Packet Forwarding Engine - Juniper M40 Hardware Manual

Figure 2: Rear View of Chassis
Upper impeller assembly

Packet Forwarding Engine

The Packet Forwarding Engine is a multicomponent system that uses application-specific
integrated circuits (ASICs) to perform Layer 2 and Layer 3 packet switching, route lookups,
and packet forwarding. The ASICs include the Distributed Buffer Manager ASIC, I/O Manager
ASIC, Internet Processor or Internet Processor II ASIC, and various media-specific controllers.
The Packet Forwarding Engine has the following components:
Center rack-mounting ear
Fan tray
Routing Engine housing
LS-120 drive
ESD point
Power supply A
Power supply B
Backplane—Forms the rear of the FPC card cage, distributes power from the power
supplies, and transfers packets and signals between router components, which plug into
it.
Physical Interface Cards (PICs)—Physically connect the router to network media such as
OC-12 ATM, OC-12 and OC-48 SONET/SDH, Channelized OC-12, and Gigabit Ethernet.
PICs are housed in FPCs.
Flexible PIC Concentrators (FPCs)—Process incoming and outgoing packets. From one
to eight FPCs can plug into the backplane from the front of the chassis. Each FPC
accommodates up to four Physical Interface Cards (PICs).
System Control Board (SCB)—Performs route lookup, filtering, and switching. The SCB
installs into the backplane from the front of the chassis.
Front rack-mounting ear
Hardware Component Overview
Packet Forwarding Engine
9