System and Method for Binding a Virtual Device Driver to a Network Driver Interface

1. Field of the Invention

The present invention relates to the field of establishing communications between a computer system and input/output devices, such as one-way cable modems. Specifically, the present invention provides a method and apparatus for communicating with input/output device drivers.

2. Description of Related Art

Currently, most home personal computers (clients) are connecting with the Internet and other on-line services using the public telephone network. Most often, data is transferred using Transmission Control Protocol/Internet Protocol (TCP/IP) implemented over such protocols as the Point-to-Point Protocol (PPP) or the Serial Line Internet protocol (SLIP). PPP and SLIP allow clients to become part of a TCP/IP network (such as the internet) using the public telephone network and either an analog modem or an Integrated Services Digital Network (ISDN) device. Clients connect to a network by "dialing-up" a Point of Presence (POP), or "headend", server, which then assigns the client an IP address.

The public telephone network has a switched point-to-point architecture and only offers relatively low bandwidth as it was originally designed for analog voice communication. Thus, it does not scale well to the delivery of broadband data such as multimedia. As a result, there are several efforts to create a broadband data delivery infrastructure for client applications. Such an infrastructure, when combined with the increasingly powerful clients that are now available, will enable the delivery of rich multimedia programming to the home.

Broadband data delivery may be accomplished over a variety of different delivery infrastructures. Of these, perhaps the most promising is the infrastructure currently used to deliver cable television. Recent advancements in radio frequency modulation and demodulation technology, along with a large base of cable television subscribers, has made cable television service providers a strong candidate for becoming the preferred provider of broadband services to the home. In the broadband network architecture, a client will be continuously connected to the broadband network and will be in communication with one or more headend servers at all times.

However, as the cable television network was originally intended only for transmitting data from a headend server located at the cable television service provider's site to one or more subscribers/users (i.e., the network was designed for a one-to-many transmission of information), no provision was made for receiving data from the equipment (i.e., clients) located at the users' locations. Thus, the broadband network architecture only provides for the delivery, and not the receipt, of data. Moreover, although certain broadband networks are becoming equipped with the capability of two way communications, in broadband networks without this capability, no data can be sent back from client to the headend.

A solution has been proposed to achieve two-way communication of data using the existing cable television infrastructure. "Downstream data", defined to be data sent from a headend server to a client, is transferred over coaxial cable from the headend server into the home and to the user's client PC, while "upstream data", defined to be data sent from the client to the headend server, is transferred over the public telephone network. The asymmetrical allocation of upstream/downstream bandwidth is acceptable for most applications as the majority of users requires a larger downstream bandwidth compared to the upstream bandwidth (i.e., most users are "data consumers" rather than "data generators").

In operation, downstream data is received by a client using a "one-way" cable modem while upstream data is transmitted by an analog modem or an ISDN device, over the public telephone network, to the headend server via a Plain Old Telephone Service (POTS) server at the headend office. The POTS server forwards any upstream data sent by the client to the headend server for appropriate action (e.g., providing domain name server (DNS) services, simple mail transfer protocol (SMTP) services, gateway or proxy services, etc.). Without the public telephone network, there is no upstream data path as the client cannot transmit any information to the headend server through the cable modem.

The client and the headend server communicate using TCP/IP. Data is transmitted in packets, where packets are defined as a block of data with appropriate transmission data attached in the form of a header and footer to be sent or received over a network. Downstream and upstream data are sent using the Ethernet standard, as defined by the Institute of Electrical and Electronics Engineers (IEEE) 802.3, modulated for transmission over: (1) coaxial cable using the cable modem; or, (2) a telephone line using the analog modem or the ISDN device and PPP or SLIP protocols.

