The forwarding between the FPCs and PICs varies by routing platform.
An I/O Manager application-specific integrated circuit (ASIC) or ASICs on each FPC accept incoming data packets from the PICs on the FPC and divide each packet into 64-byte cells. The cells are transferred to the forwarding component. On the M40e routing platform, the forwarding component is the Switching and Forwarding Module (SFM).
An ASIC on the forwarding component distributes the cells among the memory buffers located on and shared by all installed FPCs. An I/O Manager ASIC or ASICs on the FPC reassemble the data cells into a packet and pass the packet to the appropriate PIC for transmission to the network.
Each Packet Forwarding Engine receives incoming packets from the PICs installed on the FPC and forwards them through the switch planes to the appropriate destination FPC and port. Each FPC contains data memory, which is managed by the Queuing and Memory Interface ASICs, and either one or two Packet Forwarding Engines.