerinSS
`(various
`Franchises).
`This
`concern
`appears
`to be substantiated ht a
`of
`the
`recent M.I.T. report on resulation
`CATV Industrt [4].
`
`cen—
`at
`To Further pursue the issue
`node
`tralized vs decentralized service
`eFFort
`deplovment an examination
`or
`the
`and
`time
`needed
`to add new services and
`Features to a svstem was perrormed .A sum—
`mart
`of these Findings are shown in Table
`III and clearlv Favor decentralized serv—
`ins arrangements.
`
`network
`Based on the assumptions and
`and
`the
`requirements
`From
`Table
`II
`distri—
`requirement that service nodes he
`it
`is
`buted
`throushout
`the
`network,
`resional
`apparent
`that
`the needs
`of
`the
`area data
`network could be provided bv a
`distributed intellisencey packet
`switched
`network.
`However.
`it was decided that a
`centralized network control Function which
`allowed
`the network administrator to con“
`trol
`network
`access,
`subscriber
`node
`deplovmenta
`and distribute
`traffic was
`also necessart.
`The resultant hvbrid net—
`work
`is MetroNet.
`It
`is Felt
`that
`MetroNet Provides an
`optimum mixture
`of
`decentralized
`network
`intellisence and
`reliabilitt with
`centralized
`control.
`Additional Flexibilitv is Provided in that
`MetroNet will allow For
`the deplotment
`of
`either
`centralized or decentralized ser—
`vice nodes.
`
`TABLE III
`
`NETWORK ARCHITECTURE - CENTRALIZED VS
`DECENTRALIZED
`—SERVICE RELATED ISSUES—
`
`I ——————————————————————————————————————— I
`I
`I Central
`I Decentral
`I
`I ———————————————— I ---------- I ——————————— I
`IEFFort
`to add
`I
`I
`I
`Inew services
`I Harder
`I Easier
`I
`I
`I
`I
`I
`to
`IEFFort
`I
`I
`I
`Iincrease service!
`I
`I
`Icapabilitv
`I Harder
`I Easier
`I
`I
`I
`I
`I
`I
`I
`I
`l
`to
`IEfFort
`I
`I
`I
`Idevelop service I Harder
`I Easier
`I
`l
`l
`I
`I
`I
`I
`I
`I
`ITime to develop I
`I
`I
`Inew service
`I Lonser
`I Shorter
`I
`I
`I
`I
`I
`I
`I
`
`4. Metanet-encbiiectuce
`
`data
`switched
`packet
`is a
`MetroNet
`provides communication via
`network which
`the CATV distribution network.
`The
`net—
`work
`consists
`oF
`three Seneric tYpes of
`nodes ~
`network
`control
`and monitorins
`nodes,
`user
`nodes, and network interface
`nodes.
`The network architecture
`For
`For
`MetroNet
`is outlined in Fisure 1.
`A net"
`work consists of
`the followins elements:
`
`Cable Distribution 8vstems
`o Data Channel Access Monitor
`Network Control Nodes
`(NAG)
`0 Network Access Controller
`0 Network TraFFic Monitor
`(NTM)
`0 Network Resource ManaSer
`(NRM)
`
`(BEAM)
`
`User Nodes
`o Subscriber Node
`0 Server Node
`
`Network InterFace Nodes
`(optional)
`o
`Intranetwork Links
`o
`Internetwork Gatewavs
`(optional)
`
`the
`of
`consists
`network
`core
`The
`cable distribution svstem:
`the Data Chan”
`nel Access Monitor:
`the Network Access
`Gontroller.
`the Network Resource Manager,
`the Network Traffic Monitor, and two nodes
`which want
`to communicate with each other.
`
`A ttpical session in MetroNet is initiated
`when a subscriber node sisnals the Network
`Access Controller (NAC) and
`is
`allocated
`channal
`bandwidth.
`The
`subscriber
`then
`initiates
`a
`session with
`the
`Network
`Resource Manaser which authenticates the
`session request
`and
`assisns
`a
`specific
`network
`channel
`For
`the subsequent ses-~
`sion.
`
`26
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`two treauencv bands! an urstream (low Fre-
`auencv) and a downstream band
`(hish
`Frew
`auencv)
`and
`are
`compatible with either
`
`a
`In
`subsplit or midsrlit cable ststems.
