Case 1:16-cv-00455-RGA Document 32-2 Filed 10/21/16 Page 1 of 35 PagelD #: 1830
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`Case 1:16-cv-00455-RGA Document 32-2 Filed 10/21/16 Page 3 of 35 PagelD #: 1832
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`
`
`GHAP 1
`
`and software.
`ople ‘attached
`‘ent, and fre~
`| gatewaysto.
`in terms of
`is. called. an
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`y a WAN. In.
`>-qothing else
`veén a subnet
`systeni’ within
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`waysbe used
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`
`SEC, 13.
`
`NETWORKSOFTWARE
`
`17
`
`1.3.1.. Protocol Hierarchies
`
`To reduce their design complexity, mnost networks aré organized as a séries of
`layers. orlevels, eachone built upon the one belowit. The number of layers, the
`namé of each layer, the contents of each layer, and the function of each layer
`differ from network to network, However; in all networks, the purpose. of each
`layer is to offer certain. services: to the: higher layers, shielding those layers from
`the details ofhow the offered services are actually implemented.
`Layet #-on one machine carries. on a conversation with layer on: another
`machine; The rules and conventions usedin this: conversation. are collectively
`kitown-as the layer 2 protocol, Basically,.a protocol is an agreement between the”
`communicating parties on how communication is to: proceed; As an analogy,
`when 4 womanis introduced té-a man, she maychoose fo stick out her hand. He,
`in-turn, may-decide.-either toshake it of Kiss. it; depending, for example,on
`whether sheis-an American lawyer at a business meeting ora European princess:
`at a formal ball, Violating theprotocol will make communication more difficult,
`if not impossible:
`:
`‘The entities comprising the
`A five-layer networkis illustrated in Fig. 1-9.
`cotresponding layers on different machines. are called peers, In other words,it is.
`the peers that communicate: using the protocol.
`
`
`
`
`
`Host 2
`:
`Host-t
`: :ceLayer 6 protocol
`
`
`
`
`Layer 4/5 interface |
`er
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`Layer 4protocol
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`net makes the
`the collection
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`the. telephone.
`yther. by high-
`yese lines and
`
`s.subnet of the
`Layer3/4 interlace:
`
`*
`Layer 3 protocol
`
`oree
`alogy) are. not
`
`a network, In
`Layer 2/3 interface :
`re-reallyis no
`
`[Layer2Jenne-neeone
`
`id together. In
`Layer 1/2 interlace
`formsan inter-
`Layer 1 protocol
`°
`ry in this area.
`Layer} «+ s+ Bibb ae eee Pe
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`Layer 2 protocol
`
`
`
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`‘e. as the main
`3y- works: Net=
`ve examine the
`red here forms.
`
`Fig. 1-9. Layers, protocols, aad interfaces.
`
`In reality, no data are directly transferred. from layer.on one machine to
`layeron. another machine,
`Instead, cach.
`layer passes: data and control
`
`
`
`Physical medium |
`
`
`
`Patent Owner Acceleration Bay, LLC - Ex. 2046,p. 2
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`

`

`Case 1:16-cv-00455-RGA Document 32-2 Filed 10/21/16 Page 4 of 35 PagelD #: 1833
`
`28.
`
`INTRODUCTION
`
`CHAP.
`
`1
`
`até free to change their protocols at will, provided they donot change the service:
`visible.
`to: their users..
`In this way, the service and. the. protocol are completely
`decoupled,
`An analogy with programming languages is worth making... A service is like
`an abstract data type or an object in an object-oriented language. It defines-opera-
`tions that cai -bé performed on an objectbut does not specify how-these operations
`are implemented.
`-A protocol relates to, the. implementation of the.service and as
`such is not visible:to the user ofthe service.
`In
`Many older protocols did not distinguish the service. from theprotocol.
`effect, a typical layer might have: had a service. ptimitive SEND PACKET with the
`user providing a pointer to a fully-assenibled packet. This arrangement meant that
`all changes to’ the protocol were immediately visible to the users. Most network
`designers now regard stich a design as a-serious blunder.
`
`
`
`
`
`
`SEC.LA.
