Juniper Networks MX240 Replacing Host Subsystem Components, Taking the Host Subsystem Offline

MX240 Ethernet Services Router Hardware Guide

Figure 42: Installing the Air Filter in an MX240 Router

Replacing Host Subsystem Components

To replace a host subsystem, use the following procedures:

■Taking the Host Subsystem Offline on page 96

■Replacing an SCB on page 97

Taking the Host Subsystem Offline

The host subsystem is taken offline and brought online as a unit. Before you replace an SCB or a Routing Engine, you must take the host subsystem offline. The host subsystem is hot-pluggable.

If the router has only one host subsystem, taking the host subsystem offline causes the router to shut down.

Normally, if two host subsystems are installed in the router, RE0 functions as the master and RE1 functions as the backup. You can remove the backup host subsystem (or either of its components) without interrupting the functioning of the router. If you take the master host subsystem offline, the backup host subsystem becomes the master (the router might reboot, depending on your configuration). The effect of taking the master host subsystem varies depending on your configuration of high availability features.

High availability features include Routing Engine redundancy, graceful Routing Engine switchover (GRES), nonstop bridging, nonstop active routing, graceful restart for routing protocols, Virtual Router Redundancy Protocol (VRRP), and unified in-service software upgrade (ISSU). Some high availability features are not supported by all platforms and all PICs. For information about the first supported JUNOS release for these features by PIC and platform, see the JUNOS High Availability Configuration Guide.

To take a host subsystem offline:

96■ Replacing Host Subsystem Components