Understanding Software Infrastructure and Processes
Each switch runs the JUNOS software for EX-series switches on its general-purpose processors. JUNOS software includes processes for Internet Protocol (IP) routing and for managing interfaces, networks, and the chassis.
The JUNOS software runs on the Routing Engine. The Routing Engine kernel coordinates communication among the JUNOS software processes and provides a link to the Packet Forwarding Engine.
With the J-Web interface and the command-line interface (CLI) to the JUNOS software, you configure switching features and routing protocols and set the properties of network interfaces on your switch. After activating a software configuration, use either the J-Web or CLI user interface to monitor the switch, manage operations, and diagnose protocol and network connectivity problems.
Routing Engine and Packet Forwarding Engine
A switch has two primary software processing components:
- Packet Forwarding Engine—Processes packets; applies filters, routing policies, and other features; and forwards packets to the next hop along the route to their final destination.
- Routing Engine—Provides three main functions:
- Creates the packet forwarding switch fabric for the switch, providing route lookup, filtering, and switching on incoming data packets, then directing outbound packets to the appropriate interface for transmission to the network
- Maintains the routing tables used by the switch and controls the routing protocols that run on the switch.
- Provides control and monitoring functions for the switch, including controlling power and monitoring system status.
JUNOS Software Processes
The JUNOS software running on the Routing Engine and Packet Forwarding Engine consists of multiple processes that are responsible for individual functions.
The separation of functions provides operational stability, because each process accesses its own protected memory space.
Table 1 describes the primary JUNOS software processes.
Table 1: JUNOS Software Processes