Data Flow Through The Packet Forwarding Engine - Juniper M10i Hardware Manual

M10i Internet Router Hardware Guide

Data Flow Through the Packet Forwarding Engine

Use of ASICs promotes efficient movement of data packets through the system.
Packets flow through the Packet Forwarding Engine in the following sequence (see
Figure 12
1.
2.
3.
4.
5.
6.
34
Packet Forwarding Engine Architecture
Midplane—Transports packets, notifications, and other signals between the PICs
and the Packet Forwarding Engine (as well as other system components).
Physical Interface Card (PIC)—Physically connects the router to fiber-optic or
digital network media. A controller ASIC in each PIC performs control functions
specific to the PIC media type.
Compact Forwarding Engine Board (CFEB)—Hosts an integrated ASIC, which
makes forwarding decisions, distributes data cells to the shared memory, and
directs data packets when they are ready for transmission.
):
Packets arrive at an incoming networking interface.
The networking interface passes the packets to the CFEB, where the integrated
ASIC processes the packet headers, divides the packets into 64-byte data cells,
and distributes the data cells throughout the memory buffer.
The integrated ASIC on the CFEB performs a route lookup for each packet and
decides how to forward it.
If services are configured for the packet, the integrated ASIC reassembles
a.
the packet and passes them to the services interface.
The services interface passes the packet to the CFEB, where the integrated
b.
ASIC processes the packet, divides the packet into 64-byte cells, and
distributes the data cells throughout the memory buffer.
The integrated ASIC performs a second route lookup for each packet and
c.
decides how to forward it.
The integrated ASIC notifies the outbound networking interface.
The integrated ASIC reassembles data cells stored in shared memory into data
packets as they are ready for transmission and passes them to the outbound
networking interface.
The outbound networking interface transmits the data packets.