Juniper Networks M10, M5 manual Packet Forwarding Engine, Midplane

Packet Forwarding Engine

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 forwarding. The ASICs include the Distributed Buffer Manager ASIC, Internet Processor II ASIC, I/O Manager ASIC, and media-specific controller ASICs.

The Packet Forwarding Engine has the following components:

•Midplane—Physically separates front and rear cavities inside the chassis, distributes power from the power supplies, and transfers packets and signals between router components, which plug into it.

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Physical Interface Cards (PICs)—Physically connect the router to network media such as OC-12/STM-4, OC-48/STM-16, Ethernet, and channelized interfaces.

Flexible PIC 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).

•Forwarding Engine Board (FEB)—Performs route lookup, filtering, and switching. It installs into the midplane from the rear of the chassis.

For information about Packet Forwarding Engine components, see the following sections:

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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 midplane 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 level of the midplane.

The midplane performs the following functions:

•Transfer of packets—After being processed by a PIC, an incoming data packet crosses the midplane to the FEB. The FEB performs switching and forwarding functions and transfers outgoing packets back across the midplane to the PICs for transmission

to the network.

8M5 and M10 Internet Routers Hardware Guide