Juniper Networks J6350, J4350 Routing Engine and Packet Forwarding Engine, Kernel and Microkernel

J2320, J2350, J4350, and J6350 Services Router Getting Started Guide

Routing Engine and Packet Forwarding Engine

A Services Router has two primary software processing components:

■Routing Engine—The Routing Engine provides three main functions:

■Creates the packet forwarding switch fabric for the Services Router, 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 router and controls the routing protocols that run on the router.

■Provides control and monitoring functions for the router, including controlling power and monitoring system status.

■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.

For information about Routing Engine hardware, see “J2320 and J2350 Routing

Engine Hardware” on page 18 and “J4350 and J6350 Routing Engine

Hardware” on page 31.

Kernel and Microkernel

The Routing Engine kernel provides the underlying infrastructure for all JUNOS software processes by doing the following:

■Linking the routing tables maintained by the routing protocol process with the forwarding table maintained by the Routing Engine

■Coordinating communication with the Packet Forwarding Engine, primarily by synchronizing the Packet Forwarding Engine’s forwarding table with the master forwarding table maintained by the Routing Engine

The microkernel contains device drivers and processes that the Packet Forwarding Engine uses to govern the flow of packets through the Services Router.

JUNOS Software Processes

The JUNOS software running on the Routing Engine and Packet Forwarding Engine consists of multiple processes that are responsible for individual Services Router functions.

The separation of functions provides operational stability, because each process accesses its own protected memory space. In addition, because each process is a separate software package, you can selectively upgrade all or part of the JUNOS software, for added flexibility.

Table 17 on page 41 describes the primary JUNOS software processes.

40■ Software Overview