Apparatus for automatic initiation of data transmission
DC CAFCFirst Claim
1. For a system transmitting frames of data across a communications medium;
- an apparatus comprising;
buffer memory for storing data of frames composed by the host computer for transmission on the communications medium;
means, having a host system interface, for transferring data of frames to the buffer memory;
means, coupled with the buffer memory, for monitoring the transferring of data of a frame to the buffer memory to make a threshold determination of an amount of data of the frame transferred to the buffer memory;
means, responsive to the threshold determination of the means for monitoring, for initiating transmission of the frame prior to transfer of all the data of the frame to the buffer memory from the host computer;
transmit logic, responsive to the means for initiating transmission, for retrieving data from the buffer memory and supplying retrieved data for transmission on the communications medium; and
underrun control logic, which detects a condition in which the means for transferring falls behind the transmit logic, and supplies a bad frame signal to the communications medium in response to the underrun condition.
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Abstract
Early initiation of transmission of data in a network interface that includes a dedicated transmit buffer is provided in a system which includes logic for transferring frames of data composed by the host computer into the transmit buffer. The amount of data of a frame which is downloaded by the host to the transmit buffer is monitored to make a threshold determination of an amount of data of the frame resident in the transmit data buffer. The network interface controller includes logic for initiating transmission of the frame when the threshold determination indicates that a sufficient portion of the frame is resident in the transmit buffer, and prior to transfer of all of the data of the frame into the transmit buffer. The monitoring logic includes a threshold store, which is programmable by the host computer for storing a threshold value. Thus, the threshold value may be set by the host system to optimize performance in a given setting.
101 Citations
26 Claims
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1. For a system transmitting frames of data across a communications medium;
- an apparatus comprising;
buffer memory for storing data of frames composed by the host computer for transmission on the communications medium; means, having a host system interface, for transferring data of frames to the buffer memory; means, coupled with the buffer memory, for monitoring the transferring of data of a frame to the buffer memory to make a threshold determination of an amount of data of the frame transferred to the buffer memory; means, responsive to the threshold determination of the means for monitoring, for initiating transmission of the frame prior to transfer of all the data of the frame to the buffer memory from the host computer; transmit logic, responsive to the means for initiating transmission, for retrieving data from the buffer memory and supplying retrieved data for transmission on the communications medium; and underrun control logic, which detects a condition in which the means for transferring falls behind the transmit logic, and supplies a bad frame signal to the communications medium in response to the underrun condition. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
- an apparatus comprising;
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10. An apparatus for controlling communication between a host system and a network transceiver coupled with a network, comprising:
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a buffer memory; host interface means, having an interface to the host system, for transferring data between the host system and the buffer memory; means, coupled with the buffer memory and including a host system alterable threshold store for storing a threshold value, for monitoring the transferring of data of a frame to the buffer memory to make a threshold determination of an amount of data of the frame transferred to the buffer memory; and means, responsive to the threshold determination of the means for monitoring, for initiating transmission of the frame, prior to transfer of all the data of the frame to the buffer memory from the host computer; network interface means, having an interface to the network transceiver and responsive to the means for initiating, for transferring data between the buffer memory and the network transceiver for transmission; and control means, coupled with the network interface means, for posting status information for use by the host system, as feedback for optimizing the threshold value. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. An apparatus for controlling communication between a host system and a network transceiver coupled with a network, comprising:
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a buffer memory, including a transmit descriptor buffer for storing transmit descriptors identifying data in the host system to be transmitted and including immediate data, and a transmit data buffer for buffering data of frames transferred from the host system; host interface means, having an interface to the host system, for transferring transmit descriptors and data of frames between the host system and the buffer memory and including means, responsive to transmit descriptors in the transmit descriptor buffer, for downloading data of frames from the host system to the transmit data buffer; means, coupled with the buffer memory, for monitoring the immediate data in transmit descriptors in the transmit descriptor buffer and the downloading of data of a frame to the transmit data buffer to make a threshold determination of an amount of data of the frame transferred to the buffer memory; and means, responsive to the threshold determination of the means for monitoring, for initiating transmission of the frame, prior to transfer of all the data of the frame to the buffer memory from the host computer; network interface means, having an interface to the network transceiver and responsive to the means for initiating, for transferring data between the buffer memory and the network transceiver for transmission; and underrun control means, coupled with the network interface means, for detecting an underrun condition in which the host interface means in downloading data to the transmit data buffer falls behind the network interface means in transferring data to the transceiver, and for supplying a bad frame signal to the network transceiver in response to the underrun condition. - View Dependent Claims (19, 20)
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21. A network interface adapter for a carrier sense, multiple access network with collision detection (CSMA/CD), comprising:
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buffer memory which stores data of frames composed by a host computer for transmission on the network; data transfer circuitry, having a host system interface, for transferring data of frames to the buffer memory; logic, coupled to the buffer memory, which monitors the transferring of data of a frame to the buffer memory to make a threshold determination of an amount of data of the frame transferred to the buffer memory; a medium access controller for the CSMA/CD network coupled to the buffer memory for managing transmission of frames of data from the buffer memory to the network; and logic, responsive to the threshold determination of the logic which monitors the transferring of data to the buffer memory, which initiates transmission of the frame from the buffer memory to the medium access controller prior to transfer of all of the data of the frame to the buffer memory, including logic which initiates transmission of the frame when no complete frame of data is present in the buffer memory. - View Dependent Claims (22, 23, 24, 25, 26)
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Specification