||||||||||||||||||l|||||||||||||||||||l||||||||||l||||||||||l||||||||||||||
`USUU66U3757Bl
`
`(in) Patent No.:
`(45) Date of Patent:
`
`US 6,603,757 B1
`Aug. 5, 2003
`
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`Assr'.s'.r.:m.' .EA'mrIi:1er—-l(eilh M. George
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`(57)
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`ABSTR/\CT
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`Apparalus operable as a standalone, open programmable
`-
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`[VDAC] card for providing voice over ll-’ (lnlernel protocol]
`capalmility. Tlie VDA(.‘ card in::lude.<; an array of digital
`signal prraeessors (l)Sl’s) which may be programmed lo
`perform desired prolncol conversions helween circuil-lwasccl
`proluctals, such as T1. E1 or Jl, and packel—l'Ja5sed pr0l0(:0‘|.<;,
`such as ll’. The apparalus Is scalable and may readily
`incorporate olher Cards which pmvidc bmh subs”-il,c,
`suPl3lcmcr1larv services and network signalling as required
`10 men! The needs of a particular application.
`
`4 Claims, 4 Ilrawlng Sheets
`
`C
`(.2) United States Patent
`Locaseio
`
`(54) VOICE-DATAACCESS CONCENTRATOR
`]r()R N();){e; [N AN [«;x[)AN|}A];]J|.~‘
`TELECOMMUN[CA'}‘[ONS Sy§']‘]_r_M
`
`(75)
`
`Inventor:
`
`Tllllglflthj’ Ray Locasciu, Uslerville. MA
`(
`)
`(73) Assigneez Excel Switching Corporation,
`Hyannias. MA (US)
`
`( " ) Nuliccl
`
`Suhjecl E0 any Llisclaimer. [he lerm of this.
`palcnl
`is extended or adjuasled under 35
`U.S.C. l54(b)l1y[Ida)rs.
`
`(21) App]. No.1 l]9;’291,889
`
`Filed:
`
`Apr. [4, 1999
`
`(22)
`.
`-
`Int U-7 ---------------------------------------------- .- H041. 1366
`(31)
`(52) U.S. Cl.
`379,852" 3?().*'4Ul
`__
`_
`I’
`-
`
`(53)
`1"“'d 0‘ 3°‘“""h
`37“»'352- 353-
`37w-E4! 355» 3555 455‘ 455
`
`
`
`References Cited
`U5‘ pA']‘EN']’ [)(){_jUM]_:_N‘fS
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`FIEDUNDANT
`303 SWETCHING BUSES 30b
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`443
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`CIFICUIT-BAS ED
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`HEDUNDANT587
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`SS7
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`001
`
`Apple 1013
`Apple 1013
`U.S. Pat. 8,995,433
`U.S. Pat. 8,995,433
`
`001
`
`

`
`..lHe4....aPcwU
`
`Aug. 5, 2003
`
`Sheet 1 of4
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`US 6,603,757 B1
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`U.S. Patent
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`Aug. 5, 2003
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`Sheet 2 of4
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`U.S. Patent
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`Aug. 5, 2003
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`

`
`US 6,603,753’ B1
`
`1
`VOICE-DATA ACCESS CONCENTRATOR
`FOR NODIC IN AN EXPANDABLIS
`TEI..[£C()MMUNICA’l‘I()NS SYSTICM
`
`BACKGROUND OF TI-IE INVI:iN'I'ION
`
`1. Field of the Invention
`
`invention relates generally to the field of
`The present
`telecommunications and, more specifically, to a program-
`mable telecommunications switch which is operable as a
`node in an expandable telecommunications system and
`includes an interface for conducting telecommunications
`over the Internet.
`2. Discussion of the Related Art
`
`Ill
`
`15
`
`2
`based network, while the other side of the interface connects
`with the switch's internal bus structure over which the
`interface and other circuitry within the switch may commu-
`nicate.
`
`The present invention permits a CLEC. system integrator
`or other customer to introduce VoIP capability as either an
`addition to an existing network (e.g., PSTN) or through the
`construction ofa new network as desired. In either case, the
`present invention allows the introduction of Vol? capability
`in the locations and amounts needed to satisfy demand.
