Token ring fault recovery system for automatically restoring network which includes a transmit possible and receive impossible token holding station

• US 5,600,796 A
• Filed: 05/20/1994
• Issued: 02/04/1997
• Est. Priority Date: 05/21/1993
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.), Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.), Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Takao, Noriyuki, Takano, Hidetoshi, Okamura, Naoki
• Primary Examiner(s): AN, MENG AI T
• Application Number:
  US08/247,207
• Time in Patent Office: 991 Days
• Field of Search: 395/800, 395/200, 395/200.11, 395/200.15, 395/181, 395/183.08, 395/184.01, 370/85.4, 370/85.5, 340/825.5, 364/DIG. 1, 364/DIG. 2
• US Class Current: 714/15
• CPC Class Codes: H04L 12/417 with deterministic access, e.g. token passing

Abstract

A communication network is comprised of several stations that constitute a logical ring to transmit and receive information. The logical ring is established and maintained by a token passing process and a solicit process. The token represents the right to transmit information between the stations in the logical ring. The solicit process solicits stations that are not in the logical ring. The stations in the network include at least one particular station. Each of the stations as well as the particular station include soliciting capability for carrying out the solicit process when holding a token. In addition, each station except for the particular station also includes first solicit repeat capability for repeating the solicit process at most a predetermined number of times when no frame arrives from other stations in the network, and the function of moving to an idle state when no frames arrives from other stations after the solicit process is repeated. The particular station further includes second solicit repeat capability for repeating the solicit process when no frame arrives from any station in the network in response to the solicit process executed by the particular station, and token producing capability for producing the token when no other station joins in the logical ring.

Claims

1. A communication network including a plurality of stations which constitute a logical ring to transmit and receive information, the logical ring being a single path and being established and maintained by a token passing process to pass the token, representing the right to transmit information, between the stations in the logical ring and a solicit process to solicit stations which are not in the logical ring, and the stations in the network including at least one particular station,

each of the stations as well as the particular station, comprising:

solicit means for carrying out the solicit process when holding a token;

solicit response means for transmitting a frame to respond to the solicit process carried out by any station in the network; and

token transmit means for transmitting the token to the station having transmitted a frame to respond to the solicit process, when holding the token;

each station except for the particular station further comprising;

first solicit repeat means for repeating the solicit process at most a predetermined number of times when no frame arrives from other stations in the network to respond to the solicit process, when holding the token;

idle state move means for considering that no other stations join in the logical ring when no frame to respond to the solicit process arrives until the solicit process is repeated for the predetermined number of times, and for moving to an idle state to await the arrival of a frame from any station in the network; and

return means for resuming a predetermined operation from the idle state by responding to an effective frame arriving from any station in the network;

the particular station further comprising;

second solicit repeat means for repeating the solicit process when no frame arrives from any station in the network in response to the solicit process executed by the particular station; and

token producing means for producing the token when no other station joins in the logical ring.

2. A communication method for carrying out communication among a plurality of stations joining in a logical ring which is a single path and which is established and maintained by a token passing process to pass the token, representing the right to transmit information, between the stations in the logical ring and a solicit process to solicit stations which are not in the logical ring, the communication method comprising:

a solicit step for letting the solicit process be carried out by a station which is currently holding the token;

a solicit response step for transmitting a frame from another station to the current token-holding station;

a token transmit step for transmitting the token from the current token-holding station to said another station when the current token-holding station receives the frame in response to the solicit process carried out thereby;

a first solicit repeat step for enabling the current token-holding station to repeat the solicit process at most a predetermined number of times when the current token-holding station cannot receive a frame from any station in the network in response to the solicit process carried out by the current token-holding station which is not a particular station;

idle state move step for considering that no other stations join in the logical ring when no frame arrives to respond to the solicit process carried out by the current token-holding station other than the particular station until the solicit process is repeated for the predetermined number of times, and for moving to an idle state to await the arrival of a frame from any station responsive to the solicit process;

a return step for responding to an effective frame arriving from any station in the network and for enabling the station, which is the token holding station but not the particular station, to resume a predetermine operation;

a second solicit repeat step for repeating the solicit process when the particular station is currently holding the token and when no frame arrives from any station in the network in response to the solicit process; and

a token producing step for permitting the particular station to produce the token when no other station joins in the logical ring.