Industrial controller employing the network ring topology

• US 8,244,838 B2
• Filed: 06/29/2009
• Issued: 08/14/2012
• Est. Priority Date: 03/30/2009
• Status: Active Grant

• Current Assignee: Rockwell Automation Technologies Incorporated (Allen-Bradley Co., Inc.)
• Original Assignee: Rockwell Automation Technologies Incorporated (Allen-Bradley Co., Inc.)
• Inventors: Balasubramanian, Sivaram, Moldovansky, Anatoly, Batke, Brian A.
• Primary Examiner(s): Avellino, Joseph
• Assistant Examiner(s): Park, Jeong S
• Application Number:
  US12/493,838
• Publication Number:
  US 20100246385A1
• Time in Patent Office: 1,142 Days
• Field of Search: 709220-222, 370/216, 370/222
• US Class Current: 709/221
• CPC Class Codes: G05B 19/0423 Input/output
• CPC Class Codes: H04L 41/0226 Mapping or translating multiple network management protocols
• CPC Class Codes: H04L 41/0806 for initial configuration or provisioning, e.g. plug-and-play
• CPC Class Codes: H04L 41/0856 by backing up or archiving configuration information
• CPC Class Codes: H04L 67/34 involving the movement of software or configuration parameters network booting or remote initial program loading [RIPL] G06F9/4416
• CPC Class Codes: H04L 69/08 Protocols for interworking; Protocol conversion
• CPC Class Codes: H04L 69/18 Multiprotocol handlers, e.g. single devices capable of handling multiple protocols

Abstract

A network for an industrial control system employs a ring topology that is normally opened by a ring supervisor at the ring supervisor. Upon failure of the network, the ring supervisor reconnects the ring to provide an alternative transmission path around the failure point. High speed operation is reconciled with the ability to use commercial switching integrated circuits through a dual communication channel of communicating a network state as either closed or open using both high-speed hardware handled beacon frames and low-speed software processed announce frames.

Claims

1. A ring network comprising:

a plurality of switching nodes providing layer 2 functionality to forward data frames between ports based on dynamically learnt MAC address routing tables, each switching node having at least a first and second port connectable to network media, the switching nodes arranged in a ring wherein the first and second ports of each switching node connect to different switching nodes of the ring and wherein at least one of the switching nodes is an active ring supervisor, at least one of the switching nodes further including first and second frame processing circuitry, wherein the first frame processing circuitry is faster than the second frame processing circuitry,

wherein the active ring supervisor is adapted to operate to;

(a) transmit beacon frames out of each port at a first rate and monitor the other port for reception of beacon frames, wherein the beacon frames indicate a state of operation of the ring network as a closed mode or an open mode, the beacon frames further including identifying data directing them to be processed by the first frame processing circuitry;

(b) transmit announce frames out of one port at a second rate slower than the first rate wherein the announce frames indicate the state of operation of the ring network as closed mode or open mode, the announce frames not having identifying data directing them to be processed by the first frame processing circuitry, the announce frames processed by the second frame processing circuitry;

(c) respond to a receipt of beacon frames between the first and second ports by blocking data frames between the first and second ports in an open mode;

(d) respond to failure of the beacon frames to traverse the ring by changing to a closed mode passing data frames between the first and second ports; and

wherein switching nodes that are not the active ring supervisor are adapted to operate to;

(a) pass beacon frames between the first and second ports;

(b) pass announce frames between the first and second ports; and

(c) respond to a change in the state of operation of the ring network deduced from either

(i) non-receipt of beacon frames on either port or;

(ii) receipt of beacon frames or announce frames indicating a change in operating between closed mode or open mode to reset their MAC address routing tables.

2. The ring network of claim 1 wherein at least some switching nodes that are not the active ring supervisor detect a change in the state of operation from the announce frames.

3. The ring network of claim 1, wherein at least some switching nodes that are not the active ring supervisor detect a change in the state of operation from data in the beacon frames.

4. The ring network of claim 1 wherein the switching nodes that are not the active ring supervisor further respond to a change of state from an open mode to a closed mode by checking for communication with immediate neighbor node on each of their ports and reporting back to the active ring supervisor if one port provides for no communication.

5. The ring network of claim 1 wherein the switching nodes that are not the active ring supervisor further respond to a detected physical layer failure on one port by reporting back to the ring supervisor indicating a failed port.

6. The ring network of claim 1 wherein the active supervisory node transitions from open mode to closed mode when one of non-supervisory ring node reports a physical layer failure.

7. The ring network of claim 1 wherein the active supervisory node initiates ring fault location diagnostics in closed mode and reports back fault location information to the user.

8. The ring network of claim 1 wherein at least some switching nodes that are not the active ring supervisor are commercial off-the-shelf managed switches.

