Hardware Architecture Overview

Juniper Network routing platforms are made up of two basic routing components:

• Routing Engine—The Routing Engine controls the routing updates and system management.
• Packet Forwarding Engine (PFE)—The Packet Forwarding Engine performs Layer 2 and Layer 3 packet switching, route lookups, and packet forwarding.

From a system administration perspective, you install the software onto the Routing Engine and during the installation, the appropriate software is forwarded to other components as necessary. Each Routing Engine includes a CompactFlash card that stores the Junos OS. On the M Series, MX Series, T Series, and TX Matrix routers, the system also includes a hard drive that acts as a backup boot drive. The TX Matrix Plus router includes either a hard drive or a solid state drive as a backup boot drive.

Note: The MX80 router is a single-board router with a built-in Routing Engine and single Packet Forwarding Engine. On an MX80 router, the Junos OS is stored on dual, internal NAND flash devices. These devices provide the same functionality as a CompactFlash card and hard drive.

On routing platforms with dual Routing Engines, each Routing Engine is independent with regard to upgrading the software. To install new software on both Routing Engines, you need to install the new software on each Routing Engine. On platforms with dual Routing Engines configured for high availability, you can use the unified in-service software upgrade procedure to upgrade the software. For more information on this procedure, see the Junos High Availability Configuration Guide.