Software Package Security; Installing Software On A Virtual Chassis; Engines; Installing Software Using Automatic Software Download - Juniper JUNOS OS 10.4 - FOR EX REV 1 Manual

Complete Software Guide for Junos
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OS for EX Series Ethernet Switches, Release 10.4
During a successful upgrade, the upgrade package removes all files from
completely reinstalls the existing software. It retains configuration files, and similar
information, such as secure shell and host keys, from the previous version. The previous
software package is preserved in a separate disk partition, and you can manually revert
back to it if necessary. If the software installation fails for any reason, such as loss of
power during the installation process, the system returns to the originally active installation
when you reboot.

Software Package Security

All Junos OS releases are delivered in signed packages that contain digital signatures to
ensure official Juniper Networks software. For more information about signed software
packages, see the
Junos OS Installation and Upgrade Guide.

Installing Software on a Virtual Chassis

You can connect individual Juniper Networks EX4200 Ethernet Switches together to
form one unit and manage the unit as a single chassis, called a Virtual Chassis. The Virtual
Chassis operates as a single network entity composed of members. Each member of a
Virtual Chassis runs a Junos OS package.
For ease of management, the Virtual Chassis provides flexible methods to upgrade
software releases. You can deploy a new software release to all members of a Virtual
Chassis or to only a particular member.
Installing Software on EX8200 Switches with Redundant Routing Engines
You can install software on an EX8200 switch with redundant Routing Engines in one
of two ways:
Perform a nonstop software upgrade (NSSU)—An NSSU upgrades both Routing
Engines with a single command and with a minimum of network disruption. An NSSU
takes advantage of graceful Routing Engine switchover (GRES) and nonstop active
routing (NSR) to ensure no disruption to the control plane. You can minimize disruption
to network traffic by defining link aggregation groups (LAGs) such that the member
links of each LAG reside on different line cards. The line cards are upgraded one at a
time, so that traffic continues to flow through the other line cards while a line card is
being upgraded.
You cannot use NSSU to downgrade the software running on a switch.
For more information about NSSU, see "Understanding Nonstop Software Upgrade
on EX Series Switches" on page 1176.
Upgrade each Routing Engine manually—You can perform a Junos OS installation on
each Routing Engine separately, starting with the backup Routing Engine. You can use
this procedure to downgrade the software running on a switch. See "Installing Software
on an EX8200 Switch with Redundant Routing Engines (CLI Procedure)" on page 85.

Installing Software Using Automatic Software Download

The automatic software download feature uses the DHCP message exchange process
to download and install software packages. Users can define a path to a software package
on the DHCP server and then the DHCP server communicates this path to EX Series
/var/tmp
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