Ulllted States Patent
`
`[19]
`
`[11] Patent Number:
`
`6,084,881
`
`Fosmark et al.
`
`[45] Date of Patent:
`
`Jul. 4, 2000
`
`US006084881A
`
`....................... .. 370/395
`4/1997 Oskouy et al.
`5,625,625
`370/233
`5/1997 Hayter et al.
`5,629,937
`370/232
`5,701,292 12/1997 Chi11SSi 61 a1-
`370/382
`5,726,985
`3/1998 Daniel et al.
`39357/§§)2()a(6)
`.........................
`‘Z’:/<:1I1gge<:taa1.
`.. ...
`... .. 370/395
`5/1998 R h
`1
`12/1998 al. ...................... 379/93.14
`
`
`
`--
`
`527512709
`5,852,655
`
`FOREIGN PATENT DOCUMENTS
`
`0 130 260A1
`0 325 794A2
`
`9/1985 European Pat. Off.
`2/1989 European Pat. Off.
`
`........ .. H04L 5/14
`..... .. H04Q 11/04
`
`OTHER PUBLICATIONS
`T h ~
`«ATM
`W“
`0mm.
`3 ’“Ima Wm“
`Recommendations, Mar. 1997.
`ADSL Forum WT—004 V. 3.0, Framing and Encapsulations
`Standards for ADSL: Packet Mode, Mar. 1977.
`
`Primary Exami/1er—Chau Nguyen
`Assistant Exammer—I-Gm T. Nguyen
`A1101"62 Agent’ or F”’"_Bak‘°’r & B0115’ LLB
`[57]
`ABSTRACT
`
`A multiple mode XDSL interface (60) is disclosed. The
`multiple mode XDSL interface (60) includes an XDSL ter-
`mination unit
`Operable to Couple to an
`-
`-
`“ad 1°1IE1a“ag‘;i::°mIT1:‘T’at1°I:1°fDd§‘E‘.iC“ESS MEOXDISL
`1’ V51“
`aye“
`9 mu 1 P 9 111° 9 X
`1“ 91 a°‘°*(
`) a 59
`includes a customer premises equipment (CPE) termination
`unit (65) coupled to the XDSL termination unit (62) and
`operable to couple to customer premises equipment. The
`CPE termination unit (65) has an operating mode selected
`from a plurality of operating modes Where each operating
`mode is associated with a data protocol and supports com-
`munication of data across the XDSLphySiCa1 layer using the
`associated data protocol
`'
`
`26 Claims, 2 Drawing Sheets
`
`[54] MULTIPLE MODE XDSL INTERFACE
`
`[75]
`
`Inventors: Klaus S. Fosmark, Plano; Kevin S.
`Dibble; William A_ perry, Jr” both of
`Carromona all of Tex.
`.
`.
`1731 Asslgneei Efficlem Networks’ Inc” Dallas’ Tex"
`
`[21] Appl, No; 03/351,573
`
`[22]
`
`Filed;
`
`May 22, 1997
`
`Int. Cl.7 ................................................... .. H04L 12/28
`[51]
`[52] U.s. Cl.
`........................................... .. 370/397; 370/466
`Of Search ................................... ..
`3mB%;wz4w¢M04%,%54%,
`467’ 360’ 469’ 420
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`7/1993 Buhrke et al.
`5 231 631
`.......................... .. 370/60
`5,274,768 12/1993 Traw et al.
`395/275
`5,280,476
`1/1994 Kojima et al.
`.. 370/60.1
`5,311,509
`5/1994 Heddes et al.
`370/60
`5,379,297
`1/1995 G10V6f61a1~
`~~ 370/601
`
`- - ~ - - -
`5,381,411
`1/1995 011110 61 91-
`- - ~ ~~ 370/60
`5,414,707
`5/1995 Johnston et al.
`........................ .. 370/79
`5,420,858
`5/1995 Marshall et al.
`..................... .. 370/60.1
`5,430,721
`7/1995 Dumas etal.
`.. 370/60.1
`5,455,826
`10/1995 Ozveren et al.
`370/60
`5,490,141
`2/1996 Lai et al.