`Future growth in demand for such capacity is flexibly
`accommodated by simply including additional
`interfaces
`within the switch or adding additional nodes as the case may
`be. If desired, multiple interfaces may be concentrated in a
`single node whose VolP capability is fully accessible by the
`other nodes of the expandable telecommunications system.
`Similar considerations apply to using the present invention
`to provide communications based on protocols other than IP.
`In addition, traditional telephony services and functions,
`including both supplementary services (conferencing, Qall
`waiting, voicemail, etc.) and network signalling (tone
`detection, tone generation. etc.), as well as new services,
`may be provided within the same programmable switch
`which includes a VoIP capability or within other nodes that
`are part of the same expandable telecommunications system.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The invention description below refers to the accompa-
`nying drawings, of which:
`FIG. 1 is block diagram of a programmable telecommu-
`nication switch which is operable as a standalone device, a
`node in an expandable telecommunications system or as a
`gateway, and which is constructed in accordance with a
`preferred embodiment of the present invention; and
`FIGS. 2A—2C together form a block diagram of the
`voicefdata access concentrator card of FIG. I in further
`detail
`in accordance with a preferred embodiment of the
`invention.
`
`DETAILED DESCRIPTION OF AN
`ILLUSTRATIVE EMBODIMENT
`
`I shows the major functional components of a
`FIG.
`preferred embodiment of a programmable telecommunica-
`tions switch 2 in which the present
`invention may be
`implemented. Circuit—based networkfline interfaces 4, which
`may represent links to a public switched telephone network
`(I’S’IN) or private circuit-basedtcircuit-switched network
`(or both), are provided by a series of line card inputfoutput
`(ID) cards 20.
`If desired, a
`redundant
`IO card 22 and
`redundant IO bus 24 may optionally be included.
`One or more digital network (Tl, E1 or J1) or analog
`trunkfline line cards 26 communicate with 10 cards 20 over
`line card (LC) 10 lines 28. Line cards 26 are also connected
`in communicating relationship with redundant switching
`buses 30:: and 30!). Again, if desired, one or more redundant
`line cards 32 may be provided, such redundant line cards
`arranged to communicate with a redundant IO card 22 over
`redundant LC 10 lines 34.
`
`If desired, diverse, programmable communications ser-
`vices such as tone detection and generation, sub-rate
`switching, conferencing, voice recorded announcements,
`call progress analysis. speech recognition, ADPCM
`compression,
`interactive voice response (IVR) and many
`others may he provided by one or more multifunction digital
`signal processing (MFDSP) cards 36 and optional redundant
`cards.
`
`'
`
`30
`
`With the goal of providing telecommunication services at
`lower prices than those charged by long distance carriers,
`competitive local exchange carriers (C'[.ECs} and
`govemment-controlled telephone companies, an effort
`is
`underway to use the Internet to carry voice traffic which has
`traditionally been carried by the public switched telephone
`network (PSTN). This type of application or service is often
`referred to as “voice over IP" (VoIP) where “lP" refers to
`Internet protocol.
`Several important considerations arise in connection with *
`the development of VoIP including determining how much,
`if any, of a communication path from a given subscriber to
`another should be provided by the PSTN and how much
`should be provided by the Internet. In other words, should a
`subscriber’s communication device interface directly with
`the Internet (meaning that subscribers must be equipped
`with “Internet telephones,” l’Cs which include telephone
`functionality or the like), or should the PSTN be used to
`connect subscribers (who would continue to use conven-
`tional telephone scts) to the Internet through a gateway or
`similar device. Of course, other scenarios are possible as
`well, and it is likely that a mixed or hybrid infrastructure will
`exist for a long time because of the prohibitive cost of
`constructing or replacing networks as well as replacing
`subscriber equipment.
`Another consideration is how to provide supplementary or
`enhanced services to subscribers who will not want
`to
`sacrifice call forwarding, call—waitirtg, voicemail, confer-
`ence calling and other existing services merely to obtain
`lower cost Internet-based phone service. Further, there is
`great need for system flexibility to allow rapid, inexpensive
`development and introduction of new services,
`largely
`because such new services provide large revenue growth
`potential for most carriers.