`
`‘Below w
`layer. Note-
`not specify t
`what each la
`layers, altho
`been publish
`
`Layer
`
`7 | Applic
`interface
`|
`
`
`Preser:
`
`1.4, REFERENCE MODELS
`Now that we have discussed layered networksin the abstract, it is time to look
`at some-examples,-In: the next two sections we will discuss two important: net»
`4
`Trane
`work architectures, the OSL refereiice model and the TCPAP reference. model:
`
`Neiw
`
`1
`
`peneoOAB
`
`
`
`
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`
`
`
`‘The Physica
`
`
`
`
`
`The phy
`cation chann
`sends al br
`
`
`
`
`
` Acceleration Bay, LLC - Ex. 2046, p. 3 .
`
`
`
`1.4.1. The OSI Reference Model
`‘The OSE model:is: shown in: Fig. 1-16 Gninus the physical medium), This
`model is based on a proposal déveloped: by the International Standards Organiza-
`tion. (ISO) .as-afirst.step towardinternationalstandardization ofthe protocols used.
`inthe various layers (DayandZimmermann,.1983)..The modelis called. the iso
`OSI (Open SystemsIntercomection) Reference Model. because it deals with.
`connecting open systems—that is, systems that. are open for communication with
`othersystéms,. We will usiiallyjust call it the OST model forshort.
`The OSI modelhas seven layers. The principles that were applied to arrive at
`the seven layers are as follows:
`:
`ty A layer: should. be. created where a. different level of abstraction-is
`feédéd,
`. Bach layer should performa well defined function,
`tw.
`4.
`‘The function ‘of each layer should be ‘chosen’ with an -éye toward
`defining intémiationally standardized protocols.
`4.. The layerboundaries should be chosen to minimize: the information
`flow across the interfaces.
`5., The numberof layers should be large enough thatdistinct functions
`need not bethrown together-in the same. layer out of necessity, and
`smallenough that:the architecture does not become unwieldy.
`
`Interface
`5
`
`ih
`
`Ses
`
`
`
`PhysfellelIpLlL.
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`

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`Case 1:16-cv-00455-RGA Document 32-2 Filed 10/21/16 Page 5 of 35 PagelD #: 1834
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`
`
`
`4i:
`
`CHAP.
`
`1
`
`'é the service
`a completely
`
`
`
`arvice is-like:
`efines opera-
`se operations:
`srvice and as:
`
`|
`
`29
`REFERENCE MODELS
`SEG. 14
`Below. we will discuss each layer of the model in.turn, starting at the bottom
`layer. Note that the OSI modelitself is not a networkarchitecture because it does
`rot specify the exact sérvices and protocols to be used: in each layer. It just tells
`what-each layer should do, However, ISO has also produced standards for all the
`layers, although these are not part of the reference modelitself. Each one has
`been published. as a separate international standard,
`
`:
`
`3
`
`Packet
`
`ad to arrive at
`
`raction-is
`
`Ik --|
`
`
`
`
`Physical
`"Host B
`
`Bit
`
`Layer
`Narne of unit
`axchanged
`
`In
`protocol.
`
`
`7|Application|~+-meeeaaacedaa Application|.APDU
`KET with the
`Interface
`,
`:
`|
`.
`nt meant:that
`
`Most network
`6|Presentation jx-----~---_Presentationprotocol~[Presentation pPDU
`
`interface
`:
`|
`|
`.
`éCee Session|SPDU
`3-time to look
`
`4|Tratisport..|}4-s+--7ee-7>aneportprotece!TRSASA- Transport|TPDU
`portant, net:
`e. model.
`Communication subnetboundary
`;[
`
`
`»
`~ fntetnal:-subnet protocol
`
`
`Network - as
`
`Network.)
`jen= ty Network: a
`Network
`
`
`sdium)..' This
`
`cds. Organiza-
`
`
`
`t
`Datalink | acoet Data link.|Frame
`
`wotocols used
`2-|
`Datalink: -<-:
`Datalink’.
`«=-f
`alled the ISO
`
`it deals with
`4 [ Physical =
`: Physical. lees Physical
`tnication. with
`Host A.
