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M160 Internet Router Hardware Guide
Figure 24: Routing Engine Architecture
JUNOS
software
System
management
processes
Routing
protocols
Control
functions
System processes
Operating system
Kernel
Intel-based PCI platform
1164
Routin g Engine Functions
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. These
routing and software processes run on top of a kernel that interacts with the
Packet Forwarding Engine. For more information about the processes, see
Routing Engine Software Components on page 43.
The Routing Engine includes the following functions and features:
Processing of routing protocol packets—The Routing Engine handles all
packets that concern routing protocols, freeing the Packet Forwarding Engine
to handle only packets that represent Internet traffic.
Software modularity—Because each software process is devoted to a different
function and uses a separate pro cess space, the failure of one process has little
or no effect on the others.
In-depth Internet functionality—Each routing protocol is implemented with a
complete set of Internet features and provides full flexibility for advertising,
filtering, and modifying routes. Routing policies are set according to route
parameters (for example, prefix, prefix lengths, and Border Gateway Protocol
[BGP] attributes).
Scalability—The JUNOS routing tables have been designed to hold all the
routes in current networks with ample capacity for expansion. Additionally, the
54 Routing Engine Architecture