System and method for improving CSMA/CD network performance during collisions
AssigneeSiemens Information and Communications Systems, Inc.
InventorsShmuel Shaffer, William J. Beyda, Harry Yen, Charles Marcus White
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Abstract
A network node 102 capable of detecting how many parties have collided during attempts to transmit on a bus 108. If more than one party has been detected to collide, the node 102 selects a backoff window from a larger randomized group of possible backoff windows than if the node had collided with only one other party. In this way, delays due to multiple parties colliding are minimized.
Claims23
A method for improving access to a transmission medium in a network system, comprising:
- a first node detecting a transmission collision and determining if said transmission collision is with more than one other node;
- and
- said first node selecting a backoff window having a duration of r multiples of a predetermined backoff time, where r is a randomly distributed integer in the range:
- 0≦r≦2k, where k=min (n, 10), and, for each retransmission attempt, where n is a number greater than a retransmission attempt number, responsive to said first node detecting said transmission collision with more than one other node, and where n is a number equal to a retransmission attempt number responsive to said first node detecting that said transmission collision is with one other node.
A network system, comprising:
- a bus;
- a first node coupled to said bus;
- a second node coupled to said bus;
- and
- a third node coupled to said bus, said third node being configured to detect transmission collisions between said third node and one or more of said first and second nodes and identify if a transmission collision is with one or more of said first and second nodes, and wherein said third node is configured to select first backoff windows according to a first method when said third node detects a transmission collision with one or the other of said first and second nodes, and said third node is configured to select second backoff windows according to a second method when said third node detects a transmission collision with both said first and second nodes.
A computer network node in a network having a plurality of nodes coupled to a bus, comprising:
- a detecting unit for detecting a plurality of collisions of data packets at two or more of said plurality of nodes and identifying a number of nodes involved in a collision;
- and
- a control unit operably coupled to said detecting unit for controlling backoff windows when said collision is detected.
A computer network node in a network having a plurality of nodes coupled to a bus, comprising:
- a detecting unit for detecting a plurality of collisions of data packets at two or more of said plurality of nodes and identifying a number of nodes involved in said collision;
- a control unit operably coupled to said detecting unit for controlling backoff windows when a collision is detected, wherein said detecting unit is configured to monitor voltage levels on said bus, a first voltage level indicative of a collision between said computer network node and two or more of said plurality of nodes, a second voltage level indicative of a collision of data packets between said computer network node and one other of said plurality of nodes.
A computer network node in a network having a plurality of nodes coupled to a bus, comprising:
- a detecting unit for detecting a plurality of collisions of data packets at two or more of said plurality of nodes and identifying a number of nodes involved in said collision;
- a control unit operably coupled to said detecting unit for controlling backoff windows when a collision is detected, wherein said detecting unit is configured to monitor pulses on said bus, a first pulse characteristic indicative of a collision of data packets between said computer network node and said at least two others of said plurality of nodes, a second pulse characteristic indicative of a collision of data packets between said computer network node and one other of said plurality of nodes.
A computer network node in a network having a plurality of nodes coupled to a bus, comprising:
- a detecting unit for detecting a plurality of collisions of data packets at two or more of said plurality of nodes and identifying a number of nodes involved in said collision;
- a control unit operably coupled to said detecting unit for controlling backoff windows when a collision is detected, wherein said control unit is configured to select a backoff window having a duration of r multiples of a predetermined backoff time, where r is a randomly distributed integer in the range:
- 0≦r≦2k, where k=min (n,10), and where n is a number equal to a retransmission attempt number, responsive to said computer network node detecting a collision of data packets between said computer network node and said one other of said plurality of nodes.
Dependencies are inferred from the claim text.