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:

• 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.