`Router
`Rouler
`Network layer hostrouter ptétocol
`
`. Dala link layerhost-vouter protocol
`Physical layer-host-router protocol
`
`ie toward
`
`formation.
`
`functions
`ssity, and
`ly.
`
`Fig. 1-16. The OSI reference model,
`
`The Physical Layer
`
`~The pliysical layer is concémed with transmitting raw bits over a communi-
`cationchannel. .The design issues: have to do with making sure that when one side
`sendsa 1 bit, it is received by the other side asad bit; not as.a-0 bit. Typical
`
`eeSLL
`
`ereLSBliceSERESt
`
`
`Patent Owner Acceleration Bay, LLC - Ex. 2046, p. 4
`
`

`

`Case 1:16-cv-00455-RGA Document 32-2 Filed 10/21/16 Page 6 of 35 PagelD #: 1835
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`36
`
` questions here are how many volts should be usedto representa1 and howtay
`
`
`
`
`The Data Link Layer
`
`
`INTRODUCTION
`CHAP,
`
`for a 0, how many. microseconds @ bit lasts, whether transmission may proceed
`simultaneously in both directions,. how. the initial connection is: established. and
`how-it is torn down when, both sides are finished, and how manypins the network
`connector has and what each pin is used for. The design issues here largely deal.
`with mechanical, electrical, and procedural: interfaces, arid. thephysical: transmis~
`sion medium, whichlies below thephysicallayer.
`
`
`
`
`Patent Owner Acceleration Bay, LLC -
`
`
`SEC. 1.4
`
`TheNetwor
`
`The net:
`Akey desig
`tion: Routes
`” farely chang
`example-a
`mined anew
`If-too mi
`each other's
`bélongs to th
`Since th
`efforts, .theré
`the very-leas
`sent-by cach
`national bor
`complicated.
`When.a.’
`tion, many. p
`be-different:
`because it is
`work layert¢
`intérconnecté
`In broad
`often thin of
`
`The Transp
`
`The: basi:
`layer, split it
`énsure that tl
`inustbe done
`itable.change
`Under: ne
`nection for-e
`port conkect
`create mutip
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`network con
`transport con,
`cases, the tra
`session layer.
`Thetrans
`
`
`
`
`
`
` i
`
`The main task of the data linklayer is to take a raw transiniission facility and
`transform it into-a line that appears free of Undétected trangniissionerrors: tothe.
`network layer. It accomplishesthis task by having the sender break the input data
`up into dataframes (typically a few hundred or a few thousand bytes), transmit
`the frames sequentially, and: process: the acknowledgement frames: Sent back. by
`the receiver. Since the physical layer merely accepts: and transmits a stream. of
`bits withoutany regard to meaning orstructiiré, it is up. to the dati linklayer to
`éréate and recognize frame boundaries. This can be accomplished by: attaching.
`special bit patterns. to ihe beginningand endofthe frame.
`Ifthese. bit patterns can.
`accidentally occurin-the data; special care must be taken, to’make sure. these pat=
`terns are not incorrectly interpreted as frame delimiters.
`In ihis. case, ‘the
`A noise. burst onthe lise can destroy .a frame completely,
`data link layer software on the source -machine-can retransmit the frame: How:
`ever; multiple wansmissions of the same frame introduce the possibility ofdupli-
`cate franes.. A duplicateframe could be sent if the acknowledgement frame. from:
`the receiver backto the sender wereJost. Itis up to this layerto. solve the-prob-
`leis catiséd by damaged, lost, and duplicate frames.
`"The data dink layer. may.
`offer several different service classes to the network. layer, each of-a-different
`quality and with a different price:
`Another issue thatarises. in the data link layer (and most of the higher layers
`as. well) is how’ to keep a fast-transmitter from, drowninga slowreceiver. in data,
`Sometraffic regulation mechanism must be employed. to-let the transmitter know’
`how much buffer space the receiver: has at the: moment. Frequently,.
`this:flow
`regulation dnd the érror handling: are integrated.
`Jfthe line can.be usedtotransmit data hi’ both directions,
`this ihthodtices 4
`new complication thatthe data link.layer softwaremust deal with, The problemis
`thatthe acknowledgementframes for Ato Btraffic compete for:‘the use of the line
`with dataframes for the B to Atraffic. A Clever solution (piggybacking) has been
`devised; we’ will discuss it in detail later.