`....N
`N 370/60.1
`5,535,197
`7/1996 Cotton . . . . . . . . . .
`. . . . N 370/60
`5,548,587
`8/1996 Bailey et al.
`........................ .. 370/60.1
`5,557,607
`9/1996 Holden ................................. .. 370/58.2
`5,568,486
`10/1996 Huscroft et al.
`.. 370/94.2
`5572522 11/1996 Ca1amV°k15 61 31-
`~- 370/691
`5,583,861
`12/1996 Holden ................... ..
`370/395
`5,592,476
`1/1997 Calamvokis et al.
`370/390
`5,600,650
`2/1997 Oskouy ................................. .. 370/468
`5,602,853
`2/1997 Ben—Michael et al.
`............... .. 370/474
`5,617,416
`4/1997 Damien ................................. .. 370/391
`
`.
`
`
`
`
`
`
`
`I"-"'----"""""""'"'""""""'"'I
`65
`
`|' """ _—""""'
`PACKET
`72
`
`,/68
`
`
`
`INTERFACE
`
`BUS OR
`NETWORK
`
`B
`
`FUNCTIONS)
`
`
`
`XDSL
`INTERFACE
`
`SAR (ATM
`
`ATM
`
`78
`
`
`
`I
`'\7o
`
`i)
`
`CONTROL
`I._-__.._.._...__....___....._-_____-__-___.J
`
`CSCO-1009
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`Cisco V. TQ Delta
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`Page 1 of 8
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`

`
`Jul. 4, 2000
`
`Sheet 1 of 2
`
`6,084,881
`
`NETWORK I
`ACCESS
`PROVI D)ER
`(NAP
`
`XDSL
`INTERFACE
`
`ATM AND
`HIGHER
`
`XDSL INTERFACE
`
`DLL
`
`SERVICE
`
`N ETWORK
`
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`

`
`Jul. 4, 2000
`
`Sheet 2 of 2
`
`6,084,881
`
`BUS OR
`NETWORK
`
`SAR (ATM
`FUNCTIONS)
`
`ACCESS NODE
`
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`
`1
`MULTIPLE MODE XDSL INTERFACE
`TECI-INICAL FIELD OF THE INVENTION
`
`This invention relates in general to digital subscriber line
`communications, and more particularly to a multiple mode
`digital subscriber line (XDSL) interface.
`BACKGROUND OF THE INVENTION
`
`Digital subscriber lir1e (DSL) technology provides a
`physical
`layer protocol
`for communicating information
`across a twisted pair telephone line at data rates exceeding
`those achievable using other physical layer protocols. ()ne
`form of DSL is asymmetric digital subscriber line (i/\|)Sl.)
`communication. ADSL communication involves transmit-
`ting data in one direction (typically towards the customer
`premises) at a greater data rate than data is transmitted in the 7
`other direction (typically towards the local exchange). There
`are also other fonns of DSL such as symmetric DSL (SDSL),
`high-speed DSL (HDSL) and very high-speed DSL (VDSL).
`These various fonns of DSL can be referred to generally as
`XDSL.
`XDSL communication systems are generally implemented
`using a digital subscriber loop access multiplexer (DSLAM)
`located at a central office or other local exchange termination
`point of the public switched telephone network (PSTN). A
`DSLAM typically contains a number of XDSI. termination
`units, or modems,
`that can establish an xDSL link and
`communicate XDSL protocol data across twisted pair tele-
`phone lines. The xDSL termination units car1 be connected
`to the telephone lines via splitter devices that separate the
`xDSL data traffic from voice tra ic on the telephone lines.
`A splitter is similarly used at he customer premises to
`separate voice and xDSL data traffic and to provide the
`xDSL data traffic to an XDSL termination unit located at the
`remote customer premises. Once established, the XDSL link
`allows high speed data communication between the local
`exchange and the customer premises.
`In general,
`the term “customer premises equipment”
`(CPE) can be used to encompass the equipment located at a
`remote customer site in the communication system. The
`CPE typically includes an XDSL interface component that
`has an XDSL tennination unit for terminating the XDSL link
`as well as an interface component between the XDSL ter-
`mination unit and other (TPE components. The XDSI. inter-
`face can comprise, for example, a network interface card
`(NIC) that interfaces between the XDSL link and a bus on a
`personal computer, workstation or other computing device.
