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T640 Packet Forwarding Engine Architecture


The Packet Forwarding Engines provide the Layer 2 and Layer 3 packet switching, forwarding, and route lookup functions. In a maximum configuration with eight Type 3 FPCs installed, the Packet Forwarding Engines can forward up to 640 million packets per second (Mpps) for all packet sizes. The maximum aggregate throughput rate for the T640 router is 320 Gbps (full duplex). The Packet Forwarding Engines are implemented in ASICs that are physically located on the FPCs and the PICs.

Each Packet Forwarding Engine consists of the following components (see Data Flow Through the T640 Router):

  • Layer 2/Layer 3 Packet Processing ASIC, which performs Layer 2 and Layer 3 encapsulation and de-encapsulation, and manages the division and reassembly of packets within the T640 router.

  • Queuing and Memory Interface ASICs, which manage the buffering of data cells in memory and the queueing of notifications.

  • T-series Internet Processor, which provides the route lookup function.

  • Switch Interface ASICs, which extract the route lookup key and manage the flow of data cells across the switch fabric.

  • Media-specific ASICs on the PICs that perform control functions tailored to the PIC media types.