Power-On/Off Control - Cisco 12404 Installation And Configuration Manual

Maintenance Bus

Power-On/Off Control

Component Discovery
Code Download
Diagnostics
Cisco 12404 Internet Router Installation and Configuration Guide
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Each MBus module directly controls the DC–to–DC converters on the component
it is mounted on based on commands the component receives from its on-board
EPROM and from the RP. Each MBus module is tied directly to +5 VDC from the
consolidated fabric card.
When power is applied to the Cisco 12404 router, all MBus modules immediately
power on. The MBus modules on the RP and CSF card immediately turn on the
DC–to–DC converter, powering up the respective card. The line card MBus
module waits to power on the line card until it receives a command from the RP.
The RP can determine the system configuration using the MBus. A message is
sent from the RP over the MBus requesting all installed devices to identify
themselves. The response back provides component type, line card slot number,
and CSF card slot number.
A portion of the line card operating software can be downloaded from the RP to
the line card over the MBus. Because the MBus is relatively slow compared to the
CSF, only enough code is downloaded to the line card for it to access the CSF and
complete the download process.
The diagnostic software image is downloaded from the RP to the line card during
the test sequence.
Chapter 1 Product Overview
OL-11636-01