Token-passing local area network with improved throughput

• US 4,866,706 A
• Filed: 08/27/1987
• Issued: 09/12/1989
• Est. Priority Date: 08/27/1987
• Status: Expired due to Term

• Current Assignee: Standard Microsystems Corporation (Microchip Technology Incorporated)
• Original Assignee: Standard Microsystems Corporation (Microchip Technology Incorporated)
• Inventors: Gilbert, Sheldon, Sarkissian, Haig, Christophersen, James
• Primary Examiner(s): Olms, Douglas W.
• Application Number:
  US07/089,976
• Time in Patent Office: 747 Days
• Field of Search: 370/89, 370/94, 370/85, 370/60, 340/825.5, 340/825.1
• US Class Current: 370/400
• CPC Class Codes: H04L 12/417 with deterministic access, e.g. token passing

Abstract

A controller is disclosed for use in a local area network preferably of the type having a token-passing protocol. The controller modifies the contents of a data packet or message as it moves on the network media, thereby to intercept, modify and redirect the data message to nodes other than the originally addressed node. In accordance with one embodiment of the invention, the controller is associated with a high-information node (e.g., a file server) connected in a network with a plurality of low-information nodes. The controller modifies the token address transmitted with the token packet from the high-information node after a number of data transmissions so that the token rather than being passed to the next node is returned to the high-information node, thereby allowing a plurality of successive data transmissions to be made in succession from the high-information node to one or more of the low-information nodes.

Claims

1. In a local area network including at least one high-data transmission node and a plurality of low-data transmission nodes said high- and low-data transmission nodes being interconnected by a medium, controller means respectively associated with each of said nodes, said nodes and said associated controller means including means for transmitting a packet having an address portion to another one of said nodes and for receiving a packet from another of said nodes, each of aid nodes being identified by a single address unique to that node, an auxiliary circuit operatively connected to said high-data transmission node, said auxiliary circuit including means for modifying the address portion of a packet transmitted by said controller associated with said high-data transmission node to that of said high-data transmission node and to cause at least the address portion of said packet to be returned to the controller associated with said one high-data transmission node.

2. In the local area network of claim 1, in which said packet includes a token, said modifying means including means to modify the address of the token.

3. In the local area network of claim 2, in which said modifying means comprises means for providing a modified data portion and switch means for replacing an original data portion in the packet with said modified data portion.

4. In the local area network of claim 3, in which said switch means comprises a multiplexer, and control means for inhibiting transmission of the said original data portion and enabling transmission of said modified data portion.

5. In the local area network of claim 4, further comprising logic means for determining during which portion of a data packet the transmission of said original data portion is to be inhibited by said multiplexer.

6. In the local area network of claim 1, in which said auxiliary circuit includes means for returning the modified packet to said high-data transmission node a number of times sufficient to complete the transmission of data from said high-data transmission node and then to pass on the packet to the next of said nodes in the network.

7. In the local area network of claim 1, in which said controller means associated with said high-data transmission node includes a first controller having a first address coupled to the network and a second controller having a second address corresponding to the second highest address in the network, said auxiliary circuit being operatively connected intermediate said first controller and said network.