Juniper JUNOS - NETWORK OPERATION GUIDE REV1 Network Operation Manual page 130

JUNOS Internet Software Network Operations Guide: Hardware
!
94
Understanding Key Router Components
! Data Flow Through the M320 Router and T640 Routing Node Packet
Forwarding Engine on page 101
! Data Flow Through the T320 Router and T640 Routing Node Packet Forwarding
Engine on page 103
Data Flow Through the M5 and M10 Router Packet Forwarding Engine
Data flows through the M5 and M10 router Packet Forwarding Engine in the
sequence shown in Figure 13:
Figure 13: M5 and M10 Router Packet Forwarding Engine Components and Data Flow
PIC
Packet
Controller
in
PIC
Packet
Controller
out
= ASIC
1. Packets arrive at an incoming PIC interface.
2. The PIC passes the packets through the midplane to the FEB, where the I/O
Manager ASIC breaks them into 64-byte cells.
3. The Distributed Buffer Manager ASIC on the FEB distributes the data cells
throughout memory banks on the FEB.
4. The Internet Processor II ASIC on the FEB performs route lookups and makes
forwarding decisions.
5. The Internet Processor II ASIC notifies a second Distributed Buffer Manager
ASIC on the FEB, which forwards the notification to the outgoing interface.
6. The I/O Manager ASIC on the FEB reassembles data cells in shared memory
into data packets as they are ready for transmission and passes them to the
outgoing PIC through the midplane.
7. The outgoing PIC transmits the data packets.
Midplane
FEB
Distributed
Buffer
Manager
I/O
Manager
Distributed
Buffer
Manager
Routing
Engine
Internet
Processor
II