Failure detection method in a communication channel with several routes

• US 5,737,311 A
• Filed: 01/11/1996
• Issued: 04/07/1998
• Est. Priority Date: 12/11/1995
• Status: Expired due to Term

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Wyld, Brian Christopher
• Primary Examiner(s): TON, DANG T
• Application Number:
  US08/587,864
• Time in Patent Office: 817 Days
• Field of Search: 370/60, 370/60.1, 370/94.1, 370/94.2, 370/94.3, 370/16, 370/13, 370/14, 370/54, 370/58.1, 370/216, 370/225, 370/227, 370/228, 370/389, 370/395, 370/252, 370/242, 370/247, 370/248, 370/249, 370/250, 370/251, 370/253, 370/256, 370/257, 370/408, 340/827, 340/825.01, 379/221, 395/181
• US Class Current: 370/227
• CPC Class Codes: H04L 1/22 using redundant apparatus to increase reliability

Abstract

A method is provided for detecting failure in a communication channel with at least two routes (A, B), through which at least two stations (X, Y) communicate. According to the method, at least one station repeatedly sends simultaneous messages on routes containing a sequence number, and receives messages from other station(s), containing an array of sequence numbers last received by other station(s) on each route. At least one station then detects failure of a route by comparing the sequence numbers of the array of the messages it receives. The method provides for failure detection independently of real time constraints. Also provided is a station for carrying out this method.

Claims

1. A failure detection method for detecting route failure in a communication system in which a plurality of stations can communicate with each other through each of at least two independent routes, wherein at least one station repeatedly sends simultaneous messages containing a sequence number on said independent routes, and receives messages from at least one other station, wherein the messages received from said at least one other station contain an array of sequence numbers last received by said at least one other station on each independent route;

and said at least one station detects failure of an independent route by comparing the sequence numbers in the array contained in the messages it receives.

2. The method according to claim 1, wherein said sequence number sent by said at least one station is incremented by one each time a message is sent, and wherein the comparing step is carried out by comparing each sequence number in the array with a highest of the sequence numbers in the array, a failure being detected when the result of a comparison is higher than a threshold value.

3. The method according to claim 2, wherein a detected failure is ignored when a route that failed is flow-controlled.

4. The method according to claim 1, wherein each station sends messages containing a sequence number proper to that station, and an array of sequence numbers last received from other station(s) on each route.

5. The method according to claim 1, wherein a station sends messages at regular time intervals, independently of the time at which it receives messages.

6. A station for carrying out a failure detection method in a communication system with at least two independent routes, through which at least two stations communicate, wherein at least one station repeatedly sends simultaneous messages containing a sequence number on said independent routes, and receives messages from at least one other station, wherein messages received from said at least one other station contain an array of sequence numbers last received by said at least one other station on each independent route, and wherein said at least one station detects failure of an independent route by comparing the sequence numbers in the array contained in received messages, said station comprising:

means for sending the simultaneous messages on the at least two independent routes and for receiving messages;

means for storing and changing a current value of a sequence number to be incorporated in messages that are sent;

means for storing a current value of the array of sequence numbers last received on each independent route; and

means for comparing the sequence numbers contained in the array in a received message.

7. The station according to claim 6, wherein said sequence number sent by said at least one station is incremented by one each time a message is sent, and wherein the comparing step is carried out by comparing each sequence number in the array with a highest of the sequence numbers in the array, a failure being detected when the result of a comparison is higher than a threshold value.

8. The station according to claim 6, wherein each station sends messages containing a sequence number proper to that station, and an array of sequence numbers last received from said at least one other station on each route.

9. A communication system for performing a route failure detection method, said communication system comprising:

at least two independent communication routes;

a first station and a second station coupled to communicate with each other through each of said at least two independent communication routes, said first station repeatedly sending to said second station simultaneous messages containing a sequence number on both said independent communication routes, and receiving messages from said second station, which messages contain an array of sequence numbers last received by said second station on each of said two independent communication routes; and

comparing means in said first station for detecting failure of at least one of said independent communication routes by comparing the sequence numbers in the array contained in the messages received from said second station.

10. The communication system according to claim 9, wherein said sequence number sent by said first station is incremented by one each time a message is sent, and said comparing means compares each sequence number in the array with a highest of the sequence numbers in the array, a failure being detected when the result of a comparison is higher than a threshold value.