In order for the client to use the cable modem for communication, the cable modem is installed as an Ethernet adapter in the client, and the client is configured as a TCP/IP network machine. All network traffic appears as digital Ethernet data to the client. However, the data received by the cable modem is transmitted over a coaxial cable network using the analog quadrature ampliture modulation with 6 bit encoding (QAM64) techniques. The QAM64 modulated data transmitted by the headend server is demodulated to digital Ethernet data by the radio frequency (R/F) circuitry of the cable modem.

The upstream and downstream data sent and received by the client over the separate devices are to be treated as a single communications session. However, current operating systems do not provide for the necessary control and communication-interfaces needed for both the upstream network device and the downstream network device. Present operating systems are geared towards controlling network devices that provide both upstream and downstream traffic.

Therefore, an architecture needs to be provided for the above-identified situation where a client PC has separate upstream and downstream device such that the operating system of the client PC can interface with the separate devices. It would also be desirable for this architecture to support different upstream and downstream devices based on technologies other than analog modems, digital adapters, and cable modems. For example, the architecture should be usable with satellite receivers as the one-way data device.

In addition, for computer operating systems which do not allow applications to directly interface with device drivers, a solution needs to be provided.

A method for interfacing applications to network driver interface device drivers is provided, including the steps of binding a virtual device driver to a network driver interface; filling in a network driver interface request structure; and, passing the network driver interface request structure to the network driver interface. An apparatus is also provided, having a processor; a memory coupled to the processor, and configured to cause the processor to bind a virtual device driver to a network driver interface; fill in a network driver interface request structure; and, pass the network driver interface request structure to the network driver interface.

FIG. 1 is a block diagram of a computer network with a client and a server configured in accordance with one embodiment of the present invention;

FIG. 2 is a block diagram of a memory system of the client configured in accordance with one embodiment of the present invention;

FIG. 3 is a flow diagram of the operation of the architecture contained in the memory system of the client in the computer network for interfacing with separate upstream and downstream devices in accordance with one embodiment of the present invention.

FIG. 4 is a block diagram illustrating the operation between a transport driver component, an NDIS layer, and a cable modem driver contained in the memory system of the client.

The present invention provides an architecture for interfacing with input/output device drivers. For purposes of explanation, specific embodiments are set forth to provide a thorough understanding of the present invention. However, it will be understood by one skilled in the art, from reading this disclosure, that the invention may be practiced without these details. Further, although the present invention is described with a one-way asymmetric cable modem network, most, if not all, aspects of the invention apply to all networks in general. Moreover, well-known elements, devices, process steps, and the like are not set forth in detail in order to avoid obscuring the present invention.

The proposed system architecture is used for computer systems communicating in networks such as one way cable modem networks that use analog modems or ISDN adapters for upstream transmissions and cable modems for downstream transmissions. The system architecture includes components for different upstream and downstream devices. The target operating systems are Microsoft.RTM. Corporation's Windows 95.RTM. and Windows NT.RTM. operating systems.

The system components used by the cable modem includes a device driver, an application to interface and control the driver, and an animated user interface to reflect the traffic activity and control the service daemon. A transport layer driver is also used to interface with the device driver for operating systems such as Windows 95.RTM., which do not allow applications to directly communicate with device drivers. After the initial configuration and initialization of the cable modem, data would come from the headend server over the coaxial cable in the cable network. The application is also used to interface and control the device driver for the analog modem.

In order to control the R/F circuitry contained in the cable modem, a Cable Services Library (CSL) is used in the cable modem device driver. Various input/output control (IOCTL) entry points into the cable modem driver, provided by data structures such as object attribute identifiers (OID), are also provided which allow the application to interact and set the cable modem driver parameters. The application can communicate with the driver and provide real-time user feed-back with animated icons to reflect traffic activity or can set various hardware parameters using the OID interface. For operating systems such as Windows 95.RTM., the transport layer driver is needed by the application to access the IOCTL entry ports of the cable modem miniport driver. The transport layer driver is implemented as a "VxD" driver, which is a device driver for Windows 95.RTM. that does not need to be associated with a physical device to exist.