`Broadcast networks have--an. additional issue in the data link layer: howto
`control access to the shared channel. A-special sublayer-ofthe datalink layer,the
`medium, Access sublayer; deals. with this problem,
`
`
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`Case 1:16-cv-00455-RGA Document 32-2 Filed 10/21/16 Page 7 of 35 PagelD #: 1836
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`
`
`CHAP.
`
`i
`
`d how emany
`nay proceed
`iblished- and:
`the network
`largely deal
`sal transmis:
`
`1 facility and
`errors tothe
`heinput data
`tes), transmit
`sent back by
`sa stveanti-of
`link layer. to
`by. attaching:
`i, patterns ‘can
`ye these pat-
`
`this case,. the
`frame... How-
`Hity ‘of duplt-
`it frame from
`ilve the prob-
`ak layer. may
`of ‘a-different
`
`higherlayers
`ceiver in- data,
`ismitter kiow.
`tly, this flow
`
`; Introduces a
`‘he problem is
`use. of theling
`ding) has been
`
`fo:
`layer: how:
`link layer, the
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`SEC. L4
`
`REBERENCE MODELS
`
`31
`
`The Network Layer
`The. networklayer is concerned with controlling the operation of the: subnet.
`A key design issue’ is determining how. packets are routed frony source :to'destina-
`tion; Routes carbebased on static tables that are “wired inte’” the network and
`rarely changed.
`‘T’hey cairalsobedetermined at thestart of each eotiversation, for
`example a terminal session, Finally, they can be highly dynamic, being: deter
`inined anewfor each packet,to reflect the current network load.
`If too many packets are present in thesubnetat the same time, they will get in.
`each ‘other's. way,. forming bottlenecks: The: control of such congestion. also:
`belongs to the network layer.
`—
`Since the operators of the subnet may well expect: remuneration for: their
`éfforts; there is ‘oftei gome. accounting function built inte thenetwork: layer. At
`the veryleast, the software must count how inany packets or characters orbils.are:
`sent by, each customer, to. produce billing information. When a packet.crosses a
`national border, with. different rates oneach side, the accounting can. become:
`complicated.
`a
`“Whena packet has to travel from one network (6atiother toget to its destina-
`‘tion, many problems can arise. The addressing used bythe:second. network. may
`be-different from the first one... The second. one ihay not-.accept the packet at all
`because it is. too large, The: protocols may differ, and so on, [tis up to thenet-
`work: layerto overcome all these problemsto allow heterogeneous networks to be
`interconnected.
`Cg .
`In bfoadcast networks, the routing problem. issimple, sothe network layer is
`often thin or even nonexistent.
`pes
`
`The Transport Layer
`“The basic. functioit ofthe transport Jayer is to: accept data from the session
`layer, split itup into smaller units }f need.be, passthese to. the network layer, and
`ensure: that the piecesall arrive correctly at the other end. Furthermore, all this:
`must be doneefficiently, and. ina way that isolates the upper Layers fromthe inev-
`itable changes.in thehardware technology.,
`oes
`a
`Under normal. conditions, the transport layer: creates.a distinct network con-
`nection for each transport connection required. by the session layer. If the brans-
`port connectionrequires. a high throughput, however, the transport layer might
`create inultiple network connections, dividing. the data among the network con-
`nections to improve throughput. On.
`the: other hand, if creating or maintaininga
`network, connection is expensive, the: transport
`layer might inultiplex: several
`transport connections onto thesame network connection to-reduce the. cost. In-all
`cases,.the transport layer isrequired to. make the multiplexing transparent to. the
`session layer.
`:
`ore
`oe
`The trarisport layer alsodetermines what type ofseivice toprovidethé session
`
`
`
`Patent Owner Acceleration Bay, LLC - Ex. 2046,p. 6
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`-
`
`CHAP. 1
`INTRODUCTION
`32°
`layer, ahd ultimately, theusersofthe network, The niostpopular type oftransport
`connection is an ettor-frée point-to-point channel that delivers messages or bytes
`inthe order in which they were sent). However, other possible kinds of transport
`‘service are. transportofisolated messages with no guarantee about the. order of
`delivery; and broadcasting of messages to multiple destinations. Thetype-ofser
`viceig determined wheil theconnection is established.-
`The transport layer is atrue end-to-erid layer, from, source fo destination.