`A third consideration is system capacity and scalability.
`Because of the dilficulty in accurately forecasting both the
`demand for additional telecommunication bandwidth and
`the rate at which subscribers will migrate to Internet-based
`telephony,
`it
`is extremely important
`that any system be
`capable of rapid, large-scale expansion without significant
`disruption of service and without forcing large initial invest-
`ment for capacity that may not be needed for a long time.
`
`35
`
`40
`
`45
`
`50
`
`55
`
`SUMMARY OF THE INVENTION
`
`In brief summary, the present invention provides a pro-
`grammable telecommunication switch, operable as a node in
`an expandable telecommunications system, as a standalone
`switch. or as a gateway. The programmable switch includes
`an interface, sometimes referred to as a voicefdata concen-
`trator card, for conducting VoIP communications. One side
`of the interface connects to the Internet or other packet-
`
`60
`
`65
`
`006
`
`006
`
`

`
`US 6,603,753’ B1
`
`3
`If desired, a Signalling System No. 7 (S57) card 38
`supports communications over networkfline interfaces 4
`using the SS? protocol. As noted above with respect to other
`types of cards, one or more optional redundant SS7 cards 38
`may he provided within switch 2.
`One or more voicefdata access concentrator (VDAC)
`cards 48 (which may include an optional n+1 VDAC card)
`are connected in communicating relationship with switching
`buses 30:1 and 30b. VDAC cards 48 provide packet-based
`network interfaces 50 for connection with the Internet (not
`shown) or other packet-based networks whose communica-
`tion protocols are supported by cards 48.
`It should be understood that by providing other types of
`cards within switch 2, other communication protocols such
`as ISDN, DS3, SONET, ATM or others may also be sup-
`ported by switch 2.
`Control of the operations ofswitch 2, as well as the actual
`switching functions, are performed by either a CPUr'rnatrix
`card or nodal switch 440. If a CPUt‘matrix card is used,
`switch 2 may operate essentially as a standalone device (i.e.,
`as opposed to operating as a switching node in an expand-
`able telecommunications system, described below) or as a
`gateway between PSTN rtetworkfline interfaces 4 and
`packet-switched network interfaces 50. In that case,
`the
`Cl’Ulmatrix card 440 may be connected to a host interface ‘
`42:: through which communications with an external host
`device (not shown) are effected. Typically, but not
`necessarily, the overall operations of switch 2 are controlled
`by an application program running on the host device.
`Alternatively, if a nodal switch is used, switch 2 may
`operate as a node in an expandable telecommunications
`system, an example of which is described in U.S. Pat. No.
`5,544,163 which is hereby incorporated by reference. In
`such an embodiment,
`the nodal switch 44a is preferably
`connected with a ring 10 card 40:? through which commu-
`nications with an inter-nodal network 12:: are effected.
`lnter—nodal network 120 is preferably implemented with one
`or more fiber optic rings. Inter-nodal network 12!:
`is a
`redundant set of one or more fiber optic rings. The nodal
`switch 44:: may also communicate with an extemal host via
`host interface 420.
`
`ill
`
`15
`
`30
`
`35
`
`40
`
`Regardless of whether a CPU;‘matrix card or a nodal
`switch is selected, a matching standby CPUfmatrix card or
`nodal switch 44!: may optionally be provided and accom-
`panied by the appropriate host interface 42b or ring 10 card
`40b (or both). In such a configuration, a link 46 is provided
`for direct communication between active and standby
`devices 440 and 44b.
`
`Details of the construction and operation of an exemplary
`C PUfn"tatrix card, as well as switching buses 30:: and 30b,
`may be found in U.S. Pat. No. 5,349,579 which is hereby
`incorporated by reference. Similarly, details of the construc-
`tion and operation of an exemplary nodal switch may be
`found in the above-referenced U.S. Pat. No. 5,544,163.
