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เอกสารอ้างอิง Network_10G ข้อ 4.3

Overview for Junos OS

software features once and share the features across product lines simultaneously.
Because features are common to a single source, generally these features are
implemented the same way for all of the product lines, reducing the training required to
learn different tools and methods for each product. Furthermore, because all Juniper
Networks products use the same code base, interoperability among products is not an
issue.
One Software Release

Each new version of Junos OS is released concurrently for all product lines following a
preset schedule. Each new version of software includes working features released in
previous versions of the software and must achieve zero critical regression errors. This
discipline ensures reliable operations for the entire release.
One Modular Software 4.3.2

Although individual architecture modules of Junos OS communicate through well-defined
interfaces, each module runs in its own protected memory space, preventing one module
from disrupting another. It also enables the independent restart of each module as
necessary. This is in contrast to monolithic operating systems for which a malfunction
in one module can ripple to other modules, possibly causing a full system crash or restart.
This modular Junos OS architecture provides a high level of performance, high availability,
security, and device scalability not found in other operating systems.
Junos OS is preinstalled on your Juniper Networks device when you receive it from the
factory. When you first power on the device, all software starts automatically. You then
configure the software so that the device can participate in your network.

You can upgrade the device software as new features are added or software problems
are fixed. You obtain new software by downloading images from the Juniper Networks
Support Web page onto your device or another system on your local network, then install
the software upgrade on the device.
Juniper Networks devices run only binaries supplied by Juniper Networks. Each Junos OS
image includes a digitally signed manifest of executables, which are registered with the
system only if the signature can be validated. Junos OS will not execute any binary without
a registered fingerprint. This feature protects the system against unauthorized software
and activity that might compromise the integrity of your network devices.

Related • Junos OS Configuration Basics on page 39
Documentation
• Junos OS Architecture Overview on page 5
• Router Hardware Components on page 7
• Junos OS Commit Model for Configurations on page 43
• Junos OS Routing Engine Components and Processes on page 8

• Junos OS Support for IPv4 Routing Protocols on page 19
• Junos OS Support for IPv6 Routing Protocols on page 20
• Junos OS Routing and Forwarding Tables on page 21

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