`The xDSI_ interface can also form a component of a network
`router or bridge, such as an Ethernet router or bridge.
`There is some disagreement as to what type of data traflc
`should be carried on the XDSL physical layer. For examp e,
`the ADSL Forum has published two technical reports sug-
`gesting competing modes for communicating data traflc
`across the ADSL physical layer. One mode is an asynchro-
`nous transfer mode (ATM) in which data tra Tc is carried by
`ATM cells. The other mode is a packet mode in which data
`is carried using high-level data link control (IIDLC) or
`similar framed data packets. In particular, the framed pack-
`ets can include point-to-point protocol (PPP) in HDLC-like
`frames and frame user network interface (FUNI) frames.
`Because of the competing ATM and packet modes of opera-
`tion for data trallic over the ADSL link, it is possible that
`DSLAMs implemented in different regions will use different
`modes. Consequently, ADSL interfaces designed to be com-
`patible with the ATM mode of operation would not work in
`a packet mode region, and vice versa. Further, one of the two
`modes is likely to become dominant, but it is unclear which
`that will be.
`
`6,084,881
`
`2
`SUMMARY OF THE INVENTION
`
`In accordance with the present invention, a multiple mode
`XDSL interface is provided that provides advantages over
`prior XDSL interfaces.
`In accordance with one aspect of the present invention, a
`multiple mode XDSL interface is disclosed. The multiple
`mode XDSL interface includes an XDSL termination unit
`operable to couple to an xDSL link and to manage commu-
`nication of data across an XDSL physical layer. The multiple
`mode XDSL interface also includes a customer premises
`equipment (CPE) termination unit coupled to the xDSL
`termination unit and operable to couple to customer pre-
`mises equipment. The CPE termination unit has an operating
`mode selected from a plurality of operating modes where
`' each operating mode is associated with a data protocol and
`supports communication of data across the XDSL physical
`layer using the associated data protocol.
`In accordance with another aspect of the present
`invention, a method is disclosed for providing a multiple
`mode interface to an XDSL link. (Communication of data
`across an xDSL physical layer of the XDSL link is managed.
`Aplurality of operating modes are provided where each is
`associated with a data protocol and supports communication
`of data across the XDSL physical layer using the associated
`data protocol. A selection is made between the plurality of
`operating modes, and data is communicated with customer
`premises equipment. Thus, multiple data protocols for com-
`municating across the XDSL physical layer are supported.
`A technical advantage of the present invention is the
`provision of an XDSL interface that supports multiple data
`protocols. For example, the XDSL interface can support both
`an ATM mode and a packet mode of operation. In this
`manner, the XDSL interface allows compatibility with com-
`_ peting protocols for data trallic across the XDSL link. The
`selection between modes for thc XDSL interface can be
`made in hardware or software and can be a manual or
`automatic process. The multiple mode x|)Sl . interface of the
`present invention allows customer premises equipment to be
`built and installed that will support the type of DSLAM that
`is implemented in a particular region.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`8
`
`A more complete understanding of the present invention
`and advantages thereof may be acquired by referring to the
`following description taken in conjunction with the accom-
`panying drawings, in which like reference numbers indicate
`like features, and wherein:
`FIG. 1 is a block diagram of one embodiment of an XDSL
`link interconnecting a remote customer premises and a
`network access provider;
`FIG. 2 is a block diagram of one embodiment of an XDSI.
`communication system using an ATM mode for data traffic
`across an ADSL link;
`FIG. 3 is a block diagram of one embodiment of an XDSL
`communication system using a packet mode for data traffic
`across an ADSL link;
`FIG. 4 is a block diagram of one embodiment of a
`multiple mode xDSI_ interface constructed according to the
`teachings of the present invention; and
`FIG. 5 is a protocol layer diagram relating to the XDSL
`interface of FIG. 4.
