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Packet Forwardin
gEngine
Description Value
Weight, minimum configuration 57 lb (25.8 kg)
Thermal output 2550 BTU/hour
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 fo
rwarding. The ASICs include the Distributed Buffer Manager ASIC, Internet
Processor II ASIC, I/O Manager ASIC, and media-specific controller ASICs.
The Packet F
orwardingEnginehasthefollowingcomponents:
• Midplane—Physically separates front and rear cavities inside the chassis, distributes
power from t
he power supplies, and transfers packets and signals between router
components, which plug into it.
• Physical In
terface Cards (PICs)—Physically connect the router to network media such
as OC-12/STM-4, OC-48/STM-16, Ethernet, and channelized interfaces.
• Flexible PI
C Concentrators (FPCs)—House PICs. On the M5 and M10 routers, FPCs are
built in (cannot be removed from the chassis as on some other M-series platforms).
• Forwardin
g Engine Board (FEB)—Performs route lookup, filtering, and switching. It
installs into the midplane from the rear of the chassis.
For inform
ation about Packet Forwarding Engine components, see the following sections:
• Midplane on page 8
• Physical Interface Cards (PICs) on page 9
• Flexible PIC Concentrators (FPCs) on page 10
• Forwarding Engine Board (FEB) on page 10
Midplane
The midplan
e is a panel located in the center of the chassis, running from side to side and
forming the rear of the PIC card cage (see Figure 4). All router components plug directly
into the midplane. The midplane contains an EEPROM that stores the serial number and
revision l
evel of the midplane.
The midplane performs the following functions:
• Transfer of packets—After being processed by a PIC, an incoming data packet crosses
themidplanetotheFEB.TheFEBperformsswitchingandforwardingfunctionsand
transfers
outgoing packets back across the midplane to the PICs for transmission
to the network.
8 M5 and M10 Internet Routers Hardware Guide