Juniper JUNOS - NETWORK OPERATION GUIDE REV1 User Manual

JUNOS Internet Software Network Operations Guide: Hardware
100 ! Understanding Key Router Components
Data Flow Through the M160 Router Packet Forwarding Engine
Data flows through the M160 router Packet Forwarding Engine in the sequence
shown in Figure 19.
Figure 19: M160 Router Packet Forwarding Engine Components and Data Flow
1. Packets arrive at an incoming PIC interface.
2. The PIC passes the packets to the FPC, where the Packet Director ASIC
distributes them among the I/O Manager ASICs.
3. The I/O Manager ASICs process the packet headers, divide the packets into
64-byte data cells, and pass the cells through the midplane to the SFMs.
4. The Distributed Buffer Manager ASICs on the SFMs distribute the data cells
throughout memory buffers located on and shared by all the FPCs.
5. For each packet, an Internet Processor II ASIC on an SFM performs a route
lookup and decides how to forward the packet.
6. The Internet Processor II ASIC notifies a second Distributed Buffer Manager
ASIC (on the SFM) of the forwarding decision, and the Distributed Buffer
Manager ASIC forwards the notification to the FPC that hosts the appropriate
outbound interface.
7. The I/O Manager ASIC on the FPC reassembles data cells in shared memory
into data packets as they are ready for transmission and passes them through
the Packet Director ASIC to the outbound PIC.
8. The outbound PIC transmits the data packets.
1234
= ASIC
Distributed
Buffer
Manager
SFM
Routing
Engine
Internet
Processor II
Packet
Director
FPC
I/O
Manager
Packet
in
Packet
out
PIC
Controller
Midplane

Juniper JUNOS - NETWORK OPERATION GUIDE REV1 Specifications

General

Brand	Juniper
Model	JUNOS - NETWORK OPERATION GUIDE REV1
Category	Software
Language	English