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`FIG. 1 is a block diagram of one embodiment of an XDSL
`link interconnecting a remote customer premises and a
`
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`6,084,881
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`i
`
`3
`network access provider. As shown, customer premises
`equipment (CPE) 12 located at tl1e remote site is connected
`to a network access provider (NAP) 14 via xDSI_ link 16.
`Network access provider 14 is in communication with a
`network service provider (NSP) 16 via a wide area network
`(WAN) 18. Further, network service provider 16 provides
`access to an NSP network 20, as shown. XDSL link 16 can
`be an ADSL, SDSL, HDSL, VDSL or other DSL link, and,
`as used herein, xDSL refers generally to these forms of DSL.
`Network access provider 14 represents an entity that
`terminates XDSL li11k 16 at a central office or other local
`exchange termination point. Network service provider 16
`represents an entity that provides access to higher level
`network services. For example, network service provider 16
`can comprise an Internet service provider (ISP) or a corpo— '
`rate office providing network services to a remote 0 ice or
`telecommuter. It should be understood that network access
`provider 14 and network service provider 16 can comprise
`the same physical organization but need not do so. For
`example, a regional Bell operating company (RBOC) could
`provide both xDSL service and Internet access ir1 wl1icl1 case
`it would maintain the role of both network access provider
`14 and network service provider 16.
`Customer premises equipment 12 can comprise a personal
`computer, computer workstation or other computing device
`with an XDSL interface. Alternatively, customer premises
`equipment 12 can comprise a network router or bridge, such
`as an Ethernet router or bridge,
`that
`includes an XDSL
`interface and provides connectivity to a customer premises
`network.
`
`FIG. 2 is a block diagram of one embodiment of an XDSL
`communication system using an ATM mode for data traffic
`across an XDSL link. As shown, a network access provider
`operates an access node 22 which is connected to an x|)SI.
`interface 24 component of the customer premises equip-
`ment. Access node 22 includes an ATM layer function block
`26 that is coupled to an ATM network 28. Access node 22
`further includes a plurality of transmission convergence
`(TC) units 30. Each TC unit 30 is connected to an xDSL
`termination unit (XTU) 32. xDSL termination units 32 in
`access node 22 are designated as “xTU—C” because they are
`associated with the central office or other local exchange
`termination point.
`The customer premises equipment includes XDSL inter-
`face 24 which comprises an XDSL termination unit (XTU)
`34. XDSL termination unit 34 is designated as “xTU-R”
`because it is associated with a remote site. XDSL termination
`unit 34 is in communication with one of the xDSL termi-
`nation units 32 across an xDSL link 36, as shown. At a given
`poir1t ir1 time, any number of XDSL termination units 32
`from access node 22 can be in communication with remote
`XDSL interface units 34 to support communication to cus-
`tomer premises. xDSL interface 24 further includes a trai1s—
`mission convergence (TC) unit 36 and a block 38 that
`provides ATM and higher level functions. Block 38 provides
`an interface to other components of the customer premises
`equipment. Block 38 can interface, for example, to a bus on
`a personal computer, workstation or other computing device.
`Block 38 can also interface to a user network, such as an
`Ethernet local area network.
`
`In operation, access node 22 performs adaptation between
`the public network and ATM network 28. In the downstream
`direction (i.e., towards the customer premises), access node
`22 may perfonn routing and demultiplexing. In the upstream
`direction (i.e., towards the ATM network), access node 22
`may perform multiplexing and concentration. In operation,
`
`55
`
`60
`
`4
`XDSL interface 24 performs termination of the XDSL physi-
`cal layer and ATM layer. ATM layer function block 26 and
`block 38 perform the upstream and downstream routing of
`cell traflic, for example, on a virtual path identifier and/or a
`virtual channel identifier basis. TC units 30 and TC unit 36
`manage the transmission convergence physical sublayer for
`the ATM traffic. ADSI. termination units 32 and ADSI.
`termination 11nit 34 provide physical layer handling for the
`XDSL traffic at the network and customer premises end. An
`ADSL communication system similar to the system shown
`in FIG. 2, as well as the various functional blocks,
`is
`disclosed and described in “Technical Report, TR-002, ATM
`over ADSL Recommendations,” Mar. 20, 1997, the disclo-
`sure of which is incorporated herein by reference.
