Method of sharing information among a plurality of stations in a frame-based communications network

• US 7,406,106 B2
• Filed: 04/04/2001
• Issued: 07/29/2008
• Est. Priority Date: 04/07/2000
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Mallory, Tracy D.
• Primary Examiner(s): Duong; Frank
• Application Number:
  US09/825,708
• Publication Number:
  US 20020057717A1
• Time in Patent Office: 2,673 Days
• Field of Search: None
• US Class Current: 370/522
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0005 applied to payload information
• CPC Class Codes: H04L 1/0006 by adapting the transmission format
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/0061 Error detection codes
• CPC Class Codes: H04L 1/0072 Error control for data other than payload data, e.g. control data
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence
• CPC Class Codes: H04L 1/18 Automatic repetition systems, e.g. Van Duuren systems
• CPC Class Codes: H04L 1/1809 Selective-repeat protocols
• CPC Class Codes: H04L 1/1848 Time-out mechanisms
• 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 1/1883 using multiple timers
• CPC Class Codes: H04L 1/1887 Scheduling and prioritising arrangements
• CPC Class Codes: H04L 1/20 using signal quality detector
• CPC Class Codes: H04L 12/40032 Details regarding a bus interface enhancer
• CPC Class Codes: H04L 12/4013 Management of data rate on the bus systems modifying transmission characteristics according to link quality H04L1/0001
• CPC Class Codes: H04L 12/40136 Nodes adapting their rate to the physical link properties LAN switches H04L49/351
• CPC Class Codes: H04L 12/40156 by using dedicated slots associated with a priority level
• CPC Class Codes: H04L 12/40163 by assigning priority to messages according to a message field
• CPC Class Codes: H04L 12/403 : with centralised control, e.g. polling
• CPC Class Codes: H04L 12/4035 : in which slots of a TDMA packet structure are assigned based on a contention resolution carried out at a master unit TDM/TDMA multiplex systems per se H04J3/1694; hybrid switching systems H04L12/64
• CPC Class Codes: H04L 12/407 : with decentralised control
• CPC Class Codes: H04L 12/413 : with random access, e.g. carrier-sense multiple-access with collision detection [CSMA-CD]
• CPC Class Codes: H04L 12/417 : with deterministic access, e.g. token passing
• 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: H04M 11/00 : Telephonic communication systems specially adapted for combination with other electrical systems
• CPC Class Codes: H04M 11/06 : Simultaneous speech and data transmission, e.g. telegraphic transmission over the same conductors
• CPC Class Codes: Y02D 30/50 : in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

A method of sharing information among a plurality of stations on a communications network, each of the stations being capable of transmitting and receiving frames over the communications network. A group of agreed-upon flags is established, periodic timing is provided in each station that expires after an interval, and a common frame format is defined providing the capability of specifying a current transmit flag set, an old transmit flag set, and a current receive flag set. Each station maintains: a current transmit state set a recent and previous timer expiration set and a current and previous transmit received set. A control frame is generated and transmitted by a transmitting station to all other stations on the communications network each time a flag in a logical union of current transmit flag sets is set and upon the expiration of the timer in the transmitting station.

Claims

1. A method of sharing information among a plurality of stations on a communications network, each of the plurality of stations being capable of transmitting and receiving frames over the communications network between any one station and all other stations, comprising:

establishing a group of agreed-upon flags, each flag of which is configured by a station of the communications network at any given time;

providing periodic timing in each station that expires after an interval, the interval being common among all the stations and being at least long enough to allow every station on the communications network to transmit a plurality of frames;

defining a common frame format providing the capability of specifying a current transmit flag set, an old transmit flag set, and a current receive flag set;

maintaining by each station;

a current transmit state set indicating by the agreed-upon flags the current capabilities and status flags for that station,

a recent timer expiration set indicating by the agreed-upon flags the capabilities and announced status flags for that station as they were at a most recent expiration of the periodic timing,

a previous timer expiration set indicating by the agreed-upon flags the capabilities and status for that station as they were at a penultimate expiration of the periodic timing,

a current transmit received set indicating by the agreed-upon flags a logical union of all copies of the current transmit flag set received in frames from other stations, and

a previous received set indicating by the agreed-upon flags the current transmit received set at the most recent expiration of its timer; and

generating a control frame by a transmitting station wherein;

the current transmit flag set is set to a logical union of the current transmit state set and the recent timer expiration set,

the current receive flag set is set to a logical union of the current transmit received set and the previous received set, and

the old transmit flag set is set to the value of the previous timer expiration set,

the control frame being generated and transmitted by the transmitting station to all other stations on the communications network each time a flag in any of the logical unions is set or cleared and upon the expiration of the timer in the transmitting station.

2. The method of claim 1 further comprising maintaining by each station a current in use set indicating by the agreed-upon flags a logical union of the current transmit state set, the recent timer expiration set, the current transmit received set, and the previous received set, the current in use set being common to all stations, except temporarily during changes in the overall set of shared flags.

3. The method of claim 1, wherein the agreed-upon flags include a flag indicating transmitting station priority.

4. The method of claim 1, wherein the agreed-upon flags include a flag indicating transmitting station configuration.

5. The method of claim 1, wherein the agreed-upon flags are encoded in arrays of bits set to 0 or 1, with logical functions performed as bitwise operations on the arrays.

6. The method of claim 1 wherein the common frame format includes fields for values other than status flags, plus an identifier for a source sending station, the values being filled in by each source sending station and transmitted to all other stations.

7. The method of claim 1, wherein a station, upon receiving a frame containing the current transmit flag set, the old transmit flag set and the current receive flag set,

detects that a flag which is previously set by at least one station is no longer set by any station, and

upon detection of a flag no longer set by any station, a receiving station clears the flag in its current transmit received set and its previous received set.

8. The method of claim 7, wherein detection of a flag no longer set by any station is performed by a set of logical operations upon the values in a received frame.

9. The method of claim 1, further comprising generating and transmitting a second copy of the control frame being generated and transmitted whenever a flag changes in the current transmit flag set.

10. The method of claim 1 wherein the control frame includes status flags determinative of one or more of:

a version of protocol under which the communications network is operating,

optional feature support,

link-layer priority usage, and

network configuration commands.

11. The method of claim 1 wherein stations receiving the control frames make operational decisions based upon the agreed-upon flags without further interaction amongst the stations on the communications network.

12. The method of claim 1 wherein the control frame is transmitted by a station once per minute or upon a change in current status of the station.

13. The method of claim 1 wherein a second copy of a most recent control frame is transmitted by a station at a randomly selected interval after a control frame is sent by the station announcing a status change.

14. The method of claim 1 wherein the control frame is sent at a highest link layer protocol priority.

15. The method of claim 1 wherein the control frame includes an operation code that may be set to either a request operation code or an announcement operation code such that when a station receives the control frame with the request operation code a timer is set and the receiving station sends a control frame with an announcement operation code at the timer expiration.