`In
`other words, a program: on: the. source machine carries on-a conversation with a
`similar program on the destination machine,using the message headers and con-
`irol messages. In-the lower layers, the protocols are between each machineand its
`immediate neighbors, and not by the ultimate source and destination machines,
`which midy be separated. by many routers. The difference between layers. 1
`through. 3, which are chained, and layers 4 through7, which are end-to-end,-is
`illustrated in-Fig. 1-16.
`Many hosts aré multiprogrammed, which implies that multiple connections.
`will be entering and leaving each host, There tieeds to.be some way totell which.
`iiessage belongs to which connection. The. transport header (Hg in Fig. 1-11) is:
`one place.this information can be put.
`Cees
`ce
`In-addition to multiplexing several message streams onto one channel,. the
`transport layer must take care. ofestablishing and deleting ‘confections actoss.the
`nétwork.. This. requires some. kind of naming mechanism,so that. a process. onone,
`machine has-a way of describing with whomit wishesto converse. There must
`also -bea:mechanism toregulate the flowof information, so that.a fast host cannot
`overrunaslow one, Such a niéchanism is called: flow control andplays a key
`role. in. the transport layer (also’ in other layers). Flow control between hosts is
`distinet from flow control, between routers, although we will later see that similar
`principles apply to both.
`Thé Session Layer
`_
`“The session layer allows users of different: machines to éstablish sessions
`between them. A session allows ‘ordinary data. transport, as does:
`the: transport
`layer, butit also provides enhanced services useful in someapplications. A ses-
`sion might be used ‘to: allow a userto log into a remote timesharing system or. to
`transfera file between two machines.
`,
`a
`One of the servicesof the session layer is to mariage dialogue control. Ses-
`sions can allow traffic to .goitt both: directions at. the same: time,: orin: only one
`direction ata time:. If traffic ‘can only go one way at a time(analogous to-a single.
`railroadtrack), the sessionlayer can help.keep track of whose turn it is:
`Ac related ‘session’ sétvice. is token management, For some protocols, it is
`essential that both sides:do not attempt the same operation atthe samé time.
`‘To
`matiageé these activities, the session layer provides tokens that canbe exchanged.
`Onlythe sideholdingthe token may perform the eritical operation.
`
`
`
`
`
`
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`
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`
`
`SEC, 14
`~ Anothi
`mightocct
`l-hour me
`transfer -w
`time as we
`checkpoint
`after the la
`
`“The Prese
`,
`The p:
`ciently oft
`eachuser.
`just interes
`concerned
`A typi
`agreed upc
`They. exc:
`invoices;
`numbers,
`* puters“ hay
`Unicode),
`‘order tom
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`
`The Appli
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`nal that ec
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`
`
`
`
`Patent Owner Acceleration Bay, LLC - Ex. 2046, p.
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`

`

`Case 1:16-cv-00455-RGA Document 32-2 Filed 10/21/16 Page 9 of 35 PagelD #: 1838
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`
`
`SEC 14.
`REFERENCE MODELS
`~
`33:
`
`is. sytichronization.. Consider the problems: that
`Another session -service:
`mightoccur when tryingto do a 2-hourfile transfér betweentwo machines with a
`
`{-hour meantime. between ¢rashes:, Afler each transfer was aborted, the whole
`transfer would: bave to. start over again and would. probably fail again the next
`
`tireas well. Toeliminate this problem, the session layer provides a way to insert
`checkpoints into the data stream, so thatafter a crash, only. the data transferred
`
`after the.last checkpointhave tobe repeated.
`The Presentation Layer.
`
`
`The presentation layer. perfortns: certain functions. that are requested suffi-
`ciently. often to: warrant finding .a general solution for:them,. rather than: letting
`
`each user solve-the. problems.
