Local area network

• US 4,847,834 A
• Filed: 01/07/1988
• Issued: 07/11/1989
• Est. Priority Date: 11/14/1984
• Status: Expired due to Fees

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Bryant, Stewart F.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Marcelo, Melvin
• Application Number:
  US07/143,211
• Time in Patent Office: 551 Days
• Field of Search: 364/717, 370/85, 370/89, 370/90, 370/94, 370/95, 370/92, 340/825.06, 340/825.07, 340/825.52
• US Class Current: 370/449
• CPC Class Codes: H04L 12/40013 Details regarding a bus controller
• CPC Class Codes: H04L 12/40169 Flexible bus arrangements arrangements for maintenance or administration involving management of faults; events, alarms H04L41/06; automatic restoration of network faults H04L41/0654
• CPC Class Codes: H04L 12/403 with centralised control, e.g. polling
• CPC Class Codes: H04L 61/5038 for local use, e.g. in LAN or USB networks, or in a controller area network [CAN]
• CPC Class Codes: H04L 61/5092 by self-assignment, e.g. picking addresses at random and testing if they are already in use

Abstract

A local area network including a controller connected to a transmission medium. A plurality of terminals are connected to the transmission medium to initiate a request for an address. Each of the terminals includes a means for locally generating and storing a random number. The random number is transmitted with an address request to the controller. The controller will assign an address to the requesting terminal and append to the assigned address the received random number. When the terminal receives the assigned address and determines that the appended random number is the same as that locally generated, the address is identified as the address of the requested terminal.

Claims

1. A local network comprising:

a controller connected to a transmission medium, said controller assigning an address to a terminal connected to said transmission medium in response to a received address request accompanied by a random number over said transmission medium, and transmitting said assigned address with said random number over said transmission medium;

a plurality of terminals connected to said transmission medium, each of said terminals including;

means for locally generating and storing a random number to be transmitted with an address request over said medium each time a specific interactive operation is performed by a human at said terminal, whereby the likelihood of generating the same random number at different terminals is reduced;

means for transmitting an address request with said locally stored random number over said transmission medium;

means for receiving from said controller over said transmission medium a random number appended to an assigned address; and

means for comparing said received random number with said stored locally generated random number, whereby said appended address is identified as to whether it is the address assigned to a requesting terminal; and

means comprised in said controller for interrogating each terminal at regular intervals to log the address and random number of each terminal.

3. A local area network as claimed in claim 1 or 2, wherein at least one of said terminals comprises a telephone set and the means for generating a random number generates a new random number each time a telephone call is initiated on such telephone set under human control.

4. A local area network as claimed in claim 1 or 2 wherein at least one of said terminals comprises a data set, and the means for generating a random number generates a new random number each time an operator logs on and/or off said data set.

5. A local area network as claimed in claim 1 or 2, wherein the means for generating a random number operates continuously and its output is read into a store each time said specific interactive operation is performed by a human at said terminal, whereby the store contains the new random number then generated.

6. A local area network as claimed in claim 5, wherein the means for generating the random number comprises a continuously cycling counter or pseudo-random sequence generator.

7. A local area network as claimed in claims 1 or 2 in which the means for generating a random number comprises a counter driven by a clock generator, the counter outputs being connected to preset inputs of a clocked pseudo-random sequence generator of the feedback shift register type, the preset inputs being activated in response to a human interaction with the terminal.

8. A local area network as claimed in claim 1 or 2, in which each terminal comprises means for generating a new address request each time a new random number is generated.

2. A local area network comprising:

a controller connected to a transmission medium, said controller assigning an address to a terminal connected to said transmission medium in response to a received address request accompanied by a random number over said transmission medium, and transmitting said assigned address with said random number over said transmission medium;

a plurality of terminals connected to said transmission medium, each of said terminals including;

means for locally generating and storing a random number to be transmitted with an address request over said medium each time a specific interactive operation is performed by a human at said terminal, whereby the likelihood of generating the same random number at different terminals is reduced;

means for transmitting an address request with said locally stored random number over said transmission medium;

means for receiving from said controller over said transmission medium a random number appended to an assigned address; and

means for comparing said received random number with said stored locally generated random number, whereby said appended address is identified as to whether it is the address assigned to a requesting terminal; and

means comprised in said controller for reallocating addresses when two terminals are detected as having the same address but different random numbers.