FIG. 1 is a block diagram of a system configured in accordance with a preferred embodiment of the present invention. In FIG. 1, headend server 8 has a CPU 10, a memory system 12, a cable modem 14 and an analog modem 44 communicating with each other over bus 18. Headend server 8 provides high-speed data services and can offer access to the internet and proprietary networks through the use of special interfaces (not shown).

Also in FIG. 1 is a client 22 which includes a bus 24 to which a CPU 26, a cable modem 28 and an analog modem 30 are connected. A memory system 32 is also connected to bus 24. Memory system 32 may be solely random access memory or a combination of random access memory and other, non-volatile, data storage units such as read-only memory or magnetic disk media. Memory system 32 has a client daemon 34 stored in it which cooperate with CPU 26 to provide the desired results. Client 22 is coupled to and communicates with headend server 8 through the use of cable 20.

Client 22 is connected and sends data to headend server 8 through the use of analog modem 30 and a telephone line 36. Headend server 8 receives data from client 22 using analog modem 44. As explained below, headend server 8 communicates with client 22 using a communication protocol such as the Transmission Control Protocol/Internet Protocol (TCP/IP). This protocol allows the performance of a large number of functions including packetizing data by attaching a header and footer to a block of data to be transmitted over a network and setting up a two-way connection between headend server 8 and client 22. Thus, both headend server 8 and client 22 are configured as ordinary TCP/IP network machines.

In operation, data packets are assembled by headend server 8 and sent to cable modem 14, which transmits the data packets to client 22 on cable 20. Cable modem 14 includes an Ethernet adapter which supports the Ethernet standard as defined by the Institute of Electrical and Electronics Engineers (IEEE) 802.3. In addition, cable modem 14 is responsible for transmitting Ethernet packets over cable 20. Some packets are intended to be received by all clients while other packets are targeted for one or more specific clients.

It is to be noted that the functions performed by headend server 8 to transmit and receive the data over cable 20 and telephone line 36 can be divided between one or more servers. For example, a separate server can be used only to handle the communication of data over telephone line 36 while leaving headend server 8 to handle only the communication of data over cable 20.

Memory system 32 of client 22 has various software elements stored in it that cooperate with CPU 26 to provide desired results. These software elements, shown in FIG. 2, include an operating system. As detailed below, in one embodiment, the operating system includes a transport stack layer. The transport stack layer includes a TCP/IP layer and a network driver interface layer. In other embodiments, these layers can be added onto the operating system. Layers are logical divisions in a computer system among its hardware and software functional components.

The TCP/IP layer enables client 22 to receive and send data on a TCP/IP network, such as the Internet. The TCP/IP layer surrounds data passed from upper layers in client 22 with header information before sending the data to other layers in the communication subsystem of client 22.

The network driver interface layer provides communication between the transport layer and a network driver (also referred to as a device driver). Examples of network driver interface layers include the Open Data-Link Interface (ODI) layer from Novell.RTM., Incorporated, and the Network Driver Interface Specification (NDIS) layer from Microsoft.RTM. Corporation.

In one embodiment, the operating system is Windows 95.RTM. or Windows NT.RTM. from Microsoft.RTM. Corporation. Both of these operating systems include a transport stack which includes a TCP/IP layer and an NDIS layer. Further information about the NDIS layer is disclosed, for example, in a CD-ROM from Microsoft.RTM. Corporation entitled Microsoft.RTM. Developer's Network Library (1996), incorporated herein by reference, and in Dhawan, Sanjay, Networking Device Drivers, ch. 5, pp. 197-231, Van Noscrand Reinhold (1995), also incorporated herein by reference.

Device drivers that interface with an NDIS layer are referred to as "miniport" drivers. Miniport drivers are positioned between the NDIS layer and devices such as a network controller or an analog modem to provide control and data interfaces to the system. Device drivers are typically suited only for a particular device, although generic device drivers are available for particular categories of devices.

