Electrical computers and digital data processing systems: input/ – Input/output data processing – Data transfer specifying
Reexamination Certificate
2000-10-03
2003-11-18
Huynh, Kim (Department: 2182)
Electrical computers and digital data processing systems: input/
Input/output data processing
Data transfer specifying
C710S074000, C370S392000, C370S351000
Reexamination Certificate
active
06651117
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to computer networking, and more particularly to network stack layer interfaces for efficiently communicating data between network stack layers in a computer network environment.
2. Description of the Related Art
The art of networking computers has evolved over the years to bring computer users a rich communication and data sharing experience. To provide users with such a rich communication experience, standard communication protocols have been developed to improve interoperability between network applications. One such standard is the International Organization for Standard's (ISO) layered communication protocol model called the Open Systems Interconnection (OSI) Reference Model, which is the most widely utilized network communication standard in use today.
The OSI Reference Model defines how messages are transmitted between nodes of a computer network. Generally, the OSI Reference Model is used as a guide to encourage interoperability among devices provided by various network equipment manufactures. As shown in
FIG. 1
, the OSI Reference Model
10
includes seven functional layers divided into two groups, host layers
12
and transfer layers
14
.
The host layers
12
are utilized when a particular message is transmitted from the host machine or when a message is destined for that particular host machine. The host layers
12
comprise four network stack layers. These include an application layer
16
, a presentation layer
18
, a session layer
20
, and a transport layer
22
. The application layer
16
is the layer at which communication partners are identified, quality of service is identified, user authentication and privacy are considered, and constraints on data syntax are identified.
Generally part of the operating system, the presentation layer
18
converts incoming and outgoing data from one presentation format to another. For example, newly arrived text in the form of a text stream may be converted into a popup window. The session layer
20
sets up, coordinates, and terminates conversations, exchanges, and dialogs between applications executing at each end node. Finally, the lowest layer of the host layers
12
is the transport layer
22
, which manages end-to-end control and error-checking, ensuring complete data transfer.
The host layers
12
are generally independent of the actual hardware used to form the computer network. However, the transfer layers
14
are not typically independent of the actual hardware used to form the network, and are therefore generally optimized for efficient performance on the particular devices for which they are designed.
The transfer layers
14
are used when any message passes through the host computer, regardless of whether it is intended for that particular host machine or not. Messages destined for another host machine are forwarded to another host, and are not passed up to the host layers
12
.
The transfer layers
14
include a network layer
24
, a data link layer
26
, and a physical layer
28
. The-network layer
24
handles the routing and forwarding of data. Since larger networks typically include different types of MAC standards, the network layer
24
is used to facilitate communication between different types of networks.
The data link layer
26
provides error control and synchronization for the physical layer
28
by providing transmission protocol knowledge and management. Finally, the physical layer
28
conveys the bit stream through the network at the electrical and mechanical level.
For each message sent between the users, there is a flow of data through each of the functional layers mentioned above. When transmitting, data flows down through the layers starting with the application layer
16
. When the message arrives at the receiving computer, data flows up through the layers starting with the physical layer
24
, and ultimately to the end user.
To function properly, communication between the network stack layers must be provided. Hence, data arriving on the physical layer
28
must be provided to the data link layer
26
, and then from the data link layer
26
to the network layer
24
, and so on up through the rest of the network stack layers. Each network stack layer processes the data and passes it on to the next layer.
Conventionally, copying is used to pass processed data from one network stack layer to the next. Specifically, in a conventional network system, data processed by a particular network stack layer is copied to a buffer. The next network stack layer then reads the data from the buffer, processes it, and copies the processed data into another buffer. This process is then repeated for the rest of network stack layers. In other words, the entire data buffer must be copied to a new buffer each time a new network stack layer needs to access it.
However, copying data into buffers each time a network stack layer needs to pass data to another layer is extremely inefficient. Copying data into buffers is a slow process relative to other processes in the computer network. Moreover, buffer copying requires CPU time that could be better used performing other functions. Thus, conventional networking systems that perform buffer copying when passing data between network stack layers are extremely slow.
In view of the forgoing, there is a need for an interface that provides fast and efficient communication between network stack layers. The interface should avoid buffer copying, yet still provide reliable inter-layer communication. In addition, the interface should be essentially standardized, thus allowing similar routines to use the interface.
SUMMARY OF THE INVENTION
Broadly speaking, the present invention fills these needs by providing a network stack layer interface that efficiently facilitates communication between network stack layers. The interface is configured to pass memory address pointers between network stack layers to avoid buffer copying, thus greatly reducing the amount of copying performed during inter-layer communication. In one embodiment, the network stack layer interface includes a header portion defining various characteristics of the network stack layer interface. In addition, a buffer descriptor is included that defines data to be transmitted over the computer network when operating on a transmitting host, or to data that was transmitted over the computer network when operating on a target. The buffer descriptor includes a memory address pointer to the data. In this manner, information is passed between network stack layers via the network stack interface, resulting in fast network data transfer with reduced data copying.
In another embodiment, a method for transmitting data over a computer network via the network stack layer interface is disclosed. The method includes generating a first, second, and third SCSI information descriptor (SID), as described above. The first SID includes a memory address pointer that points to a first memory address of data to be transmitted over the computer network. The memory address pointer is then passed from the first SID to the second SID, and a storage header memory address pointer is further assigned to the second SID. At this point, the storage header memory address pointer and the data memory address pointer are both passed from the second SID to the third SID. The third SID is then assigned a transport header memory address pointer. Finally, a network interface device is afforded access to the third SID and utilizes the third SID to transmit at least a portion of the data over the computer network.
In yet another embodiment, a method for receiving data over a computer network via the network stack layer interface is disclosed. Similar to the transmitting method above, the receiving method includes generating a first, second, and third SCSI information descriptor (SID). In the receiving method, the third SID includes a memory address pointer to a packet buffer that includes data from a received data packet. The memory address pointer is passed from the
Carrier John
Maranon Renato
Tai John
von Stamwitz Paul J.
Wilson Andrew W.
Adaptec, Inc.
Huynh Kim
Martine & Penilla LLP
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