9. The ring network of claim 1 wherein the beacon frame further indicates a current ring supervisor rank of the ring supervisor and wherein there are multiple potential ring supervisors in the ring network each having a unique supervisor rank and the multiple potential ring supervisors are adapted to operate as switching nodes that are not active ring supervisors so long as beacon frames exist indicating a current active ring supervisor with a dominant rank.

10. The ring network of claim 1 wherein the active ring supervisor in the closed mode responds to the receipt of beacons between both of its first and second ports immediately without waiting for an expiration of a predetermined time interval.

11. The ring network of claim 1 wherein the announce frames are transmitted at a rate of at less than one per 500 milliseconds.

12. The ring network of claim 1 wherein the beacon frames are transmitted at a rate greater than once per millisecond.

13. An IEEE 802.3 Ethernet ring topology supervising network switch for use with a ring network including a plurality of switching nodes providing Layer 2 functionality to forward data frames between ports based on dynamically learnt MAC address routing tables, each switching node having at least a first and second port connectable to network media, the switching nodes arranged in a ring wherein the first and second ports of each switching node connect to different switching nodes of the ring, and at least one of the switching nodes further including first and second frame processing circuitry, wherein the first frame processing circuitry is faster than the second frame processing circuitry, the supervising network switch comprising a processing unit coupled to a first and second network port and executing a stored program to:

(a) transmit beacon frames out of each port at a first rate and monitor the other port for reception of beacon frames, wherein the beacon frames indicate a state of operation of the ring network as a closed mode or an open mode, the beacon frames further including identifying data directing them to be processed by the first frame processing circuitry;

(b) transmit announce frames out of one port at a second rate slower than the first rate wherein the announce frames indicate the state of operation of the ring network as closed mode or open mode, the announce frames not having identifying data directing them to be processed by the first frame processing circuitry, the announce frames processed by the second frame processing circuitry;

(c) respond to a receipt of beacon frames between the first and second ports by blocking data frames between the first and second ports in an open mode and transmitting data indicating the change in different announce frames and beacon frames, to indicate a change to the open mode to cause other switching nodes to reset their MAC address routing tables;

(d) respond to failure of the beacon frames to traverse the ring by changing to a closed mode and passing data frames between the first and second ports and transmitting data in the announce frames and beacon frames to indicate a change to the closed mode to cause other switching nodes to reset their MAC address routing tables.

14. The ring network of claim 13 wherein the supervising network switch in the closed mode responds to the receipt of beacons between both of its first and second ports immediately without waiting for the expiration of a predetermined time interval.

15. The ring network of claim 13 wherein the supervising network switch initiates ring fault location diagnostics in closed mode and reports back fault location information to the user.

16. The ring network of claim 13 wherein at least some of the nodes not operating as a ring supervisor are Ethernet layer 2 switches that cannot monitor the beacon frames.

17. The ring network of claim 13 wherein the announce frames are transmitted at a rate of at less than one per 500 milliseconds.

18. The ring network of claim 13 wherein the beacon frames are transmitted at a rate greater than once per millisecond.

19. An IEEE 802.3 Ethernet ring network comprising:

a plurality of switching nodes providing Layer 2 functionality to forward data frames between ports based on dynamically learnt MAC address routing tables, each switching node having at least a first and second port connectable to network media, the switching nodes arranged in a ring wherein the first and second ports of each switching node connect to different switching nodes of the ring and wherein at least one of the switching nodes is an active ring supervisor, at least one of the switching nodes further including first and second frame processing circuitry, wherein the first frame processing circuitry is faster than the second frame processing circuitry;

wherein the active ring supervisor is adapted to operate to;

(a) transmit beacon frames out of each port at a first-rate and monitor the other port for reception of beacon frames, wherein the beacon frames indicate a state of operation of the ring network as a closed mode or an open mode and a current ring supervisor rank of the ring supervisor, the beacon frames further including identifying data directing them to be processed by the first frame processing circuitry;

(b) respond to a receipt of beacon frames between the first and second ports by blocking data frames between the first and second ports in an open mode and transmitting data in the beacon frames to indicate a change to the open mode to cause other switching nodes to reset their MAC address routing tables;

(c) respond to failure of the beacon frames to traverse the ring by passing data frames between the first and second ports and transmitting data in the beacon frames to indicate a change to a closed mode to cause other switching nodes to reset their MAC address routing tables;

wherein switching nodes that are not the active ring supervisor are adapted to operate to;

(a) pass beacon frames between the first and second ports;

(b) respond to a change in the state of operation of the ring network deduced either from non-receipt of beacon frames on either port or receipt of beacon frames on both ports or from the data in beacon frames as operating in closed mode or open mode to reset their MAC address routing tables; and

wherein there are multiple potential ring supervisors in the ring network each having a unique supervisor rank and the multiple potential ring supervisors are adapted to operate as switching nodes that are not active ring supervisors so long as beacon frames exist indicating a current active ring supervisor with a dominant rank.