`FIG. 2 is a detailed block diagram of VDAC card 48
`shown in FIG. 1. An ethemet switch 54 provides dual
`network interfaces 50 which are capable of operating at 100
`Mbitfsec. Ethernet switch 54 is interfaced with a CPU 52,
`which is preferably a Motorola M(T86U, that controls overall
`operation of VDAC card 48. CPU 52 communicates over
`dual 1-IDLC buses which are part of switching buses 30:: and
`30!).
`
`A local control map 56, which is under the control of CPU
`52, operates in conjunction with a time division multiplex
`(TDM) bus switch 58,
`to time switch data (timeslots)
`between switching buses 3051 and 30b and VDAC.‘ card 48.
`
`45
`
`50
`
`55
`
`60
`
`0'5
`
`007
`
`4
`Tirneslots which is are received from buses 30:: and 30b, via
`TDM bus switch 58, are passed to PCM memory 60 and then
`to PCM;”module switch 62, whose operation is controlled by
`module control map 64.
`As the tirneslots are passed through switch 62, they are
`routed to one of eight Texas Instruments 'l‘I320C549 Digital
`Signal Processors (DSPS) 80a—-80d on one of four VoIP
`daughter cards (each is denoted by a dashed line box). Each
`daughter card includes eight DSPs [and their] 8l]rr-—80d, each
`with its own external SRAM 8ln—8ld. The DSPs are
`memory mapped into the address space of a Motorola
`MC850 processor '74rr—-740', used to control the operation of
`the daughter card, which has its own local SDRAM 78n—78a'
`and flash memory {not shown). Each processor 74rr—74a' has
`a 10 Mbitlsec full duplex [ethernet]|'-Lthernet pipe to
`[etherrtet]Ethernet switch 54 which allows for communica-
`tion among all of the daughter cards, CPU 52 and the
`external IP network.
`
`CPU 52 is also connected in communicating relationship
`with external bus arbitration logic 66, external bus bullers
`68, SDRAM 70 and flash memory 72.
`In general, VDAC card 48 functions to provide intemet—
`working between packcbswitched or packet-based commu-
`nication protocols (e.g., ll’) that are typically used to effect
`communications over network interfaces 50. and circuit-
`switched or circuit-based communication protocols {i.e., T1,
`E1 or J1) that are typically used to effect communications
`over networkfline interfaces 4 (FIG. 1}. DSPs 74a-74d,
`along with their related circuitry, operate to perform the
`necessary steps,
`including packetizing and depacketizing,
`digital processing of data and the like, to convert from one
`protocol
`to another. For example, by loading appropriate
`software into memories 70 and 72, CPU 52 may simulta-
`neously run H.323, H.225 ((3.931) and H.345 protocols or a
`variety of other protocols chosen to meet
`the needs of a
`particular application, thereby enabling. VDAC card 48 to
`support communications which use any of those protocols.
`Such protocol software may he obtained from commercial
`sources, one such source for H.323 software being RAD-
`Vision Inc. of Mahwah, NJ.
`With reference to FIGS. 1 and 2A—2C, an example of the
`protocol conversion that may be performed will now be
`described. Assure that one or more T1 spans are connected
`to circuit-based networloline interfaces 4. Further assume
`that packet—base»:| network interfaces 50 are connected to the
`Internet for the purpose of providing VoIP service within
`switch 2. As timeslots {e.g., PCM data} which are destined
`for the Internet arrive at T1 line cards 26 (or smart line cards
`32), they are transmitted over switching buses 300 and 30b
`to TDM bus switch 58 on VD/\C card 48. TDM bus switch
`58 time switches those time slots to PCM memory 60, from
`which they pass through PCMtmodule switch 62 and then to
`designated areas of DSI’ external SRAM Slrr—81d. Once
`stored in SRAM 81n—8ld, the timeslols are available for
`processing by the respective one of DSPS [74a—74d]
`80ar—8l]d that has access to such SR/\M. Such processing
`may typically include packetization of the timeslots as data
`within IP packets, which packets are then passed via the
`processor 74a—74d through the [ethernet] Ethernet buses
`82rr~82d to [ethemet] Ethernet switch 54 for transmission to
`the Internet.
