Routing Engine Functions; Figure 34: Routing Engine Architecture - Juniper M Series Monitoring And Troubleshooting Manual

M Series and T Series Routers Monitoring and Troubleshooting Guide

Routing Engine Functions

138

Figure 34: Routing Engine Architecture

The Routing Engine handles all the routing protocol processes, as well as other software
processes that control the router interfaces, system management, and user access to
the router. These routing and software processes run on top of a kernel that interacts
with the T-series Internet Processor in the Packet Forwarding Engine.
The Routing Engine provides the following functions:
Routing protocol packet processing—All routing protocol packets from the network
are directed to the Routing Engine, and hence do not delay the Packet Forwarding
Engine unnecessarily.
Software modularity—By dividing the different software functions into separate
processes, the failure of one process is isolated from others and has little or no effect
on them.
In-depth Internet functionality—Each routing protocol is implemented with a complete
set of Internet features and provides full flexibility for advertising, filtering, and modifying
routes. Routing policies are set according to route parameters (such as prefix, prefix
lengths, and BGP attributes).
Scalability—The Junos OS routing tables are designed to hold all the routes in current
and imminent networks. Additionally, the Junos OS efficiently supports large numbers
of interfaces and virtual circuits.
Management interface—Different levels of system management practices are provided,
including a command-line interface (CLI) and SNMP.
Storage and change management—Configuration files, system images, and microcode
can be held and maintained in primary and secondary storage systems, permitting
local or remote upgrades.
Efficiency and flexibility monitoring—The router permits alarm handling and packet
counting. For example, the router allows information to be gathered on every port,
without adversely affecting packet forwarding performance.
The Routing Engine constructs and maintains one or more routing tables (see
on page 139). From the routing tables, the Routing Engine derives a table of active routes,
Figure 35
Copyright © 2012, Juniper Networks, Inc.