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 OS Processes
The Junos OS 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. In addition, because each process is a separate software
package, you can selectively upgrade all or part of the Junos OS, for added flexibility.
Table 17 on page 24 describes the primary Junos OS processes.
Table 98: Junos OS Processes
Description
Name
Process
Detects hardware on the system that is used to configure network interfaces.
Monitors the physical status of hardware components and field-replaceable units
(FRUs), detecting when environment sensors such as temperature sensors are triggered.
Relays signals and interrupts—for example, when devices are taken offline, so that the
system can close sessions and shut down gracefully.
chassisd
Chassis process
Handles Layer 2 switching functionality such as MAC address learning, Spanning Tree
protocol and access port security. The process is also responsible for managing Ethernet
switching interfaces, VLANs, and VLAN interfaces.
Manages Ethernet switching interfaces, VLANs, and VLAN interfaces.
eswd
Ethernet
switching
process
Defines how routing protocols operate on the switch. The overall performance of the
switch is largely determined by the effectiveness of the forwarding process.
pfem
Forwarding
process
Configures and monitors network interfaces by defining physical characteristics such
as link encapsulation, hold times, and keepalive timers.
dcd
Interface
process
493
Copyright © 2010, Juniper Networks, Inc.
Chapter 28: User and Access Management on EX Series Switches Overview
Summary of Contents for JUNOS OS 10.3 - SOFTWARE
Page 325: ...CHAPTER 17 Operational Mode Commands for System Setup 229 Copyright 2010 Juniper Networks Inc ...
Page 1323: ...CHAPTER 56 Operational Mode Commands for Interfaces 1227 Copyright 2010 Juniper Networks Inc ...
Page 2841: ...CHAPTER 86 Operational Commands for 802 1X 2745 Copyright 2010 Juniper Networks Inc ...
Page 3367: ...CHAPTER 113 Operational Mode Commands for CoS 3271 Copyright 2010 Juniper Networks Inc ...
Page 3435: ...CHAPTER 120 Operational Mode Commands for PoE 3339 Copyright 2010 Juniper Networks Inc ...
Page 3529: ...CHAPTER 126 Operational Mode Commands for MPLS 3433 Copyright 2010 Juniper Networks Inc ...