`
`It will be understood by those skilled in the art that VDAC.‘
`card 48 may also perform a protocol conversion which is
`essentially the reverse of the process just described, that is,
`receiving Internet packets containing timeslots at ethemet
`switch 54, depaeketizing the timeslots. and passing those
`
`007
`
`

`
`US 6,603,757 B1
`
`5
`timeslots via TDM bus switch 58 to switching buses 30a and
`30!), over which such timeslots may be passed to line cards
`26. MFDSP cards 36. SS7 cards 38 CPUr‘matrix cards or
`nodal switches 44a and 44b.
`
`6
`converting information received through said packet-
`switched network into circuit-switched data and con-
`verting circuit-switclied data into information for trans-
`mission through said packet-switched network
`whereby the switching node Provides internetworking
`between a circuit~switched protocol and a packet-
`switched protocol, including sending voice over Inter-
`net information therebetween, and
`said voice data access concentrator card having associated
`therewith an Ethernet switch that provides dual network
`interfaces with said one or more packet-switched networks.
`and said Ethernet switch having an associated CPU to
`control operation of said card, and said associated CPU
`being in communicating relationship with components in
`said switching node over dual I-IDLC buses incorporated
`into redundant internal switching buses in said switching
`node.
`2. The switching node as defined in claim I
`comprising
`a local control map, which is under the control of said
`CPU associated with said Ethernet switch, said local
`control map operating in conjunction with a time
`division multiplex (TDM) bus switch for
`time-
`switching tirneslots between internal switching buses
`of said switching node and said voice data access
`concentrator card.
`
`further
`
`3. The switching node as defined in claim 2 further
`comprising:
`a plurality of VoIP daughter cards, each including:
`(i) at least one of said digital signal processors; and
`(ii) an external memory storage device associated with
`each digital signal processor, and said digital signal
`processors are memory mapped into an address
`space of an associated processor that is programmed
`to control operation of the daughter card with which
`it
`is associated, said processor also having a full
`duplex Ethernet pipe to Ethernet switch 54 for com-
`munication among said daughter cards, the CPU and
`said packet-switched 11’ network.
`4. The switching node as defined in claim 1, wherein said
`node is a services node that is adapted to provide at least one
`of the following: a) a voice mail services; b) interactive
`voice response services; c) voice messaging services; d) call
`waiting; e} wireless communications services; c) personal
`communications services PCS; and D conferencing.
`9l=
`=0!
`it
`it
`it
`
`The foregoing description has heen limited to a specific
`embodiment of this invention. It will be apparent, however,
`that variations and modifications may be made to the
`invention, with the attainment of some or all of the advan-
`tages of the invention. Therefore,
`it
`is the object of the
`appended claims to cover all such variations and modifica-
`tions as come within the true spirit and scope of the
`invention.
`What
`is claimed as new and desired to be secured by
`Letters Patent of the United States is:
`1. Apparatus operable as a switching node in an expand-
`ahle telecommunications system, which system includes a
`plurality of switching nodes interconnected by an associated
`inter-nodal network, each switching node being capable of
`dynamically connecting or disconnecting communications
`paths with respect to various ones of a plurality of ports, said
`switching node comprising:
`(A) one or more nodal switches each of which includes
`circuitry for transmitting and receiving information
`over the inter-nodal network to which the switching
`node and other nodes of said system are connected in *
`communicating relationship, and said nodal switch
`including a time switch for time-switching information
`in time slots to or from said ports, and including
`circuitry for transmitting and receiving information in
`time slots in a packet over the internodal network to
`which said switching node and other switching nodes
`are connected in a communicating relationship;
`(B) one or more line cards, connected in communicating
`relationship with said one or more nodes for interfacing
`the node with one or more circuit-switched networks
`over which communications are conducted using
`circuit-switched protocols; and
`(C) a voiceldata access concentrator card, connected in
`communicating relationship with said one or more
`nodal switches, and that includes an interface to one or
`more packet-switched networks over which communi-
`cations are conducted using packet—switched protocols
`including Internet protocol, said interface including one
`or more digital signal processors for converting infor-
`mation bctween said circuit-switched protocols and
`said packet-switched protocols,
`including means for
`
`IE)
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`15
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`3-0
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`35
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`40
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`45
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`008
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`008