Other software elements stored within client 22 include application programs and, in one embodiment of the present invention, interface software that includes routines to control the function of a cable modem interface unit. The interface software, when used with an NDIS layer, is implemented as a miniport driver.

In the preferred embodiment, cable modem 28 is installed as an internal card which interfaces to bus 24 of client 22. For example, bus 24 can be a bus which conforms to the Peripheral Component Interconnect (PCI) standard and cable modem 28 can be contained on a card which would interface with PCI busses. Similar to cable modem 14, cable modem 28 includes an Ethernet adapter which supports the Ethernet standard as defined by IEEE 802.3. Cable modem 28 is also responsible for transmitting the Ethernet packets from client 22 to headend server 8 over cable 20.

Thus, after the initial configuration and initialization of cable modem 14, downstream data would come to client 22 from headend server 8 over cable 20. However, in order for client 22 to send data back to headend server 8, an upstream connection would need to be initiated with headend server 8. Once the connection is established, the TCP/IP stack contained on client 22 becomes multi-homed (i.e. client 22 would have two IP addresses--one for analog modem 30 and one for cable modem 28), and any data that need to go upstream (i.e. to headend server 8) would go over telephone line 36 while any data that needs to come downstream is still transmitted over cable 20.

FIG. 2 illustrates the content of memory system 32 of client 22 containing a cable connector component 50, a winsock unit 54, a TCP/IP stack 58, a network driver interface specification (NDIS) layer 60, a cable modem driver 62, and an analog modem driver 64. Memory system 32 of client 22 also contains other system software components that are used in the operation of client 22, but are not shown in FIG. 2.

In one embodiment of the present invention, cable connector component 50 is an application program run by client 22 during system initialization to allow client 22 to communicate with cable modem 28 and analog modem 30 through the cable modem driver 62 and analog modem driver 64, respectively. Cable connector component 50 contains a graphical user interface 202, a control and parse engine 204, a RASDial telco component 206, an input/output control (IOCTL) interface 208, and a winsock component 210.

Control and parse engine 204 of cable connector component 50 controls the operations of the other modules of cable connector component 50. For example, control and parse engine 204 controls both the establishment of connectivity and the responding to poll/command messages from headend server 8. Information received from headend server 8 by winsock component 210 is passed on to control and parse engine 204 to be parsed and then used to perform various operations. Control and parse engine 204 connects and disconnect the telephone/ISDN upstream connection using RasDial telco component 206, as described below. Control and parse engine 204 interacts with cable modem driver 62 using IOCTL interface 208. Also, when cable connector component 50 is initially invoked, control and parse engine 204 will access the Registry to obtain default values for the parameters. A complete listing of all parameters required will be defined later.

Graphical user interface 202 provides both the control and the information interface for a user of client 22. In one embodiment, graphical user interface 202 takes the form of an animated Windows 95.RTM. tray icon which rotates to indicate network traffic and displays different colors to indicate the status of the connection between client 22 and headend server 8 over cable 20. Cable modem driver 62 notifies the intermediate transport driver, win95 transport VxD 212, which in turn notifies graphical user interface 202 when certain events occur. As a result, graphical user interface 202 changes its state and reflects the changes in the tray icon by either changing colors or rotating. Control and parse engine 204 communicates with graphical user interface 202 by sending user datagram protocols UDP datagrams across the winsock interface.

RASDial telco component 206 provides the analog telephone/ISDN connection capability by using the Microsoft.RTM. remote access services (RAS) application programming interface (API) to enable control and parse engine 204 to start a RAS connection operation, get information about existing RAS connections, and end a RAS connection. RASDial telco component 206 is used to establish the RAS connection between control and parse engine 204 (a RAS client) and headend server 8 (a RAS server or terminal server). The connection established creates a multi-homed stack effect in TCP/IP stack 58, which allows the stacks to receive data over one interface (cable modem) and transmit over another (analog phone/ISDN). Cable modem driver 62 also has autodialing capability that causes RASDial telco component 206 to set-up a connection every time an upstream data packet is generated by an application when the upstream connection is not present. The autodialing feature is disclosed in a co-pending application by Mannan Mohammed, one of the named inventors, titled Method and Apparatus for Detecting Network Traffic and Initiating a Dial-Up Connection, U.S. patent application Ser. No. 08/829,584, filed on Mar. 31, 1997, and is incorporated by reference herein.