`subsPlit CATV svstem the band From S to 30
`MHz
`is tVPicallv used
`For
`transmissions
`towards
`the cable head end.
`The outbound
`directorv will be contained in
`a
`25 MHz
`band
`somewhere
`in the 54~400 MHz resion.
`It should be Pointed out that
`the
`actual
`Frequencv allocations
`of
`the inbound and
`outbound
`bands
`are
`unimportant
`in
`the
`MetroNet architecture.
`
`The MetroNet architecture divides the
`urstream and
`downstream bandwidth
`into
`multirle logical channels throush the
`use
`of Freauenct Division MultiPleHins (FEM).
`Frequent? ShiFt Kevins (FSK)
`is
`used
`to
`modulate
`RF carriers to create individual
`data channels.
`Each MetroNet data channel
`will
`have a throushPut oF 123 Kb/s and is
`caPable of supPortins
`hundreds
`of
`users
`because oF both the CSMA/CD access mechan~
`ism and the Packet switched tormat.
`
`oF
`one
`As was Previouslv seeciFied.
`requirements
`of MetroNet will be to
`the
`Provide access to network tranSPort Facil-
`ities
`and
`user
`accountabilitt. Both 0F
`these requirements will be met
`throush the
`use
`oF
`a semi—intellisent head end — the
`Data Channel Access Monitor
`(BEAM)
`
`the CATV
`The BEAM at
`will PerForm two Functions:
`
`svstem headend
`
`receive
`a It will
`the UPstream channel
`transmission
`(data
`Packets) and rebroad~
`headend
`cast
`these transmissions from the
`to all
`a
`in
`sreciFied downstream channel
`attached user devices: and
`
`the Network
`o It will, under direction of
`Access Controller
`(NAB),
`examine
`everv
`data Packet Passing throush
`each
`headend
`channel.
`Packets
`From unauthorized net~
`work users will not be rebroadcast
`to
`the
`network.
`This
`stratesv will Prohibit
`unauthorized
`network
`access
`and
`mis—
`directed billinSs
`bt
`"sPooFins"
`oF the
`Network TraFFic Monitor.
`
`The network headend will be oraanized
`.
`on a Per channel basis.
`Each network data
`channel consists of a (low band) demodula—
`tor,
`a Packet verification unit, and a
`(hish band) modulator.
`Each
`droUP
`(~10)
`of
`DCAM modules ( one module Per channel)
`will have a "hot"
`stand
`bv
`in
`case
`oF
`Failure
`of
`the online unit. Reliabilitv
`is Provided through 1 For N redundancw in
`DCAM units.
`It should be noted that even
`if there were a Failure in
`both
`a Front
`line
`and
`back
`uP
`DCAM module.
`the
`remainder of the network would
`be
`una'F-~
`Fected
`and continue to oPerate.
`The net“
`work Protocol architecture will be conFis~
`
`Information flow in the network would
`from each
`node
`toward the head end.
`be
`headend
`receives
`each
`uPstream
`The
`transmission and
`rebroadcasts
`it
`on
`a
`sPeciFic downstream channel.
`The
`headend
`contains
`the
`enforcement mechanism which
`Prevents network
`access
`(that
`is
`—
`it
`prevents network Packet retransmission) oF
`unauthorized Packets. Authorized Packets
`are rebroadcast downstream toward the net~
`work nodes. All session transmissions are
`monitored
`b7
`the Network Traffic Monitor
`(NTM) which sathers network usase
`statis—
`tics
`For
`load management and accountins
`PurPoses.
`If MetroNet extends beyond
`the
`local
`aeoSraPhical
`area.
`the network can
`be connected throush either
`an
`Intranets
`work Link or an Internetwork Gatewat.
`The
`Function oF these comronents
`are
`summar~
`ized in the Following sections.
`
`mi: ,
`
`
`
`To Subscriber/Server
`Nodes
`
`
` i
`
`
`ET fl 'E
`
`Network
`Network
`Netwock
`Acces
`Resumes
`Txagfic
`Controller
`Haraqsr
`Mnmmr
`
`Gateway
`
`
`
`Subset the:
`Subscriber
`Terminals
`
`Terminals
`
`
`
`
`
` :5Subscribe:
`‘D
`Server Nudes
`Terminal:
`
`4.1 Cable-flistnibution_Netwnck
`
`Figure 1
`
`coaxial
`broadband
`MetroNet utilizes
`CATV
`cable
`as its PhTSiEal communication
`medium.
