Cisco Systems XR 12404 manual Maintenance Bus, Power-On/Off Control, Component Discovery

Chapter 1 Cisco XR 12404 Router Overview

Maintenance Bus

Maintenance Bus

The Cisco XR 12404 router maintenance bus and MBus modules manage all of the maintenance functions of the system. The MBus consists of two separate busses (providing MBus redundancy). Each MBus is linked to all of the following.

•Line cards

•Route Processor

•CSF card

The MBus module located on each component, communicates over the MBus and is powered by +5 VDC directly from the fabric card. The MBus performs the functions of power-on/off control for each component, component (device) discovery, code download, diagnostics, and environmental monitoring and alarms.

Power-On/Off Control

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 route processor. Each MBus module is tied directly to +5 VDC from the consolidated fabric card.

When power is applied to the Cisco XR 12404 router, all MBus modules immediately power on. The MBus modules on the route processor 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 route processor.

Component Discovery

The route processor can determine the system configuration using the MBus. A message is sent from the route processor 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.

	Cisco XR 12404 Router Installation Guide
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