M10i Internet Router Hardware Guide

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.

For a description of the Routing Engine's role in router architecture, see “Routing

Engine Architecture” on page 35.

One or two Routing Engines can be installed into the midplane from the front of the chassis, as shown in Figure 1. If two Routing Engines are installed, the High-Availability Chassis Manager (HCM) determines which is the master and which is in standby mode (and so performs no functions). By default, the Routing Engine in the slot labeled RE0 is the master.

To change the default master Routing Engine, include the appropriate

[edit chassis redundancy routing-engine]statement in the configuration, as described in the section about Routing Engine redundancy in the JUNOS System Basics Configuration Guide.

The Routing Engine is hot-pluggable, as described in “Field-Replaceable Units (FRUs)” on page 3. Removal or failure of the standby Routing Engine does not affect router function. If the master Routing Engine is removed from the chassis, the effect depends on whether two Routing Engines are installed:

With the default router configuration, in case of failure you must correct the problem manually. You can issue the appropriate

request chassis routing-engine master command to switch mastership to the other Routing Engine, for example. For information about the command, see the JUNOS System Basics and Services Command Reference.

On routers with two installed Routing Engines, you can configure graceful switchover of Routing Engines or automatic Routing Engine mastership failover. If the Routing Engines are configured for graceful switchover, the standby Routing Engine immediately assumes Routing Engine functions and there is no interruption to packet forwarding. Otherwise, packet forwarding halts while the standby Routing Engine becomes the master and the Packet Forwarding Engine components reset and connect to the new master Routing Engine. For information about configuring graceful switchover or automatic mastership failover, see the section about Routing Engine redundancy in the JUNOS System Basics Configuration Guide.

We recommend you run JUNOS Release 7.0 or later on the M10i router to support graceful switchover.

For replacement instructions, see “Replacing the Routing Engine” on page 121.

Routing Engine Components

The Routing Engine has the following major components (see Figure 5):

14Routing Engine

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Juniper Networks M10i manual Routing Engine Components