System Architecture Description For T Series Routers; Routing Engine Functions For T Series Routers; Figure 1: Router Architecture - Juniper Core Router T Series Hardware Manual

System Architecture Description for T Series Routers

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Routing Engine Functions for T Series Routers

Copyright © 2018, Juniper Networks, Inc.
The T Series Core Routers have two main architectural components:
Routing Engine—One or more Routing Engines provide Layer 3 routing services and
network management.
Packet Forwarding Engines—These high-performance, ASIC-based components provide
Layer 2 and Layer 3 packet switching, route lookups, and packet forwarding.
The Routing Engines and the Packet Forwarding Engines perform their primary tasks
independently, although they constantly communicate through multiple 100 millions of
packets per second (Mbps) links. This arrangement streamlines forwarding and routing
control and runs Internet-scale backbone networks at high speeds.
shows the relationship between the Routing Engine and the Packet Forwarding Engines.

Figure 1: Router Architecture

Routing Engine Functions for T Series Routers on page 5
Packet Forwarding Engine Architecture for T Series Routers on page 7
The Routing Engine handles all routing protocol processes, as well as the software
processes that control the router's interfaces, the chassis components, system
management, and user access to the router. The routing and software processes run on
top of a kernel that interacts with the Packet Forwarding Engine.
The Routing Engine constructs and maintains one or more routing tables (see
Figure 2 on page 6). From the routing tables, the Routing Engine derives a table of active
routes, called the forwarding table, which is then copied into the Packet Forwarding
Engine. The design of the ASICs allow the forwarding table in the Packet Forwarding
Engine to be updated without interrupting forwarding performance.
Chapter 1: System Overview and Architecture
Figure 1 on page 5
5