Computer network with devices/paths having redundant links

• US 5,859,959 A
• Filed: 04/29/1996
• Issued: 01/12/1999
• Est. Priority Date: 04/29/1996
• Status: Expired due to Term

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company), Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Albrecht, Alan, Kimball, Karen
• Primary Examiner(s): DeCady, Albert
• Application Number:
  US08/639,605
• Time in Patent Office: 988 Days
• Field of Search: 395/180, 395/181, 395/182.01, 395/182.02, 395/200.68, 395/200.69, 371/68.2, 371/68.1, 371/20.1, 326/9, 326/10, 370/216, 370/227, 370/228
• US Class Current: 714/4.4
• CPC Class Codes: G06F 11/2007 using redundant communication media
• CPC Class Codes: H04L 41/0213 Standardised network management protocols, e.g. simple network management protocol [SNMP]
• CPC Class Codes: H04L 41/0668 by dynamic selection of recovery network elements, e.g. replacement by the most appropriate element after failure
• CPC Class Codes: H04L 43/0817 by checking functioning
• CPC Class Codes: H04L 45/22 Alternate routing
• CPC Class Codes: H04L 45/28 using route fault recovery
• CPC Class Codes: H04L 69/40 for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection management of faults, events, alarms or notifications in data switching networks H04L41/06

Abstract

A dual-connection option allows preservation of network connectivity to a device or path by providing a second, redundant connection which takes over if a first connection fails. One goal is to provide communication with all critical devices at all times. If the ability to communicate with a device is lost because part of the connection to the device or the device itself has been destroyed, recovery from such loss is provided. The invention is preferably embodied in a particular implementation of the proposed Redundant Links standard, and satisfies the requirements of the proposed IEEE 802.12 standard, while adding specific enhancements to the proposed standard, such as storing and/or reporting conditions that lead up to a failure; accommodating minor, temporary disruptions; allowing status inquiries with regard to a redundant link while maintaining a primary connection; and continuing testing the redundant link after an initial verification.

Claims

1. A redundant links monitor for an electronic network, comprising:

a status capture module associated with either of a network device or network connection for taking a failure snapshot of at least one of at least two links to a network device/network connection and for verifying viability of said links, wherein said links include a primary link and a secondary link, said status capture module storing and/or reporting conditions that lead up to a link failure, accommodating minor, temporary disruptions, allowing status inquiries with regard to a redundant link while maintaining a primary connection, and/or detecting link failure due to incompatible network security configuration;

periodic means for actively determining the status of said secondary link; and

means for selecting the most viable link among said primary link and said secondary link.

2. The redundant links monitor of claim 1, wherein said status capture module is adapted to be polled with respect to said failure snapshot.

3. The redundant links monitor of claim 2, wherein said status capture module may be polled with regard to status of a standby link while an active link is maintained;

and wherein said status capture module resides in a repeater environment.

4. The redundant links monitor of claim 1, further comprising:

means for broadcasting said failure snapshot to a network management function.

5. The redundant links monitor of claim 4, said broadcasting means further comprising:

a network protocol stack for generating a network management trap.

6. The redundant links monitor of claim 1, wherein said status capture module includes a tone detector which is operable in a first mode to detect if a standby state is maintained for a secondary link, and is operable in a second mode to detect if a remote device is responding to training tones when maintaining a degraded connection for a secondary link.

7. The redundant links monitor of claim 6, wherein said monitor is adapted to operate in an IEEE 802.12 environment.

8. The redundant link monitor of claim 1, further comprising:

a failure timer for establishing an interval during which a primary link is maintained in the event of minor and/or temporary disruptions to a connection to said primary link.

9. The method of claim 1, further comprising the step of:

establishing an interval during which a primary link is maintained in the event of minor and/or temporary disruptions to a connection to said primary link.

10. The redundant links monitor of claim 1, said means for selecting further comprising:

means for effecting a redundant links state decision based upon one or more viability factors.

15. The method of claim 9, further comprising the step of:

polling a network connection with regard to status of a standby link while an active link is maintained;

wherein said status capture module resides in a repeater environment.

11. A method for monitoring redundant links to an electronic network entity, comprising the steps of:

taking a failure snapshot of at least one of at least two network links and verifying viability of said links with a status capture module associated with either of a network device or network connection, wherein said links include a primary link and a secondary link, said status capture module storing and/or reporting conditions that lead up to a link failure, accommodating minor, temporary disruptions, allowing status inquiries with regard to a redundant link while maintaining a primary connection, and/or detecting link failure due to incompatible network security configuration;

periodically and actively determining the status of said secondary link; and

selecting the most viable link among said primary link and said secondary link.

12. The method of claim 11, further comprising the step of:

polling a network connection with respect to said failure snapshot.

13. The method of claim 11, further comprising the step of:

broadcasting said failure snapshot to a network management function.

14. The method of claim 13, said broadcasting step further comprising the step of:

generating a network management trap.

16. The method of claim 11, further comprising the step of:

providing a tone detector which is operable in a first mode to detect if a standby state is maintained for a secondary link, and is operable in a second mode to detect if a remote device is responding to training tones when maintaining a degraded connection for a secondary link.

17. The method of claim 16, wherein said method is adapted to operate in an IEEE 802.12 environment.

18. The method of claim 11, said selecting step further comprising the step of:

effecting a redundant links state decision based upon one or more viability factors.