Input/output control (IOCTL) interface 208 provides a direct interface to cable modem driver 62 via DeviceIOControl calls, during which IOCTL interface 208 first opens a connection to cable modem driver 62 using the "CreateFile" API call. The CreateFile API returns a handle (i.e., pointer) that is used in all future interactions. The IOCTL calls use predefined object attribute identifiers (OID's), which are predefined data structures containing command and data information, to pass parameters between control and parse engine 204 cable modem driver 62.

Control and parse engine 204 connects to the standard transport stacks using a standard UDP socket provided by winsock component 210. This socket will bind to a known port, in one embodiment, port #473, and stays in a "listen" state, waiting for any data to be forwarded to the known port. In one embodiment, this socket connection is planned to be used for one-way downstream traffic, and is a mechanism for control and parse engine 204 to receive the control and polling messages from headend server 8. The socket connection should be non-blocking (i.e., control comes back immediately to the application and the application can continue to receive packets while the application is processing other packets), and implement callback routines (i.e., a sub-routine that is executed when an external event occurs), to notify cable connector component 50 of received data.

Winsock unit 54 is used as an interface to TCP/IP stack 58, and provides an application program interface (API) for application programs such as application 50 to access TCP/IP stack 58. Winsock unit 54 also contains a listing of the port numbers that are being used cable connector component 50 and other applications and the sockets which are bound to those port numbers.

As discussed above, TCP/IP stack 58 performs the functions required when communicating with a TCP/IP network such as the Internet. NDIS layer 60 provides the interface between the network protocol and the network driver. In one embodiment of the present invention, when Windows 95.RTM. or Windows NT.RTM. are used as the operating system of client 22, TCP/IP stack 58 and NDIS layer 60 are included with the operating system.

In addition to having separate devices for upstream and downstream data transfers, a client will be said to be "multi-homed" in that the client's upstream device and its downstream device will both have different IP addresses as the upstream device (i.e., the analog modem or ISDN device), will be assigned an IP address in addition to the IP address already assigned to the cable modem. In the multi-homed environment, all upstream data will be sent to the IP address of the upstream device while all downstream data will be received from the IP address of the downstream device.

Before multi-homing of the client's TCP/IP stack takes place, all packets (data frames) being sent by the client will be delivered to the downstream device (i.e., the cable modem) for transmission to the headend server. However, as the cable modem does not support transmission of upstream data, the cable modem cannot transmit the packets, and as a result, the packets are lost. After multi-homing of the client's TCP/IP stack takes place, upstream data will be sent using the upstream device (i.e., the analog modem on ISDN device) while downstream data will still be received over the cable modem.

In order for the client to become multi-homed and capable of sending data back to the headend server, a user either (1) manually "dials-up" (i.e., the user initiates a connection to) the headend server using functions such as those provided by the Remote Access Services (RAS) library provided by Microsoft.RTM. Corporation in its Windows NT.RTM. and Windows 95.RTM. operating systems; or (2) launches an application that causes the system to automatically dial-up the headend server. Once the connection is established, the TCP/IP stack becomes multi-homed and any data that needs to go upstream would go over the public telephone network while any data that needs to come downstream still comes over the coaxial cable.

