LINE BACKUP METHOD AND SYSTEM

• US 20030137933A1
• Filed: 01/04/1999
• Published: 07/24/2003
• Est. Priority Date: 01/12/1998
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: YAMADA, HIROSHI, KATO, TAKASHI, ETOH, FUMIHARU
• Granted Patent: US 7,266,078 B2
• Time in Patent Office: Days
• US Class Current: 370/225
• CPC Class Codes: H04L 12/5601 Transfer mode dependent, e.g. ATM
• CPC Class Codes: H04L 2012/5627 Fault tolerance and recovery
• CPC Class Codes: H04L 49/255 Control mechanisms for ATM switching fabrics

Abstract

A control PVC is set up on a line connecting between exchange units, and periodic communication is performed between the exchange units using the control PVC. The periodic communication is monitored at each exchange unit for detection of a line failure and, at each exchange unit, a connection on the line is automatically switched over to a reserve connection in the event of a line failure. For manual switchover of a connection set up between the exchange units, a manual switchover request is issued from a maintenance console connected to one of the exchange units and, in response to the request, switchover request information is sent to the other exchange unit. The exchange unit that received the switchover request information switches the connection over to a reserve connection, and returns a switchover completion notification. The exchange unit that received the switchover completion notification switches the connection over to a reserve connection.

Claims

1. A line backup method comprising the steps of:

setting up a permanent virtual connection on a line connecting between a first exchange unit and a second exchange unit;

performing periodic communication between said first exchange unit and said second exchange unit using said permanent virtual connection;

detecting a failure of said line by monitoring said periodic communication at each of said first and second exchange units; and

switching a connection on said line, at each of said first and second exchange units, to a reserve connection not using said line, in the event that a failure of said line is detected.

2. A method according to claim 1, wherein the connection to be switched at each exchange unit includes a terminating connection terminating in said exchange unit as well as a relay connection not terminating in said exchange unit.

3. A method according to claim 1, further comprising the step of analyzing at said second exchange unit the condition of an opposite-end line directed to a third exchange unit when the connection to be switched to a reserve connection at said second exchange unit is a connection to be relayed from said second exchange unit to said third exchange unit along said opposite-end line, and wherein:

in said switching step, the reserve connection to be switched to is determined in accordance with the result of the analysis of said opposite-end line.

4. A method according to claim 1, further comprising the steps of:

sending a switchover request signal to a third exchange unit from each of said first and second exchange units when said reserve connection is a connection to be routed via said third exchange unit;

receiving at said third exchange unit said switchover request signal sent from each of said first and second exchange units;

setting up said reserve connection at said third exchange unit in response to said switchover request signal; and

sending a processing completion notification from said third exchange unit to said first and second exchange units.

5. A method according to claim 1, further comprising the step of prestoring, for said connection, an identifier of said reserve connection.

6. A line backup method in which a connection on a line connecting between a first exchange unit and a second exchange unit is switched over to a reserve connection not using said line, comprising the steps of:

sending switchover request information from said first exchange unit to said second exchange unit in response to a manual switchover request from a maintenance console connected to said first exchange unit;

switching said connection over to said reserve connection at said second exchange unit in response to said switchover request information, and sending a switchover completion notification from said second exchange unit to said first exchange unit; and

switching said connection over to said reserve connection at said first exchange unit in response to said switchover completion notification.

7. A line backup method according to claim 6, further comprising the steps of:

sending switchover request information from said second exchange unit to a third exchange unit when the connection to be switched over to a reserve connection at said second exchange unit that received said switchover request information is a connection to be relayed from said second exchange unit to said third exchange unit; and

switching said connection over to a reserve connection at said third exchange unit in response to said switchover request information, and sending response information from said third exchange unit to said second exchange unit.

8. A method according to claim 6, further comprising the step of prestoring for said connection an identifier of said reserve connection.

9. A line backup system comprising:

a permanent virtual connection set up on a line connecting between a first exchange unit and a second exchange unit;

a periodic communication processing block for performing periodic communication between said first exchange unit and said second exchange unit using said permanent virtual connection;

a line failure detection block for detecting a failure of said line by monitoring said periodic communication at each of said first and second exchange units; and

a switchover processing block for switching a connection on said line, at each of said first and second exchange units, to a reserve connection not using said line, in the event that a failure of said line is detected.

10. A system according to claim 9, wherein the connection to be switched at each exchange unit includes a terminating connection terminating in said exchange unit as well as a relay connection not terminating in said exchange unit.

11. A system according to claim 9, further comprising an opposite-end line condition analyzing block for analyzing at said second exchange unit the condition of an opposite-end line directed to a third exchange unit when the connection to be switched over to a reserve connection at said second exchange unit is a connection to be relayed from said second exchange unit to said third exchange unit along said opposite-end line, and wherein:

said switchover processing block determines the reserve connection to be switched to in accordance with the result of the analysis from said opposite-end line condition analyzing block.

12. A system according to claim 9, further comprising:

an information transmitting block, provided at each of said first and second exchange units, for sending a switchover request signal to a third exchange unit when said reserve connection is a connection to be routed via said third exchange unit;

an information receiving block for receiving at said third exchange unit said switchover request signal sent from each of said first and second exchange units;

a designated connection setup block for setting up said reserve connection at said third exchange unit in response to said switchover request signal; and

a second information transmitting block for sending a processing completion notification from said third exchange unit to said first and second exchange units.

13. A system according to claim 9, further comprising a connection management table in which an identifier of said reserve connection is prestored for said connection.

14. A line backup system in which a connection on a line connecting between a first exchange unit and a second exchange unit is switched over to a reserve connection not using said line, comprising:

an information transmitting block for sending switchover request information from said first exchange unit to said second exchange unit in response to a manual switchover request from a maintenance console connected to said first exchange unit;

a connection switchover processing block for switching said connection over to said reserve connection at said second exchange unit in response to said switchover request information;

a second information transmitting block for sending a switchover completion notification from said second exchange unit to said first exchange unit; and

a second connection switchover processing block for switching said connection over to said reserve connection at said first exchange unit in response to said switchover completion notification.

15. A line backup system according to claim 14, wherein

said second information transmitting block sends switchover request information from said second exchange unit to a third exchange unit when the connection to be switched over to a reserve connection at said second exchange unit that received said switchover request information is a connection to be relayed from said second exchange unit to said third exchange unit, said system further comprising:

a third connection switchover processing block for switching said connection over to a reserve connection at said third exchange unit in response to said switchover request information; and

a third information transmitting block for sending response information from said third exchange unit to said second exchange unit.

16. A system according to claim 14, further comprising a connection management table in which an identifier of said reserve connection is prestored for said connection.