`FIG. 3 is a block diagram of one embodiment of an XDSI.
`communication system using a packet mode for data traflic
`across an XDSL link. As shown, an access node 40 associ-
`ated with a network access provider is connected across an
`XDSL link 44 to an XDSL interface 42 associated with a
`customer premises. Access node 40 includes a plurality of
`XDSL termination units (xTU-C) 46. Each xDSL termina-
`tion 11nit 46 can be connected to a respective XDSL interface
`42. Within access node 40, each xDSL termination unit 46
`is connected to a digital link layer block 48. Digital link
`layer block 48 in turn can be connected to a digital broadcast
`or packet network, as shown. At the customer premises side,
`XDSL interface 42 includes an XDSL termination unit (xTU-
`R) 50. xDSL termination unit 50 is coupled to a digital link
`layer block 52 which is in turn coupled to a service module
`54. Service module 54 provides an interface to a bus or
`network for communicating with other components of the
`customer premises equipment.
`In operation, the system of FIG. 3 manages communica-
`tion of framed data packets across xDSL link 44. The system
`can be implemented, for example, to support two operating
`modes: poir1t—to—poir1t protocol (PPP) in high—level data link
`control (HDLC) like frames (RFC1662 mode); and frame
`user network interface (FUNI) frames (i.e., FUNI mode). In
`his scheme, the XDSL physical layer provides a point—to-
`3oint physical layer bitstream upon which either of these
`wo framed packet data fonnats can be carried in the data
`ink layer. An ADSL communication system similar to the
`system shown in FIG. 3, as well as the various functional
`alocks, is disclosed and described in “Framing and Encap-
`sulations Standards for ADSL: Packet Mode,” VVT-004, v.
`3.0, March 1997, Technical Report of the ADSI . Forum, the
`disclosure of which is incorporated herein by reference. One
`eature mentioned as a general attribute in this reference is
`hat one implementation can allow switching between opera-
`ion in the RFC1662 mode and FUNI mode for framed data
`oackets. Further, the reference mentions an auto-detection
`scheme and algorithm for accomplishing this switching
`3etween framed packet operating modes.
`In operation, access node 40 communicates packets with
`he connected digital broadcast packet network. Access node
`40 can alternatively communicate with an ATM wide area
`network
`backbone (not shown) using ATM ii1ter—
`working functions. Digital link layer block 48 processes
`oackets and communicates information with appropriate
`XDSL termination units 46 for communication across an
`x|)SI. link 44. Digital link layer block 48 manages the data
`orotocol layer while XDSL transmission unit 46 manages the
`XDSL physical layer. On the customer premises side, xDSL
`ermination unit 50 manages the x|)SI. physical layer and
`communicates data to digital link layer block 52. Digital link
`ayer block 52 manages communicating packets in the
`raming protocol layer. Digital link layer block 52 commu-
`
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`6,084,881
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`
`5
`nicates information with service module 54 which provides
`an interface to other components of the customer premises
`equipment. This interface can be to a bus of a personal
`computer, workstation or other computing device. Service
`module 54 can also provide ar1 interface to a local area
`network. The system of FIG. 3 thus allows framed packets
`to be communicated across the physical layer provided by
`XDSL lir1k 44.
`FIG. 4 is a block diagram of one embodiment of a
`multiple mode xDSL interface constructed according to the
`teachings of the present invention. In particular, the multiple
`mode xDSL interface is advantageous for use in an ADSL
`communication system due to the problem that is presented
`by the competing AI‘M mode and packet mode data protocol
`standards published by the ADSL Forum. Because different
`modes may be used for XDSL links installed in various
`regions, customer premises equipment designed to operate
`in ATM mode would not work in a region with packet mode
`digital subscriber
`line access multiplexers (DSLAMs).
`Conversely, customer premises equipment designed to oper— ,
`ate in packet mode would not work with ATM mode
`DSLAMs.
`According to the present invention, XDSL interface 60 of
`FIG. 4 provides dual modes of operation to be compatible
`with both ATM mode and packet mode data protocols.
