Routing Engine Components - Juniper PTX Series Hardware Manual

Copyright © 2012, Juniper Networks, Inc.
the forwarding table in the Packet Forwarding Engine to be updated without interrupting
forwarding performance.
The Routing Engine includes the following functions and features:
Processing of routing protocol packets—The Routing Engine handles all packets that
concern routing protocols, freeing the Packet Forwarding Engine to handle only packets
that represent Internet traffic.
Software modularity—Because each software process is devoted to a different function
and uses a separate process space, the failure of one process has little or no effect on
the others.
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 (for example, prefix,
prefix lengths, and BGP attributes).
Scalability—Junos OS routing tables have been designed to hold all the routes in current
networks with ample capacity for expansion. Additionally, Junos OS can efficiently
support large numbers of interfaces and virtual circuits.
Management interface—Different levels of system management tools are provided,
including the Junos OS command-line interface (CLI), the Junos XML management
protocol, the craft interface, 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.
Monitoring efficiency and flexibility—The packet transport switch supports functions
such as alarm handling and packet counting on every port, without degrading
packet-forwarding performance.

Routing Engine Components

Each Routing Engine (shown in
components:
CPU—Runs Junos OS to maintain the routing tables and routing protocols.
DRAM—Provides storage for the routing and forwarding tables and for other Routing
Engine processes.
EEPROM—Stores the serial number of the Routing Engine.
Interfaces for management access—Provide information about Routing Engine status
to the external management devices (console, laptop, or terminal server) connected
to the management ports on the control board.
Chapter 3: PTX5000 Hardware Components Overview
Figure 25 on page 46) consists of the following
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