Switch Startup Process

1. Switch startup commences when standby power is enabled for the Chassis Management Controllers (CMCs). Standby power is applied when the power supplies are energized.

2. The redundant CMCs perform self-tests and determine if the other instance is present and operational. The CMCs then negotiate active and standby roles.

3. The active CMC becomes available on the management network.

4. The CMC checks that the required number of power supplies are present and operational in each power domain, and then activates full power mode for each power supply.

5. If the power supply population is functional, commands to the CMC enable standby power for each fabric card and line card. Standby power is provided to each card sequentially to avoid overloading the power supplies.

6. The CMC performs further discovery and checks of the fabric cards and line cards using Intelligent Platform Management interface (IPMI) communication with the Intelligent Platform Management controllers (IPMCs) in the fabric cards and line cards.

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   Note - Conversion from standby to full-power mode can be an automatic or explicitly controlled operation.

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7. The CMC determines if the available power is sufficient for the number of fabric cards and line cards in each power domain, and then sends commands to the CMC to initiate power-on sequencing. All the fabric cards are powered on first, followed by the line cards.

8. After power-on of each fabric card, the CMC checks that a sufficient number of fans on the fabric card are fully operational. If too few fans are operational, the fabric card is shut down.

9. Completing the fabric card power-on, the CMC checks that both the card and supplied power status is okay.

10. When all fabric cards have been powered on and checked, the CMC re-evaluates the cooling capacity to ensure that line cards are only powered on if sufficient cooling capacity is available.

11. The line cards are then powered on, as directed by commands to the CMC.

12. When a fabric card or line card is instructed to go to full power, the card’s on-board IPMC verifies that the local power sensors indicate okay status, and then enables power for the switch chips.

13. The IPMC performs basic card self-test functions that include being able to read sensible data from the key I²C slave devices on the card. The switch chips also have I²C slave devices.

14. The IPMC constantly monitors the various sensors and signals on the card, including cable and link status.

15. The IPMC enables all InfiniBand ports and links on the fabric cards, and all internal ports and links on the line cards. The CXP connectors on the line cards are not enabled until the IPMC is instructed to do so by the CMC.

16. After power sequencing and basic tests have been completed, the IPMC reports the card as operational to the CMC.

17. When the CMC has received operational status confirmation from all cards, the CMC correlates InfiniBand link state information to verify that all relevant internal links have become operational.

18. Links that fail to become operational are recorded.

19. The CMC then instructs the IPMCs on the line cards to enable external links through the CXP connectors on the line cards.