`In particular, unlike allthe lower layers, which are
`justinterested. in movingbits reliably fromhere-to there, the piresentation. layer. is
`
`concerned withthe syntax and semantics oftheinformation transmitted:
`Atypical example: of & presentation service ig: encoding ‘data-in a standard
`
`agreed upon. way. Mostuserprograms do not exchange.randombinary bit strings.
`They exchange.
`things. siich as. people’s ‘names, dates; amounts: of money; and”
`
`invoices. These itemsare represented as charactersttings, integers, floating-point
`
`‘numbers,and data structares-composed ofseveral simpler items. Different :com-
`
`
`puters have different codes. for representing character. strings. (¢.g.; ASCID and
`Unicode),integers (€.g., one’s complement and two'scomplement), and so on. In
`‘Ordeto make it possible for computerswithdifferent repreesentations to commun-
`icate; the data structures to be exchanged can be defined inan abstr‘act way, along
`-with: astandard: encoding.
`tozbe: used “on the. wire.” The:presentation layer
`manages these:abstract datastructures and converts fromthe représentation. used
`
`insidethe computerto the network:standard representation and:back.
`
`The Application Layer.
`
`that. are. commonly
`The application layer contains a variety of protocols.
`needed, For example, there are hundreds of incompatible terminal types in. the
`world, Considertheplight ofa full screen: editorthatis: supposed tO. work over a
`network with many differént. terminaltypes, cach withdifferent screen, layouts,
`escape. sequences for insertingand deleting. text, moving thecursor, etc:
`Oneway. tosolve: this.problemiis.to define an-abstract network virtual termi-
`ynal that editors and other programs can be written to deal with. To handle each
`terminal type, a piécéof software mustbe written-to map the functions ofthe net~
`work Vittial terial onto.the real terminal. For example, whenthe editor moves.
`the virtual terminal’s cursor to. the upper left-hand® corner of: the screen,
`this.
`software. mustissue. the: proper commandsequence. to thereal terminal. to: get: its
`cursor theretoo. All the. virtual terminal softwareis in theapplicationlayer.
`Another application:layer function.iisfile transfer. Differentfile: systems have:
`
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`of transport
`iges or bytes
`of transport
`the order of
`+ type of ser-
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`There..must:
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`lis to a single
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`
`Patent Owner Acceleration Bay, LLC - Ex. 2046, p. 8
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`

`

`Case 1:16-cv-00455-RGA Document 32-2 Filed 10/21/16 Page 10 of 35 PagelD #: 1839
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`“1
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`34
`INTRODUCTION
`CHAP.
`
`
`different file naming coriventions, different ways of representing text lines, and so
`on, ‘Ttansferting a file between two different systems réquires handling these. and
`other incompatibilities.. This work, too, belongs.
`to. the application: layer,
`.as do
`electronic mail, remote job entry, directory lookup, and various: other general-
`purpose andspecial-purpose facilities.
`
`
`
`Data Transmission in the OSI Model
`
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`SEC, 1.4
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`headers. are
`it finally arr
`The key
`Fig: 1-17, e
`ingtratispor
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`view, ‘the fa
`own machit
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`to his transl;
`
`1.4.2. The’
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`The Interne
`
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`zsatNSRSSSI
`
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`Patent Owner Acceleration Bay, LLC - Ex. 2046, p. 9
`
`Figure 1-17 shows an example of how data can. be transmitted using the OSI
`model, “Ihe.sending process has some‘ data it: wants: to-sendto. the-receiving pro-
`cess, It gives the data to the application layer, which then attaches the application
`header, AH (which maybe null), to the front of it and gives the resulting item to
`the presentation layer,
`
`Sending
`
`
`
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`
`
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`Receiving
`Process
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`Let us-2
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`Application
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`Application protocol
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`fayer OPaa Jo, eet eu lee
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`layer.
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`was one of
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`Fig. 1-17, Ab example of how the OSI tiddel is used. Some of the headers may
`to real-time
`be null. (Source: H.C, Folts Used. with permission:
`
`
`The presentation layer may transform this item in vations ways aud possibly
`
`
`add-a header tothe front, giving the result to the session layer. It is important. to
`
`
`
`realize that the presentation: layer is not aware-of which portion of the data given
`All thes
`to itby the-application layer is AH, if any, and whichis true user data,
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`Ona comiec
`This process is repeateduntil the data reach the. physical layer, where. they are.