`Further, although the embodiment of FIG. 4 is a dual mode
`xDSL interface, additional numbers of modes could be
`supported in accordance with the present invention.
`As shown in FIG. 4, XDSL interface 60 includes an XDSL
`termination unit ('x'l‘U—R) 62 which is coupled to an x|)SI.
`link 64. XDSL termination unit 62 is also coupled to a CPE
`termination unit 65 that provides a multiple mode interface
`to a bus or network at the customer premises. According to
`the teachings of the present invention, CPE termination unit
`65 has multiple modes of operation to handle different
`protocol layers established on XDSL link 64. In the illus-
`trated embodiment, CPE termination unit 65 has two modes:
`ATM mode and packet mode.
`In this dual mode
`embodiment, CPE termination unit 65 includes a switch 66
`that receives a control signal, CONTROL. In the embodi-
`ment of FIG. 4, switch 66 can connect XDSL termination
`unit 62 to one of two paths, as shown, based upon the control
`signal, (T()N'I‘R()I.. The setting of switch 66 can be accom-
`plished in hardware or software either manually or auto-
`matically. In this manner, switch 66 provides a dual path for
`data trallic communicated through XDSL interface 60 of
`FIG. 4. Of course, there are alternative ways to provide
`selectability for CPE termination unit 65 in addition to the
`use of switch 66.
`In the illustrated embodiment, XDSL interface 60 provides
`a packet mode path 68 and an AIM mode path 70. Packet
`mode path 68 can comprise a frame controller 72. Frame
`controller 72 operates to manage framed packet
`communication, such as HDLC or similar framed packets,
`and such functionality is generally available in an integrated
`circuit chip. One example of frame controller 72 is the
`TXC—05101C available from TRANSWITCH CORPORA-
`TION. Frame controller 72 is coupled to a customer pre-
`mises equipment (CPE) interface 74. CPE interface 74 can
`provide an interface to a bus of a personal computer,
`workstation or other computing device. Alternatively, CPE
`interface 74 can provide an interface to a customer premises
`network, such as an Ethernet
`local area network. CPE
`interface 74 operates to communicate data at higher protocol
`layers. CPE interface 74 of FIG. 4 can have selectable packet
`and ATM modes of operation or can comprise separate
`packet and ATM mode paths.
`
`V
`
`~
`
`6
`ATM path 70 can comprise a transmission convergence
`(TC) unit 76 coupled to a segmentation and reassembly
`(SAR) unit 78. SAR unit 78 is then coupled to CPE interface
`74. In operation, SAR unit 78 provides ATM functions for
`ATM mode path 70. Both TC unit 76 and SAR unit 78
`functions can be implemented using integrated circuit chips.
`One example of a TC component is the TXC-05150 avail-
`able from TRANSVVITCH CORPORATION. One example
`of an SAR component is the B18230 product available from
`BROOKTREE (now ROCKWELL).
`According to the teachings of the present invention, XDSL
`interface 60 can be implemented in a network interface card
`(NIC), a network router or bridge, or other customer pre-
`mises equipment. XDSL interface 60 can be implemented as
`a printed circuit board or boards containing a plurality of
`separate integrated circuit chip components to implement
`each of the various blocks. Alternatively, ADSL interface 60
`can include integrated circuit chips that combine two or
`more of the disclosed blocks, such as an application specific
`integrated circuit (ASIC). For example, switch 66, frame
`controller 72, TC ur1it 76, SAR ur1it 78 and CPE interface 74
`can be implemented as one integrated circuit chip. This chip
`can then be coupled to a commercially available chip set for
`XDSL transmission unit 62 available from various XDSL
`suppliers.
`It should be understood that xDSL interface 60 can be
`installed, for example, on a PCI bus or other bus of a
`personal computer, workstation or computing device.
`Further, XDSL interface 60 can form a component of a router
`or bridge for connection to a customer premises network.
`Other uses for x|)Sl. interface 60 are also possible and
`should be apparent to one of skill in the art.