Analog modem driver 64 is the software controller for analog modem 30 and provides access to the functions provided by analog modem 30. Thus, analog modem driver 64 is used to communicate with analog modem 30, which in turn is used to communicate with analog modem 44 of headend server 8. In one embodiment, analog modem 30 and analog modem 44 are standard modems configured to work with the public switch telephone network. In an alternate embodiment, adapters transmitting signals using digital technologies such as ISDN can be used. It is also to be noted that any network/medium can be used to provide the upstream connection from client 22 to headend server 8, in addition to analog modems or ISDN adapters. Thus, even adapters which use wireless communications technology can also be used.

Cable modem driver 62 is the software controller for cable modem 28 and provides access to the functions provided by cable modem 28. In one embodiment of the present invention, cable modem driver 62 is a NDIS Miniport driver written to the Microsoft.RTM. Corporation's NDIS 3.1 specification that allows drivers to be binary compatible with Windows 95.RTM. as well as Windows NT.RTM.. Cable modem driver 62 contains an object attribute identifier (OID) module 214 and a cable services library (CSL) 218 in addition to a NDIS miniport module 216.

CSL module 218 provides the cable modem specific API's for manipulating the R/F analog hardware components of cable modem 28. CSL module 218 contains routines that perform functions such as setting the upstream/downstream frequency and R/F circuit power levels of cable modem 28. CSL module 218 also provides API's for checking the status of cable modem 28. A list of the API's provided by CSL module 218 is contained in Appendix B As described below, the API's contained in CSL module 218 is accessed by applications through the OID's in OID module 214.

OID module 214 provides an interface for applications to interrogate and set the hardware parameters of cable modem driver 62. Applications will use DeviceIOControl (IOCTL) calls to communicate with cable modem driver 62. The IOCTL calls use OID's to identify all prior art API's, in addition to the custom API's, such as those contained in CSL module 218, which will be required by applications such as cable connector component 50 to manipulate cable modem 28. As described above, OID's are predefined data structures containing command and data information used to call specific routines in cable modem driver 62. For example, the OID to call the function SetDownstreamFrequency() in one embodiment is the value "0xFF010154." Cable modem driver 62 provides support for all OID's needed to interface with cable modem 28. A complete list of OID's is provided in Appendix A.

Cable modem driver 62 and analog modem driver 64 are specific to cable modem 28 and analog modem 30, respectively. They are used to initialize, configure and control cable modem 28 and analog modem 30, respectively, and are loaded at system boot time. In alternate embodiments, the functions of cable modem driver 62 and analog modem driver 64 can be implemented by one module or more than one modules.

RASDial telco component 206 and analog modem driver 64, are used to initiate an upstream connection with headend server 8. RASDial telco component 206 is a daemon application which is resident in memory system 32 and performs the functions necessary to cause analog modem 30 to dial-up headend server 8. In one embodiment, RASDial telco component 206 uses the RASDIAL API library under Windows 95.RTM. to initiate a dial-up connection.

When a packet is received by client 22 using cable modem 28, it is passed on to cable modem driver 62. Cable modem driver 62 in turn transfers the packet onto TCP/IP stack 58. In TCP/IP stack 58, the packet is checked for errors, stripped of its header and footer and passed on to cable connector component 50.

Conversely, where the data is generated by cable connector component 50, the data is sent to analog modem driver 64 for transmission by analog modem 30 to analog modem 44. Thus, cable connector component 50 would generate a packet which would be sent to TCP/IP stack 58, which would place the proper header and footer on the packet before sending it to analog modem driver 64.

It is to be noted that before an upstream path is established, and before TCP/IP stack 58 becomes multi-homed, cable modem driver 62 is sent any upstream packets. In prior art systems, the cable modem would just discard the upstream traffic. However, as disclosed above, cable modem driver 62 contains the capability to initiate the establishment of an upstream connection through the use of cable connector component 50 when cable modem driver 62 receives any upstream packets.

Also, other applications programs can generate the upstream traffic that is sent to TCP/IP stack 58. An example of an application program is an Internet Web browser that is used to view data received from the Internet and initiate requests of data from the Internet. Thus other application programs can also cause cable modem driver 62 to initiate an upstream connection.

