Availability Features
The OmniSwitch 8800
page 1-6
OmniSwitch 8800 Hardware Users Guide
December 2004
Power Checking Sequence
The power checking sequence is another built-in Availability feature. This feature helps regulate power in
the switch whenever the switch is booted or an NI module is installed in the chassis.
The sequence is a joint effort among the CMM, the SFMs, the NI modules, and the power supplies. During
the boot sequence, the primary CMM automatically compares the power consumption required by
installed NIs with the power available from the power supplies. If there is not adequate power to support
all NIs, the CMM will power on only the supported number of NIs, starting from the first NI slot position.
Important.
During the power checking sequence, CMMs receive priority and are always powered on first.
SFMs are powered on next, then NI modules are powered on sequentially by slot position. In other words,
the NI in slot 1 is powered on, then slot 2, then slot 3, etc. For information on slot positions, refer to
Chapter 2, “Chassis and Power Supplies.”
Installing a New NI into a Running Chassis
When an NI module is installed in the chassis, only a small portion of the circuitry is initially powered up.
The CMM immediately reads the incoming module’s ID and determines how much power the module will
require. If the number of power supplies installed in the chassis can provide sufficient power, the CMM
turns on the incoming module. If the number of installed power supplies cannot provide sufficient power,
the incoming NI will remain powered off.
