Patent Number: 6,167,032

Title: System and method for avoiding host transmit underruns in a communication network

Abstract: A system and method to avoid transmit underruns from a host system to a communication network using an adjustable threshold on a frame basis. The host system includes a device driver, host descriptors and host buffer. The host descriptor define the number of blocks of data to be transferred from the host to the network via a Media Access Control (MAC) device. The MAC device includes a processor, a transmit storage device, and a medium independent interface coupled to the network. The MAC device is connected to the host system via a data bus. A host descriptor is generated for each frame of data transferred by the MAC device from the host to the network. The descriptor is generated by the device driver and provides the MAC processor with a block size of data to be transferred and a threshold in each frame indicating the number of blocks of data to be transferred from the host system to the MAC device to avoid an underrun before transmission to the communication network. The MAC processor generates and transmits a "retry" bit to the device driver when a transmit underrun occurs. The device driver modifies the threshold in subsequent frames to avoid transmit underruns by raising or lowering the thresholds according to the number of retries.

Inventors: Allison; Samuel Steven (Fuquay-Varina, NC), Barker; Kenneth James (Cary, NC), Johnson; Steven Howard (Cary, NC), Lee; Joseph Kinman (Raleigh, NC)

Assignee: International Business Machines Corporation

International Classification: H04L 29/10 (20060101); H04L 12/56 (20060101); H04J 003/14 (); H04L 012/28 ()

Expiration Date: 12/26/2017