FIG. 2 also contains a Win95 transport VxD 212 that is used in operating systems like Windows 95.RTM., where an application cannot directly interact with a device driver (e.g., cable modem driver 62). Win95 transport VxD 212 is a transport level driver that communicates with NDIS layer 60 and allows IOCTL interface 208 of cable connector component 50 to communicate with cable modem driver 62 in operating systems such as Windows 95.RTM.. Win95 transport VxD 212 is not needed in operating systems such as Windows NT.RTM. that allow an application to directly interact with a device driver.

FIG. 3 is a flow diagram of the operation of the architecture contained in memory system 32 of client 22. The operation of cable connector component 50 begins when cable connector component 50 is initiated, either by a user or by the operating system.

In step 302, cable connector component 50 establishes a socket connection in winsock unit 54. In one embodiment, The socket connection will be bound to port number 473 so that all data sent to that port number is forwarded to cable connector component 50. After the socket connection is established, cable connector component 50 enters an idle mode and waits for data to be received on that port.

In step 304, cable modem 28 is initialized to receive data from headend server 8. In one embodiment, headend server 8 constantly broadcasts data and commands to cable modem 28. Thus, cable modem 28 needs to be configured to the correct broadcast frequency whenever client 22 is operational. Cable modem 28 is configured by either the user or the system at the booting of the client 22. When the user configures the system, the user issues a configuration command at graphical user interface 202. This configuration command is translated into an OID and delivered to cable modem driver 62 through IOCTL interface 208 (win95 transport VxD 212 is optionally used for operating systems such as Windows 95.RTM., as discussed above). The initialization command will tune cable modem 28 to a frequency where it can start receiving packets. When cable modem 28 is configured at boot time, the OID will be issued by the system and cable modem driver 62 uses known valid defaults from a non-volatile source such as the Registry of the operating system to tune cable modem 28. In one embodiment, user intervention to configure the system would be required only when the default tuning by cable modem driver 62 fails.

In step 306, after the system is configured, cable connector component 50 is idle until data is received on the port established in step 302. Any data received by the socket is passed to control and parse engine 204. Control and parse engine 204 interprets the information contained in the received packets and takes the appropriate action according to the discussion below.

In step 308, the received data is parsed by the control and parse engine 204 to determine if a command or poll packet is received from either headend server 8 or the user. If a command or poll packet is received, operation will continue with step 310. Otherwise, operation will continue with step 312.

In step 310, a command or poll packet is received by cable connector component 50. Any request to change to the configuration of cable modem 28 (e.g., changing power levels or tuning to different frequency), is responded to by control and parse engine 204. Control and parse engine 204 uses IOCTL interface 208 to communicate with cable modem driver 62 by sending appropriate OID's. If an acknowledgment to the command or poll packet is required to be sent, control and parse engine 204 generates the acknowledgment. If the user issues commands to either query or change the parameters of cable modem driver 62 or cable modem 28, control and parse engine 204 parses the commands and uses IOCTL interface 208 to communicate with cable modem driver 62. Once a reply is returned by cable modem driver 62, cable connector component 50 displays the information back to the user through the use of graphical user interface 202.

In step 312, if control and parse engine 204 determines that the received data does not contain a command or poll packet, then, in one embodiment of the invention, control and parse engine 204 assumes that the received data contains upstream data that is received because the upstream connection and multi-homing have not been configured. Thus, cable connector component 50 will establish an upstream (RAS) connection. To establish a RAS connection, the dial-up phone number of headed server 8 is obtained by control and parse engine 204 from either the Registry, or a dial-up packet that is frequently broadcast by headend server 8 and is received by control and parse engine 204 on the socket connection.

