Method of automatic retransmission of frames in a local area network

• US 5,548,796 A
• Filed: 05/04/1994
• Issued: 08/20/1996
• Est. Priority Date: 11/02/1993
• Status: Expired due to Term

• Current Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Original Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Inventors: Ketchum, Kevin D.
• Primary Examiner(s): Harrell, Robert B.
• Assistant Examiner(s): Coulter, Kenneth R.
• Application Number:
  US08/237,822
• Time in Patent Office: 839 Days
• Field of Search: 395/250, 395/200, 395/872
• US Class Current: 710/52
• CPC Class Codes: H04L 47/6215 Individual queue per QOS, rate or priority
• CPC Class Codes: H04L 49/90 Buffering arrangements
• CPC Class Codes: H04L 49/9063 Intermediate storage in different physical parts of a node or terminal
• CPC Class Codes: H04L 49/9084 Reactions to storage capacity overflow

Abstract

A configurable network interface controller that provides for the automatic retransmission of collided Ethernet frames from a local RAM while observing two modes of operation: (1) retransmission of as much of the frame as possible without violating latency requirements and (2) first guaranteeing the safe retransmission of the first 64 bytes and then returning to observation of the latency requirements.

Claims

1. A method of retransmitting a selected number of initial elements of an information frame from a first station in a local area network after a transmission collision occurs between an initial attempt to transmit the information frame from the first station and a simultaneous attempt to transmit an information frame from a second station in the local area network, the second station having transmit priority over the first station;

the method comprising;

providing a storage device having a number Y of storage locations for sequentially storing individual information frame elements;

selecting one of the following retransmission modes;

(i) a low latency mode wherein a storage device threshold location Z is designated in the O-Y sequence of storage locations such that storage locations O-Z may be overwritten with new information elements after the transmission collision, but storage locations (Z+1)-Y may not be overwritten until the first to occur of either successful retransmission of the information elements stored in storage locations (Z+1)-Y or a predefined number of unsuccessful attempts at retransmission of said information elements, where Z may be less than, greater than or equal to X, and

(ii) a high latency mode wherein the storage device threshold location Z=X, and wherein mode (i) is selected following successful retransmission of the information stored in storage locations (X+1)-Y.