Juniper CBL-M40-PWR-AU ユーザーズマニュアル
System Architecture Overview
Routing Engine Architecture
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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):
through the Packet Forwarding Engine in the following sequence (see Figure 12):
1.
Packets arrive at an incoming PIC interface.
2.
The PIC passes the packets to the FPC, where the I/O Manager ASIC processes the
packet headers, divides the packets into 64-byte data cells, and passes the cells to the
backplane.
packet headers, divides the packets into 64-byte data cells, and passes the cells to the
backplane.
3.
The Distributed Buffer Manager ASIC on the backplane distributes the data cells
throughout the memory buffers located on and shared by all the FPCs.
throughout the memory buffers located on and shared by all the FPCs.
4.
The Internet Processor or Internet Processor II ASIC on the SCB performs route lookups
and makes forwarding decisions.
and makes forwarding decisions.
5.
The Internet Processor or Internet Processor II ASIC notifies a second Distributed Buffer
Manager ASIC on the backplane of the routing decision.
Manager ASIC on the backplane of the routing decision.
6.
The Distributed Buffer Manager ASIC forwards the notification to the FPC that hosts the
outbound PIC.
outbound PIC.
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 to the outbound PIC.
packets as they are ready for transmission and passes them to the outbound PIC.
8.
The outbound PIC transmits the data packets.
Routing Engine Architecture
The Routing Engine is an Intel-based PCI platform running the JUNOS Internet software,
which Juniper Networks has developed and optimized to handle large numbers of network
interfaces and routes. The software consists of a set of system processes running in protected
memory modules on top of an independent operating system. The JUNOS kernel supports
JUNOS system processes, which handle system management processes, routing protocols,
and control functions (see Figure 13).
which Juniper Networks has developed and optimized to handle large numbers of network
interfaces and routes. The software consists of a set of system processes running in protected
memory modules on top of an independent operating system. The JUNOS kernel supports
JUNOS system processes, which handle system management processes, routing protocols,
and control functions (see Figure 13).
The Routing Engine has a dedicated 100-Mbps internal connection to the Packet Forwarding
Engine.
Engine.