`For the embodiment of FIG. 4, the function of controlling
`CPE termination unit 65 through switch 66 and CPE inter-
`face 74 to select the appropriate path for data traffic can be
`implemented in a number of ways. XDSL interface 60 can
`have a hardware switch, such as a DIP switch, that allows a
`user to hard set the path when XDSI. interface 60 is installed.
`This assumes that the user would know to which mode of
`XDSL link 64 he was connected. For example, the user could
`thus set switch 66 to use either packet mode path 68 or ATM
`mode path 70 upon installation.
`Alternatively, switch 66 and CPE interface 74 can be
`_ controlled by software drivers used to install XDSL interface
`60 and to set up the XDSL stack. The software drivers car1
`be executed by the user when installing XDSL interface 60.
`One of the steps in the setup process can be to set whether
`the xDSL interface 60 will be used in packet mode or ATM
`mode. When the setting is selected,
`that
`information is
`communicated through CPE interface 74 to switch 66.
`Switch 66 is then set to a particular operating mode until
`changed by the user using the software driver.
`A further alternative is to perform mode autodetection
`based upon data being communicated through XDSL inter-
`face 60. The auto-detect process can be performed by CPE
`interface 74 or software executing on other CPI: compo-
`nents. In response to auto-detection of which mode is being
`used, CPE interface 74 or the software could set switch 66
`ir1 the proper mode. For example, switch 66 could be set to
`initially operate in one of the two modes. The a11to-detect
`process could then determine whether or not data is being
`correctly communicated. If not, the process could switch to
`the other mode.
`
`FIG. 5 is a protocol layer diagram relating to XDSL
`interface 60 of FIG. 4. As shown, the XDSL communication
`environment includes an access node, indicated generally at
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`80, and customer premises equipment, indicated generally at
`82, interconnected by an XDSL link, indicated generally at
`84. The protocol layers in access node 80 depend upon
`whether access node 80 uses an ATM mode or packet mode.
`In ATM mode, the protocol layers comprise ATM layer 86,
`transmission convergence (TC) layer 88 and physical media
`dependent (PMD) layer 90. It should be understood that
`additional layers exist above ATM layer 86. However, those
`layers are not discussed herein. In packet mode, the protocol
`layers include frame layer 92 and PMI) layer 94. The access
`node 80 installed in a particular region, for example, may
`use either ATM mode or packet mode. However, it would
`also be possible for an access node 80 to implement both
`ATM and packet modes and allow switching between the
`two modes.
`the dual mode XDSL
`On the customer premises side,
`interface of FIG. 4 supports the illustrated protocol layers. A
`PMD layer 96 is supported by the XDSL termination unit
`whether the XDSL interface is in ATM mode or packet mode.
`However, the layers above PMD layer 96 are dependent
`upon the operating mode of the xDSL interface. If the XDSL
`interface is in ATM mode, then a transmission convergence
`(TC) layer 98 and an ATM layer 100 are supported by the
`xDSL interface. Alternatively, when in packet mode, the
`xDSL interface supports frame layer 102 for handling the
`framed packet communication. It should be understood that
`additional layers exist above ATM layer 100 and frame layer
`102, but are not discussed herein. Communication between
`access node 80 and CPE 82 is thus accomplished across the
`illustrated physical and lower level data protocol layers.
`According to the present invention, the XDSL interface
`component of CPE 82 supports multiple protocol stacks to
`allow a single XDSI. interface to he compatible with multiple
`data protocols. This multiple mode operation provides sig-
`nificant advantages over conventional XDSL interface equip-
`ment.
`
`Although the present invention has been described in
`detail, it should be understood that various changes, substi-
`tutions and alterations can be made hereto without departing
`from the spirit and scope of the invention as defined by the
`appended claims.