`Analos
`video
`applications
`can
`share
`the same cable as the MetroNet data
`network.
`Since broadband CATV is a direc~
`tional broadcast
`transmission svstem based
`on a sinsle.
`rooted tree: PhYSiCal
`tOPUl”
`osv, each network node can broadcast their
`transmission in one,direction1 ur the tree
`towards
`the
`CATV headeend.
`The headvend
`contains a
`FreauencY translation device
`(DEAN) which rebroadcasts the transmission
`From the root of
`the
`tree
`downstream to
`all attached nodes. MetroNet GKPIOitS the
`directional asPects of the CATV
`transmisw
`sion
`system to achieve Full connectivity.
`MetroNet
`transmissions
`are
`contained
`in
`
`27
`
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`ARRIS883IPRI0000835
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`

`

`if a UCAM module
`a mat that
`ured
`in
`such
`the user nodes would deFault
`were to Fail.
`to
`their
`home
`channel
`and
`the Network
`Resource Manaser would then reassign nodes
`to other
`data channels.
`The maJoritY oF
`users probable could recover and be
`reasr
`sisned to
`other
`data
`channels without
`detection of
`a
`network Fault.
`(It
`is
`anticipated
`that
`the
`onlv discernible
`eFFect
`to a user would be a short delav or
`dead
`time before the network would recon—
`Fisure and it is
`sussested that
`such
`a
`delaY might be diFFicult
`to discern From a
`server node slowdown).
`
`a
`on
`proceed
`Network srowth would
`channel
`bY
`channel basis. Cable svstems
`which require more data channels would
`be
`outtitted with more channels while smaller
`svstems could be sized appropriatelY.
`
`the
`that
`out
`pointed
`It should be
`network
`is orsanized so that nodes can be
`located anvwhere in the network.
`Network
`control
`nodes. subscriber nodes or server
`nodes mav be located PhYsicallv anvwhere
`within
`the network.
`The onlv centralized
`network component will be the DEAN located
`at
`the
`headend which is under the NAC’s
`control.
`and
`except
`For monitorins
`of
`packet veriFiers.
`its operation is P35”
`sive.
`
`4.2 NetwockuContcol_Nudes
`
`network
`There will be three tYPEE oF
`control
`nodes
`in MetroNet— the Network
`Access Controller.
`the Network TraFfic
`
`Monitor and Maintenance Node. and the Net—
`work Resource Manager.
`
`(NRC)
`The Network Access Controller
`under
`control of
`the network admini5m
`is
`tration and will
`allow it
`to
`restrict
`unauthorized
`users
`access
`to
`network
`resources.
`The maJor
`resource Protected
`is that oF network transport services.
`
`the
`bv
`The basic Function PerFormed
`is to Provide network channel access.
`NRC
`The Network Access Controller will main~
`tain one
`or more data bases containins a
`list oF valid user
`addresses.
`and
`user
`node
`10’s.
`The Network Access Controller
`can be located antwhere in the network but
`will
`be connected b? a set oF out 0F band
`channels to the head end.
`The use or
`out
`oF
`band channels between the NAC and BEAM
`will Prevent attacks on the DEAN bv mali~
`cious network users that would Prevent
`the
`DEAN From beins out oF communications with
`the
`NAB.
`The major PUPPOSE of
`the NAG is
`to dive the M50 control
`of
`the
`network.
`This
`"centralized"
`control
`function
`thoush. ma? be
`located anwwhere
`in
`the
`network.
`
`node
`control
`The next maJor network
`is the Network Traffic Monitor and Mainte~
`nance Node.
`A Network TraFFic Monitor
`(NTM) will
`be
`assigned
`to each network
`data channel.
`The network traFFic monitor
`will collect information on:
`
`statis~
`o source/destination node traFFic
`tics
`—
`these statistics will be used For
`accountins purposes
`
`throushrut and utilization.