`
`the linchpin
`
`
`actually.transmitted’ to. the receiving machine. On that qachine.. tlie. various
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`Case 1:16-cv-00455-RGA Document 32-2 Filed 10/21/16 Page 11 of 35 PagelD #: 1840
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`SECO16
`EXAMPLE DATA COMMUNICATION SERVICES
`59.
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`CHAP? 4
`
`», Jeased Jines
`them. With’
`- 1)/2-possibly
`re short. access
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`: must be -fast
`netinies lower.
`ut they are not
`yone company
`LAN’ 4; which
`¥ connects fo.a
`dS network as
`hés-in thepro-
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`livery. service,
`‘he: destination
`ole: lengthpay-
`esending- LAN
`ne, and SMDS
`Yo guarantee. 18
`
`
`
`
`Av additional:-user feature is address screening, on both outgoing and iicem-
`jig packets. With outgoing screening, the customer can give alist of telephone
`puimbers and: specify that no packéts: may. bé sent to any. other addresses. “With
`yicoiming screening, only packets from’certain pre-arranged. telephone nurbers
`“will be: accepted... When both features are enabled, the user can effectively build a
`private network with noSMDS connectionsto the outside world. Focompanies
`with confidential data,this feature is highly valuable.
`Thepayload can contain any. byté sequencethe user wishes,upto 9188 bytes..
`SMDS. does not look. atic.
`It. can containan Ethernet packet, an IBM‘token tig
`packet, an IP packet, or anything.else. Whatever-is present in the payload fieldiis
`moved without modificationfrontthe source LANto the destination LAN,
`SMDS.haindles bursty traffic as follows. The router connectedto éach adcess
`line contains a countéer that is, inctemented-at a-constant-rate, say once every 10
`usec, Whenapacket arrives at the router, a check is made to see if the counteris
`ereater. (han the packet length, in bytes. If itis, the packet is sent without delay
`and ihe. counter is decfemented by. the packet Tehgth: If the packet: length is
`greater thanthe counter; the packet is discarded.
`"Tneffect, with a tick every 10 psec the user may. send af an average rate of
`100,000 bytes/sec, but the burstrate may. be.muchhigher: If, for example, the line
`fias been idlefor 10 msec,the counter will be 1000; and the wiser willbe allowed
`to send a 1-kilobyte burstat the full 45 Mbps, so it-will be transmitted 1in about
`180 psec. Witha 100,000 byte/sec leased line, the same ‘kilobyte. would take-.10
`msec. Thiis SMDS-offers short delays for widely spacedindependent data bursts,
`as long asthe average. fate. remains below the agreed uponvalue. This mechan-
`ism provides fast response. when ‘needed. but: prevents: users. from using up more
`bandwidth than’ they have agreed. to. payfor.
`
`
`
`|4
`
`followed “by. a
`iia separate. 4:
`and subscriber:
`Tt was thought -
`J make the new
`
`chécks.to make.
`prévent billing
`If it is correct,
`
`specifyalist oF
`‘ the whole. list.
`i that list, The
`cl's: SMDS- ser-
`
`156.2. X25 Networks
`Many: older public networks, especially outside the United. States, follow.a
`standard called’X.25.-It was developed duringthe 1970s: by ecrr"Eto providean
`interface between public packet-switchednetworks and their-customers..
`‘The. physical layer protocol, calledX.21, specifies. the-physical, electrical, and
`procedural‘interface between the host and the network...Very few public networks
`actually. support this standard, because it requires digital, rather thal analog sig-
`naling‘onthe telephone: lines: Asaninterim measure, an analog interface similar
`to the familiar RS-232 standard wasdefined:
`Thedata linklayer standard bas a number of(slightly jacompatible) varia:
`tions. Theyall aredesigned to deal. with transmissionerrors onthe telephone: line
`between the'user’s equipment: (host or terminal) and the public network: (router).
