Dual ring fault isolation

• US 5,463,634 A
• Filed: 02/21/1995
• Issued: 10/31/1995
• Est. Priority Date: 12/23/1991
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Smith, Jay L., Walker, Anthony D., Trubey, Bradley S.
• Primary Examiner(s): Beausoliel, Jr., Robert W.
• Assistant Examiner(s): TU, CHRISTINE TRINH LE
• Application Number:
  US08/391,303
• Time in Patent Office: 252 Days
• Field of Search: 371/20.6, 371/20.1, 371/11.1, 371/11.2, 371/68.2, 370/16, 370/16.1, 370/15, 370/13, 370/85.4, 370/85.12, 370/85.15
• US Class Current: 714/717
• CPC Class Codes: H04L 12/437 Ring fault isolation or reconfiguration for SDH/SONET ring networks H04J3/085

Abstract

Stations on a faulty token ring which includes a control adapter are removed one at a time starting with the most down stream station from the control adapter or of a station up stream from the last station is known to be good all of the stations down stream from that station are removed and the one at a time removal starts with the known good station. The control adapter transmits special beacon frames during the station removal process and when the removal of a station results in receipt of the special beacon frame at the control adapter, the control program identifies a fault domain which includes the station whose removal caused the special beacon to be received at the control adapter and the station immediately up stream from that station. The stations in the fault domain are selectively subjected tests and removed from the ring when a failure is detected.

Claims

1. In a unidirectional token ring network having a transmission media, a plurality of multiport reconfigurable access units coupled to the transmission media and a plurality of stations connected to each one of the plurality of multiport reconfigurable access units, a method for diagnosing said unidirectional token ring network to determine faulty components comprising:

configuring at least one of the multiport access units so that the unidirectional token ring is partitioned into a first unidirectional token ring network and an isolated unidirectional token ring network;

said isolated unidirectional token ring network including a communication adapter coupled to a plurality of switch means, a programmed microprocessor coupled to the switch means and the adapter and selected ones of the plurality of stations coupled to selected ones of the plurality of switch means;

transmitting a unique message frame from said adapter to the selected ones of the plurality of stations;

disconnecting, by means of the microprocessor and selected switch means, one station at a time from the isolated unidirectional token ring network beginning with a station immediately upstream from said adapter and terminating disconnection step upon receipt at said adapter said unique message frame;

using the programmed microprocessor and tables internal to said programmed microprocessor to identify a fault domain which includes a last station, called the downstream station, removed before receiving said unique frame at the adapter and a station immediately upstream, called the upstream station, from the downstream station;

disconnecting all stations from the network;

reconnecting the downstream station;

testing the downstream station, if the downstream station fails, disabling the downstream station;

if the downstream station passes disconnecting the downstream station and reconnecting the upstream station;

testing the upstream station, if the upstream station fails, disabling the upstream station;

if the upstream station passes reconnecting both the downstream station and upstream station; and

testing the upstream and downstream stations, if the upstream and downstream stations fails, disable both.

2. A method as set forth in claim 1 in which the unique message frame is modified by the first station which receives the unique message frame.

3. A method as set forth in claim 2 in which the unique message frame is a type 1 beacon frame with a broadcast address and an address recognized indicator bit which is set to a first state by the first station receiving the type 1 beacon frame.

4. A method as set forth in claim 1 in which the station under test has the station under test output connected to the station under test input by operating a station attachment switch for a predetermined time and then reconnect the station under test to the communication adapter;

examining with the programmed microprocessor, signals received from the reconnected station; and

using the programmed microprocessor to disable predetermined signals are received within a predetermined time after reconnection.

5. A method as set forth in claim 1 in which the stations are first individually tested by sending a frame which is modified by the first station to receive the frame;

and

if the frame is modified, the stations are individually tested by disconnecting the station under test from the network, connecting the station output to the station input for a predetermined time period and reconnecting the station and examining by the programmed microprocessor the signals generated and forwarded from the reconnected station to determine if the station is providing invalid signals.

6. A method as set forth in claim 5 in which the frame which is to be modified by the first station to receive said frame, is a beacon reconfiguration BNR frame with a broadcast address and the first station to receive the frame sets an addressed recognized indicator.

7. A method as set forth in claim 5 in which the signals from a reconnected station are examined for invalidity for a predetermined period of time after the station is reconnected.

8. A method as set forth in claim 7 in which a claim token frame if received from a station within the predetermined time period following reconnection of the station the claim token frame is invalid and the station under test is disabled.