Using the username and password supplied by the user or obtained from the Registry, control and parse engine 204 establishes a RAS connection with headend server 8. After the connection is established, the upstream traffic will be sent out over the RAS connection due to the multi-homed nature of the transport stacks (i.e., TCP/IP stack 58). Downstream traffic is still received by cable modem 28 and is passed up to the transport stacks (i.e., TCP/IP stack 58), using NDIS layer 60.

FIG. 4 is a block diagram illustrating the interaction between Win95 transport VxD 212, NDIS layer 60, and cable modem driver 62. In operation, Win95 transport VxD 212 binds to NDIS layer 60 for communicating with cable modem driver 62. For querying and setting values in cable modem driver 62, Win95 transport VxD 212 fills in an NDIS.sub.-- REQUEST structure and passes the structure in a NdisRequest call to NDIS layer 60. NDIS layer 60 then transfers the NDIS.sub.-- REQUEST structure via a MiniportQueryInformation call to cable modem driver 62, as shown in FIG. 4. Cable modem driver 62 then places an OID for a particular simple network management protocol (SNMP) command in the structure (e.g., an interrupt request packet (IRP), or the NDIS.sub.-- REQUEST structure), for an object in the network interface card (NIC) driver that it wants to query or set. Depending on the substructure of NDIS.sub.-- REQUEST filled in by Win95 transport VxD 212, the MiniportQueryInformation call results either in the querying or setting of the object that corresponds to the OID provided by Win95 transport VxD 212. Then, the MiniportQueryInformation function fills in the related fields of the NDIS.sub.-- REQUEST structure and passes the structure back to the Win95 transport VxD 212, thereby returning an appropriate status code.

For cable connector component 50 to communicate with cable modem driver 62 in Windows 95.RTM., IOCTL interface 208 in cable connector component 50 opens a DeviceIoControl handle to Win95 transport VxD 212 and passes the OIDs that IOCTL interface 208 wants to query from cable modem driver 62 to Win95 transport VxD 212 via IOCTL calls. The IOCLT calls are similar to application programming interface (API), and contains the OID number referenced above and a memory address for a buffer that contains data to be transferred from the application or the driver. Then, as described above, Win95 transport VxD 212 extracts the OID and the memory address from the IOCTL call received from cable connector component 50. Win95 transport VxD 212 then creates an NdisRequest structure that contains the OID and the memory address. Win95 transport VxD 212 then makes a call to cable modem driver 62 using an NdisRequest, which is sent through NDIS layer 60. When information is returned from cable modem driver 62, as described above, Win95 transport VxD 212 passes the information back to cable connector component 50 by storing the data requested at the memory address provided by the IOCTL call of cable connector component 50 and returning an success indicator to cable connector component 50.

The above described process is used for synchronous operations. Specifically, the requests issued by cable connector component 50 should be completed as they are generated and before cable connector component 50 issues another request. However, in another embodiment, the system can function in an asynchronous mode, where requests issued by cable connector component 50 can be filled by cable modem driver 62 in any order. In the asynchronous embodiment, all IOCTL calls contain a handle (i.e., an event pointer) as a parameter in the IOCTL call. This handle is propagated by Win95 transport VxD 212 through the NDIS layer 60 to cable connector component 50. Cable connector component 50 attaches this handle to any returned call for the IOCTL command, which allows cable connector component 50 to associate the returned data with the original IOCTL call. If an IOCTL command does not contain a handle, then that IOCTL command must be performed synchronously by cable modem driver 62 (i.e., no other command can be performed before this IOCTL command completes). The system can operate in a mixed synchronous/asynchronous mode, with the system operating an asynchronous mode until an IOCTL command with a handle is issued.

It is to be noted that the present invention can be used in other systems with separate upstream and downstream devices. For example, the present invention can be used where the downstream device is a satellite modem.

While the present invention has been particularly described with reference to the various figures, it should be understood that the figures are for illustration only and should not be taken as limiting the scope of the invention. Many changes and modifications may be made to the invention, by one having ordinary skill in the art, without departing from the spirit and scope of the invention.