Juniper Networks M5, M10 manual System Architecture Overview, Packet Forwarding Engine Architecture

Chapter 4

System Architecture Overview

The router architecture consists of two major components:

•Packet Forwarding Engine—Performs Layer 2 and Layer 3 packet switching, route lookups, and packet forwarding.

•Routing Engine—Provides Layer 3 routing services and network management.

The Packet Forwarding Engine and the Routing Engine perform independently but communicate constantly through a 100-Mbps internal link. This arrangement provides streamlined forwarding and routing control and the ability to run Internet-scale networks at high speeds. Figure 12 illustrates the relationship between the Packet Forwarding Engine and the Routing Engine.

Figure 12: System Architecture

Packets

in

Routing Engine

100-Mbps link

Packet Forwarding	Packets
Engine	out

1244

For a discussion of the architectural components, see the following sections:

•

•

Packet Forwarding Engine Architecture on page 29

Routing Engine Architecture on page 31

Packet Forwarding Engine Architecture

The Packet Forwarding Engine performs Layer 2 and Layer 3 packet switching. It can forward up to 40 for all packet sizes. The aggregate throughput for the router is 6.4 gigabits per second (Gbps), full duplex. The Packet Forwarding Engine is implemented in application-specific integrated circuits (ASICs). It uses a centralized route lookup engine and shared memory.

The Packet Forwarding Engine architecture includes the following components:

System Architecture Overview 29