Intel Intel NetStructure Single Board Computer, MPCBL0010 - page 117

MPCBL0010 SBC—Hardware Management Overview
Intel NetStructure® MPCBL0010 Single Board Computer
Technical Product Specification October 2006
116 Order Number: 304120
If an IPMB bus fault or IPMC failure occurs, IPMB isolators are used to switch and
isolate the backplane/system IPMB bus from the faulted SBC board. Where possible,
the IPMC activates the redundant IPMB bus to re-establish system management
communication to report the fault.
The onboard DC voltages, currents, and temperature are monitored by the IPMC
microcontroller. The IPMC will log an event into the ShMC SEL if any of the thresholds
are exceeded.
To increase the reliability of the MPCBL0010 SBC management subsystem, an external
watchdog supervisor is implemented only for the IPMC . The IPMC strobes the external
watchdog at two-second intervals to ensure continuity of operation of the board’s
management subsystem. If the IPMC ceases to strobe the watchdog supervisor, the
watchdog isolates the IPMC from the IPMBs and resets the IPMC. The watchdog
supervisor does not reset the payload power and the restart of the IPMC does not affect
the payload. It restores the previous hot swap state and power level negotiated with
the shelf manager. The watchdog timeout expires after six seconds if strobes are not
generated. The external watchdog supervisor is not configurable and should not be
confused with the IPMI v1.5 watchdog timer commands.
This external watchdog of the IPMC is implemented in a second microcontroller called
the Firmware Upgrade Manager (FWUM). This microcontroller is responsible for
monitoring the IPMC and for managing the IPMC fail safe firmware upgrade process.
Figure 22. IPMC Block Diagram