| 摘要 |
A method for improving bandwidth utilization in a packet-switched network via real time control of pause frame transmissions. The invention provides a mechanism whereby a pause frame may be effectively negated if, during the transmission of the pause frame, the network conditions necessitating the pause frame are eliminated or abated. In one Ethernet-compliant embodiment of the invention, monitoring circuitry is provided in a network device to ascertain changes in flow control conditions. Following detection of a flow control condition (e.g., a transmit buffer overflow condition), a flow control unit in the network device initiates transmission of a pause frame. Typically, the initial pause time value will be set to a maximum value (e.g., "FFFF"). During or immediately prior to transmission of the pause frame, the monitoring circuitry functions to monitor the state of the flow control unit or flow control enablement signals to determine if the flow control condition remains in effect. If the monitoring circuitry determines that the flow control condition has been negated, the status of the pause frame transmission is then determined. If the pause time value has not been transmitted, the monitoring circuitry causes a reduced pause time value (e.g., "0000") to be transmitted, thereby effectively negating potentially deleterious effects on network bandwidth that might otherwise result from the original pause frame. In an alternate embodiment of the invention, if the monitoring circuitry determines that the flow control condition giving rise to the pause frame has been negated, the frame check sequence/cyclic redundancy check value at the end of the pause frame is invalidated.
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