Fault-tolerant maintenance bus protocol and method for using the same

• US 6,691,257 B1
• Filed: 04/13/2000
• Issued: 02/10/2004
• Est. Priority Date: 04/13/2000
• Status: Expired due to Term

• Current Assignee: Stratus Technologies Ireland Ltd. (Stratus Technologies Bermuda Holdings Ltd.)
• Original Assignee: Stratus Technologies Bermuda Ltd. (Stratus Technologies Bermuda Holdings Ltd.)
• Inventors: Suffin, A. Charles
• Primary Examiner(s): Baderman, Scott
• Assistant Examiner(s): CHU, GABRIEL L
• Application Number:
  US09/548,202
• Time in Patent Office: 1,398 Days
• Field of Search: 714/43, 714/56, 714/2, 714/3, 714/7, 714/5, 714/35, 714/48, 714/49, 714/52, 710/100, 710/120, 710/119, 710/312, 710/306, 710/311
• US Class Current: 714/43
• CPC Class Codes: G06F 11/1443 Transmit or communication errors
• CPC Class Codes: G06F 11/2005 using redundant communication controllers
• CPC Class Codes: G06F 11/2007 using redundant communication media
• CPC Class Codes: G06F 11/2038 with a single idle spare processing component
• CPC Class Codes: G06F 11/2043 where the redundant components share a common memory address space

Abstract

A fault-tolerant maintenance bus protocol and method for using the same enables communication between a command module located on a parent maintenance bus and a plurality of subsystem components joined together on a child maintenance bus. The child maintenance bus is interconnected to a bridge assembly that directs messages formatted in the protocol between the subsystem components and the command module through the bridge. The protocol includes a command message structure that uniquely addresses the bridge assembly. It also includes a command string, a command data string for communicating with one of the subsystem components and a command error-checking string. A response message structure is generated by the bridge in response to a command message. The response message uniquely addresses the command module. It includes error and status strings with respect to execution of the command message, a response data string for communicating with the command module and a response error-checking string.

Claims

1. A fault-tolerant maintenance bus protocol for communicating between a command module located on a parent maintenance bus and a plurality of subsystem components joined together on a child maintenance bus, wherein the child maintenance bus is interconnected to a bridge assembly that directs messages formatted in the protocol between the subsystem components and the command module through the bridge, the protocol comprising:

a command message structure that uniquely addresses the bridge assembly, and that includes a command string, a command data string for communicating with one of the subsystem components, a tag uniquely identifying a packet, and a command error-checking string; and

a response message structure that uniquely addresses the command module, and that includes error and status strings with respect to execution of the command message, the error string including an error code for identifying a specific error, the response message structure further including a response data string for communicating with the command module, and a response error-checking string.

2. A fault-tolerant maintenance bus protocol for communicating between a command module located on a parent maintenance bus and a plurality of subsystem components joined together on a child maintenance bus, wherein the child maintenance bus is interconnected to a bridge assembly that directs messages formatted in the protocol between the subsystem components and the command module through the bridge, the protocol comprising:

a command message structure that uniquely addresses the bridge assembly, and that includes a command string, a command data string for communicating with one of the subsystem components and a command error-checking string, the command string positioned on the structure directly following a bridge address string;

a response message structure that uniquely addresses the command module, and that includes error and status strings with respect to execution of the command message, a response data string for communicating with the command module and a response error-checking string; and

a response string directly following a command module address string, the response string having a unique value indicative of a response message structure.

3. The protocol as set forth in claim 2 wherein the plurality of subsystem components are contained on a circuit board having a plurality of components, the circuit board being located on the parent maintenance bus and the command string includes command information formatted to instruct the bridge to power-up the plurality of components on the circuit board.

4. The protocol as set forth in claim 3 wherein the command data string includes command instructions formatted for one of the subsystem components.

5. The protocol as set forth in claim 4 wherein the response data string includes information provided by one of the subsystem components.

6. The protocol as set forth in claim 5 wherein the status and error strings include codes specifying erroneous conditions in execution of the command string.

7. The protocol as set forth in claim 6 wherein the command error-checking string and the response error-checking string each include an identical tag string, the tag string being initially provided by the command module in the command message structure and being returned by the bridge in the response message structure.

8. The protocol as set forth in claim 7 wherein the command error-checking string and the response error-checking string each include a checksum string indicative of a total length of the command message structure and the response message structure respectively.

9. The protocol as set forth in claim 6 wherein the bridge address string is adapted to address one of either the bridge or another bridge residing on the circuit board thereon each of the bridge and the other bridge being joined to the child bus and each of the bridge and the other bridge having the same address.

10. The protocol as set forth in claim 9 wherein each of the command message structure and the response message structure are adapted to travel between the command module and the other bridge over another parent maintenance bus connected to the other bridge.

11. The protocol as set forth in claim 6 wherein the response string provides the bridge with address data for directing the response message structure.

12. The protocol as set forth in claim 11 wherein the command data string includes information for identifying a subordinate bridge in the child maintenance bus, whereby the command message structure is routed through the subordinate bridge to remote circuitry.

13. A method for using a fault-tolerant maintenance bus protocol for communicating between a command module located on a parent maintenance bus and a plurality of subsystem components joined together on a child maintenance bus, wherein the child maintenance bus is interconnected to a bridge assembly that directs messages formatted in the protocol between the subsystem components and the command module through the bridge, the method comprising the steps of:

transmitting, from the command module, a command message structure that uniquely addresses the bridge assembly, and that includes a command string, a command data string for communicating with one of the subsystem components, a tag uniquely identifying a packet, and a command error-checking string; and

transmitting, from the bridge, a response message structure that uniquely addresses the command module, and that includes error and status strings with respect to execution of the command message, the error string including an error code for identifying a specific error, the response message structure further including a response data string for communicating with the command module, and a response error-checking string.

14. A method for using a fault-tolerant maintenance bus protocol for communicating between a command module located on a parent maintenance bus and a plurality of subsystem components joined together on a child maintenance bus, wherein the child maintenance bus is interconnected to a bridge assembly that directs messages formatted in the protocol between the subsystem components and the command module through the bridge, the method comprising the steps of:

selectively transmitting, from the command module, a command message structure that uniquely addresses the bridge assembly, and that includes a command string, a command data string for communicating with one of the subsystem components and a command error-checking string;

providing within the command message structure an address string that identifies each of the bridge and the other bridge; and

transmitting, from the bridge, a response message structure that uniquely addresses the command module, and that includes error and status strings with respect to execution of the command message, a response data string for communicating with the command module and a response error-checking string,

wherein the command message structure and the response message structure are transmitted over one of either the parent maintenance bus to the bridge or to another parent maintenance bus to another bridge, each of the bridge and the other bridge being interconnected to the child maintenance bus.

15. The method as set forth in claim 14 further comprising providing information with respect to a selected one of the subsystem components in the command data string and the response data string.

16. The method as set forth in claim 15 wherein the step of transmitting command message structure includes providing the bridge with address data in the response string for subsequent directing the response message structure.

17. The method as set forth in claim 16 further comprising providing, in the command data string, information for identifying a subordinate bridge in the child maintenance bus, whereby the command message structure is routed through the subordinate bridge to remote circuitry.