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

摘要

A fault-tolerant maintenance bus architecture and protocol for use therewith provides dual maintenance buses interconnecting each of a plurality of parent circuit boards. The two maintenance buses are each connected to a pair of system management modules (SMMs) that are configured to perform a variety of maintenance bus activities. Within each parent board are a pair of redundant bridges each having a unique address. One bridge is connected to the first maintenance bus while a second bridge is connected to the second maintenance bus of the pair. A child maintenance bus interconnects the two bridges on child circuit board. The child maintenance bus is interconnected to a bridge assembly that itself 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.