`What is claimed is:
`1. A multiple mode digital subscriber line (XDSL)
`interface, comprising:
`an XDSL termination unit operable to couple to an XDSL
`link and to manage communication of data across an
`xDSI_ physical layer; and
`a customer premises equipment (CPE) termination unit
`comprising:
`a packet communication path operable to manage com-
`munication of framed data packets of a data link
`protocol layer;
`an asynchronous transfer mode (ATM) communication
`path operable to manage a transmission convergence
`(TC) physical sublayer and communication of cells
`of an ATM protocol layer;
`a switch coupled to the xDSL termination unit, to the
`packet communication path, and to the ATM com-
`munication path, the switch operable to connect the
`XDSL termination unit to the packet communication
`path or to the /\TM communication path; and
`customer premises equipment
`(CPE)
`interface
`coupled to the packet communication path and to the
`ATM communication path and operable to couple to
`customer premises equipment,
`the CPE interface
`operable to communicate data at higher protocol
`layers;
`
`/
`
`'
`
`8
`such that the multiple mode XDSL interface provides a
`packet operating mode and an ATM operating mode
`for interconnecting to the XDSL link, each operating
`mode associated with a data protocol and supporting
`communication of data across the xDSL physical
`layer using the associated data protocol.
`2. The multiple mode XDSI. interface o claim 1, wherein
`the form of xDSL is asymmetric DSL (ADSL).
`3. The multiple mode x|)Sl .interface o ‘claim 1, wherein
`the CPE interface has selectable packet and ATM operating
`modes.
`4. The multiple mode xT)SI.interface o claim 1, wherein
`the CPE interface comprises separate packet mode and ATM
`mode paths.
`5. The multiple mode XDSL interface 0 claim 1, wherein
`the connection of the switch and the mode of operation of
`the CPE interface are set in hardware.
`6. The multiple mode XDSL interface 0 claim 1, wherein
`the mode of operation of the CPE interface is set by software
`executed on customer premises equipmen , and wherein the
`connection of the switch is set by a control signal from the
`CPE interface.
`7. The multiple mode xDSL interface 0 claim 1, wherein
`the packet communication path comprises a frame controller
`coupled to the switch and to the CPE interface.
`8. The multiple mode xDSL interface 0 claim 1, wherein
`the ATM communication path comprises:
`a transmission convergence (TC) unit coupled to the
`switch; and
`a segmentation and reassembly (SAR) unit coupled to the
`TC unit and to the CPE interface.
`9. The multiple mode XDSL interface of claim 1, wherein
`the framed data packets are high level data link control
`(HDLC) like framed data packets.
`interface of claim 9,
`10. The multiple mode x|)Sl.
`wherein the framed data packets comprise point-to-point
`protocol (PPP) HDLC frames.
`11. The multiple mode x|)Sl _ interface of claim 9, wherein
`the HDLC framed data packets comprise frame user network
`interface (FUNI) frames.
`12. The multiple mode XDSL interface of claim 1,
`wherein the CPE interface is operable to couple to a bus of
`a computing device.
`13. The multiple mode XDSL interface of claim 1,
`_ wherein the CPE interface is operable to couple to a network
`device.
`14. The multiple mode XDSL interface of claim 1,
`wherein the CPE termination unit is implemented as a single
`integrated circuit device.
`15. The multiple mode XDSL interface of claim 1,
`wherein the xDSL termination unit, switch, packet commu-
`nication path, ATM communication path, and CPE interface
`are implemented using separate integrated circuit devices.
`16. The multiple mode xDSL interface of claim 1,
`wherein the switch, packet commtmication path, ATM com-
`munication path, and CPE interface are implemented as a
`single integrated circuit device.
`17. Amethod for providing a multiple mode interface to
`a digital subscriber line (xDSL) link, comprising:
`managing communication of data across an xDSL physi-
`cal layer of the xDSL link;
`providing a physical packet communication path for man-
`aging communication of framed data packets of a data
`link protocol layer and a physical asynchronous trans-
`fer mode (ATM) communication path for managing a
`transmission convergence (TC) physical sublayer and
`communication of cells of an ATM protocol layer in a
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`customer premises equipment (CPE) termination unit,
`such that multiple operating modes are supported, each
`operating mode supporting communication of data
`across the XDSL physical layer using the associated
`data protocol;
`selecting between the packet communication path and the
`ATM communication path using a switch thereby
`changing the operating modes; and
`communicating data with customer premises equipment.
`18. The method of claim 17, wherein selecting an oper-
`ating mode comprises selecting between the packet com-
`m