`o data channel
`This
`information will
`be transmitted as
`necessarv to the NAC For traffic load lev“
`elins.
`
`NTM
`the
`it is ekrected that
`Furthermore.
`will
`be
`able
`to monitor individual node
`status and collect information about:
`0
`node up/down status
`0
`node throushput
`0
`node response time distribution
`
`pasr
`be
`the NTM will
`The actions of
`sive (except For its interactions with the
`NRM).
`It is anticipated that
`durins
`non
`peak business hours the NTM could consoli“
`date user usase and senerate network bil"
`lins
`information.
`A
`second Function oF
`the NTM will be to Perform analos measurem
`ments
`of
`individual
`channels. cable and
`amplifier qualitv.
`Network Monitorins
`probes will
`be
`situated throushout
`the
`network
`and
`interrosated as
`necessarv
`(over the data channels) be the NTM. This
`should allow the network administrator
`to
`detect
`network
`ststem Faults both beFore
`and after occurrance.
`It should be
`noted
`that these network probes could be used to
`detect acts ot
`vandalism (both
`thsical
`and electrical) asainst the network.
`The
`0F network status will perm
`>centralization
`mit cost efFective.
`implementation of net»
`work maintenance Policies.
`
`bv
`The last Function to be performed
`NTM
`node will be diaSnostics of net”
`the
`work equipment
`—
`both
`network
`control
`nodes
`and
`user nodes.
`IF administration
`costs
`are
`to
`be minimized.
`automatic
`remote
`diasnostic
`checks
`of
`equipment
`attached to the network will be necessarv.
`In
`some
`cases,
`the
`NTM will
`onlv
`be
`responsible for interrogating other net-
`work
`components
`or Seneratins test sis“
`nals. However.
`the NTM will
`be
`charsed
`with
`the
`reseonsibilitv of accumulating
`catalogins
`network diasnostic information.
`equipment as
`it.
`disablins Faultv network
`required. and reconfisurins the network to
`minimize
`the effect oF Failures or damase
`caused bY vandals. Like all MetroNet con“
`trol nodes the NTM can be located anvwhere
`within the network.
`
`28
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`

`

`The last control node to be discussed
`here
`is
`the Network Resource Manaser
`(NRM).
`The NRM.
`like both the NAC and
`NTM
`can
`be
`located anvwhere in the network.
`The NRM
`is accessed directlv bv a
`network
`and will allow:
`user node.
`
`bv
`connections
`o Network users to set up
`svmbolic.
`names without knowing the desti»
`nation address.
`
`0 Network users to interact directlv with
`the NRM.
`ie ~ directorv look up
`
`is
`It
`network
`the
`that
`expected
`will be responsible For the
`administrator
`The NHM will
`provide
`the
`NRM data base.
`allowins
`network
`users the
`basic
`tools
`abilitY to build their own directorv data
`bases
`for
`session set up throush the use
`0F svmbolic address names.
`
`4.3
`
`Netwonk-UseoMNodes
`
`consist
`The network user nodes will
`oF two ttpes. subscriber access and server
`nodes.
`The subscriber access nodes.
`(ter~
`minal). will
`be
`the most common in the
`network. The subscriber nodes will perForm
`the tollowins Functions:
`
`o Communication InterFace to MetroNet
`
`0 Data terminal
`
`the displav por~
`It is expected that
`tion For the terminal will be the standard
`home television receiver.
`The
`attachment
`of
`the
`data
`terminal will
`transform its
`Function from a simple TV receiver to that
`of
`a
`small
`Personal
`computer which can
`call upon the data
`and
`information
`ser-
`vices attached to MetroNet.
`
`the
`in
`interFace
`The communication
`terminal will provide the Followins Func"
`tions transparentlt to the user!
`
`m Interact with the NAC For channel access
`
`o Interact with the NRM For
`tiation
`
`session
`
`ini~
`
`o Interact
`manasement
`which
`to
`session
`
`o Maintain
`necessart
`
`network
`under
`select.
`and
`control.
`a data
`channel
`on
`operate
`For
`this
`Particular
`
`and
`
`disconnect
`
`sessions
`
`as
`
`an
`usins
`packets
`address
`and
`o Format
`internal MetroNet communications Protocol
`suite
`
`a Con