Limited automatic repeat request protocol for frame-based communications channels

• US 7,236,494 B2
• Filed: 09/18/2001
• Issued: 06/26/2007
• Est. Priority Date: 05/21/1999
• Status: Expired due to Term

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Mallory, Tracy
• Primary Examiner(s): To; Doris H.
• Assistant Examiner(s): Hyun; Soon D.
• Application Number:
  US09/955,385
• Publication Number:
  US 20020034182A1
• Time in Patent Office: 2,107 Days
• Field of Search: None
• US Class Current: 370/394
• CPC Class Codes: H04L 1/1635 Cumulative acknowledgement, i.e. the acknowledgement message applying to all previous messages
• CPC Class Codes: H04L 1/1664 the supervisory signal being transmitted together with payload signals; piggybacking
• CPC Class Codes: H04L 1/1685 the supervisory signal being transmitted in response to a specific request, e.g. to a polling signal
• CPC Class Codes: H04L 1/1809 Selective-repeat protocols
• CPC Class Codes: H04L 1/1832 Details of sliding window management
• CPC Class Codes: H04L 1/1838 for semi-reliable protocols, e.g. for less sensitive applications such as streaming video buffer level management for video bitstream receiver H04N21/44004
• CPC Class Codes: H04L 1/1841 Resequencing
• CPC Class Codes: H04L 1/1848 Time-out mechanisms
• CPC Class Codes: H04L 1/1858 Transmission or retransmission of more than one copy of acknowledgement message
• CPC Class Codes: H04L 1/1877 for semi-reliable protocols, e.g. for less sensitive applications like streaming video buffer level management for video bitstream control arrangements H04N21/44004
• CPC Class Codes: H04L 2001/0093 Point-to-multipoint
• CPC Class Codes: H04L 2001/125 Arrangements for preventing errors in the return channel
• CPC Class Codes: H04L 47/34 ensuring sequence integrity, e.g. using sequence numbers
• CPC Class Codes: H04L 69/324 in the data link layer [OSI layer 2], e.g. HDLC

Abstract

In a frame-switched network, a sender sends frames to a receiver over a possibly unreliable channel. Sent frames include frame identifiers that can be used for a limited automatic repeat request. Upon receipt of a frame, the receiver determines, from the frame identifier, if frames prior to the received frame were lost in transit. If the receiver determines that it missed a prior frame, the receiver sends the sender a negative acknowledgment (nack) for the missed prior frame or frames. Otherwise, if the receiver receives a frame correctly, it does not acknowledge the frame. The frame identifiers can be a set of sequential integers with frames transmitted in sequential frame order. In some embodiments, when a receiver receives a frame out of order, the receiver buffers the out of order frame in a receiver buffer for a receive buffer period until preceding frames are received or a receive buffer period expires. The sender can send a reminder frame to the receiver to allow the receiver to detect a missed prior frame missing from an end of a frame sequence. The channel between the sender and the receiver can be a bidirectional channel over a telephone wire, a cable, a radio frequency link or a power wire. Multiple logical channels might be set up between a given sender-receiver pair, to allow for traffic of varying priorities.

Claims

1. A method comprising:

generating a frame at a send station in a network;

sending the frame from the send station to a receive station;

determining a period of inactivity that exceeds a threshold during which no further frames are sent from the send station to the receive station;

sending, in response to the determining, a reminder frame to the receive station identifying a last frame transmitted from the send station to the receive station.

2. The method of claim 1 wherein the generating comprises generating a frame at a send station in a network, the generated frame including a sequence number to identify the frame.

3. The method of claim 2, wherein the generating comprises generating a frame at a send station in a network, the generated frame including a sequence number to identify the frame, sequence numbers being assigned to frames per destination or receive station and per priority level.

4. The method of claim 2 and further comprising:

receiving at the send station a negative acknowledgement (NACK) from the receive station indicating that one or more transmitted frames from the send station were not received by the received station; and

re-sending, in response to receiving the NACK, the one or more frames from the send station to the receive station.

5. The method of claim 1 and further comprising:

resetting a reminder timer for the after each time a frame is sent from the send station to the receive station;

wherein the determining comprises determining a period of inactivity based on an expiration of the reminder timer.

6. The method of claim 1 and further comprising:

storing a copy of the frame in a transmit buffer at the send station;

discarding the copy of the frame if a resource constraint at the send station is met.

7. The method of claim 6 wherein the discarding comprises:

discarding the copy of the frame if a maximum time for storing the frame is met.

8. The method of claim 6 wherein the discarding comprises:

discarding the copy of the frame if a maximum number of stored frames is met.

9. The method of claim 1 wherein the determining a period of inactivity comprises determining a period of inactivity that exceeds a threshold during which no further frames are sent from a send station to a MAC address of the receive station.