Method for controlling failover between redundant network interface modules

• US 5,016,244 A
• Filed: 09/08/1989
• Issued: 05/14/1991
• Est. Priority Date: 09/08/1989
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Drobish, Renee, Massey, W. Russell Jr., McLaughlin, Paul F.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): HSU, ALPUS
• Application Number:
  US07/404,748
• Time in Patent Office: 613 Days
• Field of Search: 370/85.4, 370/85.5, 370/85.9, 370/85.13, 370/85.11, 370/85.14, 370/85.15, 370/16, 370/60, 370/60.1, 370/94.1, 370/94.3, 371/8.1, 371/11.1, 340/825.01, 340/827, 340/825.02, 340/825.5, 340/825.51, 340/825.52
• US Class Current: 370/217
• CPC Class Codes: G06F 11/2005 using redundant communication controllers
• CPC Class Codes: G06F 11/2007 using redundant communication media
• 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 method by which redundant network interface modules (NIMs) interconnecting the communication buses of two local area networks communicate with one another at predetermined time intervals over the communication buses of both networks. A first NIM of a redundant pair of NIMs is designated as the primary and a second NIM of the redundant pair is designated as the secondary. Contents of the information communicated between the NIMs over the communication bus of the first network includes the status of the transmitting NIMs ability to communicate with the second network and the information communicated between the NIMs over the communication bus of the second network includes the status of the transmitting NIM'"'"'s ability to communicate with the first network. Based on the information exchanged, the failure of the NIMs to communicate as scheduled, and the internal status of each NIM as understood by that NIM, the NIMs decide when failover from the primary NIM to the secondary NIM occurs.

Claims

1. A method by which redundant network interface modules (NIMs) interconnecting communication buses of a first and second local area network communicate with one another over the communication buses of the first and second local are network whereby each of the redundant NIMs includes a first NIM and a second NIM, the first NIM being designated as the primary and second NIM being designated as the secondary, the secondary NIM taking over the function of the primary NIM on the occurrence of failover conditions;

comprising the steps of;

the first and second NIMs communicating with each other at predetermined time intervals over the communication buses of both networks, each communication between the NIMs over the communication bus of the first network including the status of the second network as perceive by the NIM transmitting the message and each communication between the NIMs over the communication bus of the second network including the status of the first network as perceived by the NIM transmitting the message;

the primary NIM failing over to the secondary NIM when the primary NIM determines that it is unable to communicate with the first network and the secondary NIM determines that it is able to communicate with the first network.

2. The method of claim 1 further comprising the step of the secondary NIM terminating its operation if the secondary NIM is unable to communicate with the first network.

3. The method of claim 2 in which each communication between the NIMs includes current operating status of the NIM originating such a communication, and further comprising the step of the secondary NIM terminating its operation if the secondary NIM detects it has suffered a hardware or a software failure.

4. The method of claim 3 further comprising the step of the primary NIM failing over to the secondary NIM if the primary NIM detects it has suffered a hardware or a software failure.

5. The method of claim 4 in which the primary NIM fails over to the secondary NIM without communicating status information in a status message to the secondary NIM that it has suffered a hardware or a software failure.

6. The method of claim 5 in which each of the predetermined time intervals is one second.

7. The method of claim 6 in which the first local area network is a token passing network.

8. The method of claim 7 in which the second local area network is a token passing network.

9. In a process control system including an universal control network (UCN) and a local control network (LCN), each being a local area network (LAN) with each network including a plurality of modules, the modules of the UCN and the modules of the LCN communicating with one another over a communication bus, a pair of network interface modules other NIM being designated as a secondary, each of the NIMs being connected between the communication buses of the UCN and the LCN and functioning to provide communication and data translation between the UCN and the LCN, the primary NIM providing such function unless replaced by the secondary NIM, and the secondary NIM being available to provide this function instead of the primary NIM upon the occurrence of predetermined failover conditions, a method for providing the communication function comprising the steps of:

(a) the secondary NIM transmitting to the primary NIM at least once during every first period of time over the UCN communication bus a status message, the secondary NIM'"'"'s status message including the current operating status of the secondary NIM and the status of the LCN as determined by the secondary NIM;

(b) the primary NIM transmitting to the secondary NIM at least once during every first period of time over the UCN communication bus a status message, the primary NIM'"'"'s status message including the current operating status of the primary NIM and the status of the LCN as determined by the primary NIM;

(c) the primary NIM transmitting to the secondary NIM at least once during every first period of time over the LCN communication bus a status message, the primary NIM'"'"'s status message including current operating status of the primary NIM, of the UCN as determined by the primary NIM, and updating data with which the secondary NIM updates the secondary NIM'"'"'s data base so that the data base of the secondary NIM substantially matches the that the data base of the secondary NIM substantially matches the data base of the primary NIM;

(d) the secondary NIM transmitting to the primary NIM upon receiving a predetermined number of messages from the primary NIM in step (c) containing updating data or during every first period of time, which ever first occurs, over the LCN communication bus a status message, the secondary NIM'"'"'s status message including the current operating status of the UCN as determined by the secondary NIM;

(e) the primary NIM failing over tot he secondary NIM if the primary NIM is unable to communicate with the LCN, and the secondary NTM is able to communicate with the LCN and status messages containing such data are received by both NIMs;

(f) the secondary NIM terminating its operations if it determines that it is unable to communicate with the LCN;

(g) the primary NIM terminating operation of the secondary NIM if the secondary NIM is unable to communicate with one of the LANs;

(h) the primary NIM terminating communications with the secondary NIM if the secondary NIM crashes; and

(i) the secondary NIM taking over the function of the primary NIM if the primary NIM crashes, if the primary NIM is commanded to shut down by a command from a universal control station module of the first network, or if the primary NIM is powered down.

10. The method of claim 9 in which the first period of time is one second.

11. The method of claim 10 in which the universal control network is a token passing network.

12. The method of claim 11 in which the local control network is a token passing network.