Cisco Systems OL-11497-03 manual Maintenance Bus, Power-Up/Down Control, Device Discovery

Chapter 1 Product Overview

Maintenance Bus

Maintenance Bus

The Cisco 12006 and Cisco 12406 router maintenance bus and MBus modules manage the maintenance functions of the system. The MBus is integrated into the backplane and consists of two separate buses, providing MBus redundancy.

Both MBus networks are linked to all the following items:

•Route processor and line cards

•CSCs, SFCs, and alarm cards

•Power modules

•Blower module

The MBus module located on each component communicates over the MBus and is powered by DC voltage directly from the alarm card. The MBus performs the functions of power-up/down control for each component, component (device) discovery, code download, diagnostics, and environmental monitoring and alarms.

Power-Up/Down Control

Each MBus module directly controls the DC-DC converters on the component on which it is mounted, based on commands the component receives from its on-board EPROM and from the RP. Each MBus module is tied directly to DC voltage from the alarm card.

When power is applied to the router, all MBus modules immediately power up. The MBus modules on the RP and CSC immediately turn on the DC-DC converter, powering up the respective card. The line card MBus module waits to power up the line card until it receives a command from the RP.

Device Discovery

The RP uses the MBus to detect the system configuration. The RP sends a message over the MBus requesting identity information from all installed devices. The responses provide component type, as well as slot numbers for the line cards, CSCs, SFCs, and alarm cards.

	Cisco 12006 and Cisco 12406 Router Installation and Configuration Guide
OL-11497-03		1-13