Figure 9: Unified Issu Example Topology - Juniper EX9200 Features Manual

Overview
Configuration
Copyright © 2017, Juniper Networks, Inc.
NOTE: Starting with Junos OS Release 16.1R1, while performing a unified
ISSU from a FreeBSD 6.1 based Junos OS to an upgraded FreeBSD 10.x
based Junos OS, the configuration must be validated on a remote host or
on a routing engine. The remote host or the routing engine must be running
a Junos OS with an upgraded FreeBSD. In addition, only a few selected
directories and files will be preserved while upgrading from FreeBSD 6.1
based Junos OS to FreeBSD 10.x based Junos OS. See
with Upgraded FreeBSD
with Upgraded FreeBSD)
This procedure can be used to upgrade M Series, T Series, MX Series, EX Series, and PTX
Series devices that have dual Routing Engines installed and support unified ISSU.
In the example, the hostnames, filenames, and FRUs are representational. When you
perform the procedure on your device, the hostnames, filenames, and FRUs are different.
The command output is truncated to only show the text of interest in this procedure.
Topology
Figure 9 on page 189 shows the topology used in this example.

Figure 9: Unified ISSU Example Topology

There are variations of the procedure depending on if you want to install the new software
on one or both Routing Engines and if you want to automatically reboot both Routing
Engines or manually reboot one of the Routing Engines.
In all cases, you must verify that dual Routing Engines are installed and that graceful
Routing Engine switchover (GRES) and nonstop active routing (NSR) are enabled. We
recommend that you back up the device software before the upgrade.
Chapter 17: Performing a Unified ISSU
and
request system software valdiate on (Junos OS
Upgrading Junos OS
189