Hardware Component Overview
Routing Engine
15
Table 4: States for SCB LEDs
Routing Engine
The Routing Engine is an Intel-based PCI platform that runs JUNOS Internet software.
Software processes that run on the Routing Engine maintain the routing tables, manage the
routing protocols used on the router, control the router's interfaces, control some chassis
components, and provide the interface for system management and user access to the
router.
The Routing Engine installs into the rear of the chassis, in a compartment behind the card
cage (see Figure 2). For information about the routing architecture, see “System Architecture
Overview” on page 31.
The Routing Engine is hot-pluggable, as described in “Field-Replaceable Units (FRUs)” on
page 4. For replacement instructions, see “Maintain and Replace Routing Engine
Components” on page 173.
Routing Engine Components
The Routing Engine (shown in Figure 6) is a two-board system with the following
components:
CPU—Runs JUNOS Internet software to maintain the router’s routing tables and routing
protocols. It has a Pentium-class processor.
SDRAM—Provides storage for the routing and forwarding tables and for other Routing
Engine processes.
Compact flash drive—Provides primary storage for software images, configuration files,
and microcode. The drive is fixed and inaccessible from outside the router.
Hard drive—Provides secondary storage for log files, memory dumps, and rebooting the
system if the flash drive fails.
PC card slot—Accepts a removable PC card, which stores software images for system
upgrades.
Interfaces for out-of-band management access—Provide information about Routing
Engine status to devices (console, laptop, or terminal server) that can be attached to
access ports located
on the craft interface
.
EEPROM—Stores the serial number of the Routing Engine.
Label
Color
State
Description
ACTIVE
Green
Flashing (pulsed with out-time
proportional to traffic)
I/O interrupts are occurring.
RUN
Green
Blinking
SCB processor is running. Normally, the
blinking is faint and becomes bright only when
the SCB is processing many exceptions.
STAT1
Amber
Flashing
Internal diagnostics are running.
STAT2