`The networklayer protocol deals with addressing, flow control, delivery con-
`firtnation, interrupts, and: velated issues. Basically, it-allows. theuser to establish
`virtual circuits and then send packets ofipto 128 bytes on them.- These packets:
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`Patent Owner Acceleration Bay, LLC - Ex. 2046, p. 10
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`Case 1:16-cv-00455-RGA Document 32-2 Filed 10/21/16 Page 12 of 35 PagelD #: 1841
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`60
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`CHAP:
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`1
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`SEC. 1.6
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`INTRODUCTION
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`Usage. miist: be
`are delivered reliably. and in order. Most 25 networks work at speeds tip-to 64
`kbps, which makes them obsolete for many purposes. Nevertheless; they aré still
`less fot a virtu
`— Tn-additios
`widespread, so-readersshould be aware of their-existence:
`X.25 permane
`X25 is connection-oriented and supports. both switched virtualcircuits and
`15 Mbps, and:
`- permanent ones. A switched virtualcircuitis éyeated: when one. computer sends
`Frame reli
`a-packet to the network asking to-makea call to.a remote computer... Once.estab-
`lished, packets can besent over thé connection, always arriving imorder. X05
`start and énd.c
`received, the-f
`provides flow control, to.make sure-a fast sender’ cannot swamp a slow or busy
`that-aframe i
`receiver.
`frame relay dc
`Apermanentyirtual circuitis used the same. way as a switched one, botitis
`haveabit in.t
`set up in. advance.by agreemient between the customer and the-carrier.. It is always
`
`cate to the othi
`présent; arid no call setupis required to use it. It is analogous to a leasédline.
`-. Because the world is still full of terminals that do not speak. X25, anotherset
`of standards’ was defined that describeshow. an ordinary (nonintelligent) terminal
`cotimunicates withan X.25 public network,
`In effect, the user or network opera-
`tor installs a “black. box” to. which thése termitials can connect. The black box ig
`called a PAD(Packet Assembler Disassembler), andits function. is described in
`‘a document known as:X.3. A standard, protocol has been defined between the ter-
`minal and the PAD, called X.28; another standard protocol exists between: the
`PAD ahd the network, called X.29. Together, thesethree. recommendations: are
`often called triple X..
`
`LGA. Broad
`
`Even if. th
`facedwith afe
`Telephone Set
`new data: servi
`network: DOL
`management:
`1
`separate netwe
`sion, that thet
`_ The: percei
`will replace th
`single integrat
`will havea hu;
`make if possib
`ect, and'it is ce
`The new.*
`vices Digital:D
`sources; full nv
`connection, hig
`vices thathave
`The under
`(Asynehronoy
`clock), as: mas
`here has: nothi
`(although an/A
`A great dei
`tem that rises ¢
`ject, see (Piset
`Kyas,. 1995; M
`
`
`
`
`
`1.6.3. Frame Relay
`
`Frame relay: isa. setvice for people. who “want: an absolute. bare-bones
`conhection-oriented way to move. bits. from Ato. B at reasonable. speed and low
`cast (Smith, 1993)... Its existericé is dué to changes in technology over the past
`two. decades: “Twenty years ago, communication using telephone: lines“was slow,
`analog,and unreliable, and computers..were slow and expensive. As result,
`complex protocols were required to maskerrors,and the users’. computérs’ Were.
`{0 expeiisive to havethem do this work.
`telephone. lines. are now fast,
`The sittiation: has changed radically.. Leased.
`digital, and reliable, and computers are fast and:inexpensive. This suggests the.
`use of simple protocols, with mostof the work being done by the users’ comput:
`ers, rather than by the network. Itis this environmentthat frame. telay -addrésses.
`Frame relay can best. be thought of asa virtual. leased line, The customer:
`‘Jedses a-permanent virtual circuit between two points and can then send franiés
`(ie., packets) of up to 1600 bytes between them. It is-also. possible to lease. per-
`manent -vittual- circuits. between. a given, site. and. multiple ‘Other sites; so each.
`frame carries a 10-bit numbertelling whichvirtual cticuit to. ise:
`The difference. between an actualleased line and. a virtual leasedline is that
`with anactual one, the tiser can-send. traffic all day long: at the maximum speed.
`With.a virtual one, data bursts may be-sent at full speed, but the long-termaverage
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`Patent Owner Acceleration Bay,