Electrical computers and digital processing systems: multicomput – Computer-to-computer session/connection establishing
Reexamination Certificate
1998-06-12
2001-06-05
Harrell, Robert B. (Department: 2152)
Electrical computers and digital processing systems: multicomput
Computer-to-computer session/connection establishing
C709S250000, C709S241000
Reexamination Certificate
active
06243753
ABSTRACT:
BACKGROUND OF THE INVENTION
1. The Field of the Invention
The present invention relates to methods for managing connection-oriented hardware media in an I/O subsystem of a computer operating system. More particularly, the present invention relates to a Raw Data Transport (RDT) that provides a bridging function between an integrating component providing generalized connection management and a data streaming architecture.
2. Present State of the Art
The effectiveness of general purpose stand alone computers, such as the personal computer found in most office environments and laptop computers increasingly used by professionals requiring portability, has been substantially improved by allowing communications between machines over a communications network. Such networking of computers allows the sharing of resources found on one computer with other computers in the network. For example, storage areas having files, printers, modems, and other resources may all be advantageously shared.
Data that is shared between computers can be sent in packets across a physical network connection and read by destination computers. Such packetized network data may be requests for shared resources, data, such as a file, or other information that must be communicated from one computer to the other. As used herein, the term “network data” refers to data or information that is actually transmitted over the communications network between different computers.
The physical network between the different computers can be categorized into two general types. The first type of network makes use of a “connectionless” media wherein the packetized network data contains destination information, such as a network address, and is simply placed on the network by the hardware media (hereinafter referred to simply as “media”) and routed to the destination. A common network interface card that provides access to an Ethernet would be an example of a connectionless media. The destination will recognize the address in the packet and process it accordingly while other destination nodes will simply ignore the packet since it lacks the correct address information.
Another type of physical network utilizes a connection-oriented hardware medium, such as telephone modem, cable modem, or ISDN connector. With connection-oriented media, a connection must be made and maintained in addition to sending and receiving packets of information. The connection-oriented media will send and receive data packets directly with the destination node that has matching hardware and with which a connection has been made. Once data is received, it is treated in the same manner by the I/O subsystem. Connection-oriented media are commonly found for Wide Area Network (WAN) implementations.
On a particular computer or node of the network, a network interface card (NIC) or network card monitors the physical communications channel for packets destined for that computer as well as transmits packets of network data destined for other computers. A connection-oriented NIC will first have to make the connection before packets may be sent and received. Once the connection is made, the connection-oriented NIC may receive and send packets as described above depending on the nature of the connection-oriented media. Software components run on the node computer under direction or control of the operating system or architecture for managing and controlling the network card operations. Furthermore, other software components exist to further abstract the network communications channel and provide more and more general networking interfaces for higher layers using their services. The layered approach allows compartmentalization and easier development of network applications.
One model used to provide a structure for layered software component development is the seven-layer ISO model that is well known in the art. While actual implementations of the ISO model do not necessarily rigidly isolate each particular layer as a separate component exposing its own interface to layers above and below, the concepts of the model are generally applicable. For purposes of this disclosure, the lower layers of the ISO model are most at issue, namely, the data link layer implemented by a network card device driver, and the transport and network layers implemented as a transport protocol driver.
Lower level networking functions, such as are discussed throughout this application with respect to controlling a network card and initial processing of packetized network data, are handled by special system software components called drivers that integrate with a host operating system according to a specific architecture and have special privileges for accessing system resources. Throughout this application, reference will be made to the Windows NT® operating system available from Microsoft Corporation and to its specific architecture wherein lies one embodiment of the present invention. Such drivers run in “kernel mode,” meaning they have higher privileges and access to system resources than do “user mode” application process threads. While specific reference is made to Windows NT concepts and terminology, those skilled in the art will recognize that many, if not most, operating systems share similarities relevant to the environment of the present invention.
Because there are different types of transport protocols developed over time by different entities for different reasons, there may be different types of transport protocol drivers acting as software components running on a single host computer system in order to provide the necessary networking capabilities for a given installation. Some common transport protocols include TCP/IP, IPX, AppleTalk®, and others. Each transport protocol driver will communicate with one or more individual network card device drivers in order to send network data over a communications network and receive incoming packets from the communications network.
Furthermore, because there are a multitude of network cards provided by numerous manufacturers, there are a corresponding large number of potential network card device drivers. In order to support full connectivity to the transport protocol drivers, each network card device driver must support the ability to communicate with each different type of transport protocol driver. Because of the complexity of many different variations that could conceivably be connected together due to the layered component approach, building such drivers can be a time intensive process and the nature of the different interfaces each driver must use is illustrated in FIG.
1
.
FIG. 1
is a block diagram showing the structure of a plurality of network cards, network card device drivers, and transport protocol drivers that each must interact with system resources and a central database or registry having connectivity information in order to operate properly. Furthermore, each transport protocol driver must support each and every network card device driver for which it may be connected and in like manner each network card device driver must support communicating with each and every transport protocol driver to which it may be connected.
If a new transport protocol driver is introduced, each network card device driver wanting to support the new transport protocol driver may require modification to the source code followed by a re-release and distribution of the executable driver code. Likewise, a new network card device driver may also require a similar re-release. Releasing and distributing software is an expensive process that software companies desire to limit as much as possible.
For example, passing network information arriving on network card
20
controlled by network card device driver
22
to the transport protocol driver
24
requires the transport protocol driver
24
and the network card device driver
22
to be fairly complex in terms of programming effort. This may take significant time for a developer or engineer to create. Note that the network card driver
22
must not only interact with the network interface card
20
but al
Hyder Jameel
Machin Richard C.
Harrell Robert B.
Microsoft Corporation
Vu Thong
Workman & Nydegger & Seeley
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