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
Routing Engine Functions
The Routing Engine handles all routing protocolprocesses, as well as
the software processes that control the router’s inte rfaces, the chassis
components, system management, and user accessto the router. These
routing and software processes run on top of a kernel that interacts with the
Packet ForwardingEngine. For more informationabout the processes, see
Routing Engine Software Components on page 43.
The Routing Engine includes the followingfunctions and features:
Processing of routing protocolpackets—The Routing Engine handles all
packets that concernrouting protocols, freeing the PacketForwarding Engine
to handle only packetsthat represent Internet traffic.
Software modularity—Because each software process is devoted to a different
function and uses a separate process 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 flexibil ity for advertising,
filtering, and modifying routes. Routing policies areset according to route
parameters(for example, prefix, prefixlengths, and Border Gateway Protocol
[BGP] attributes).
Scalability—The JUNOS routingtables have been designed to hold all the
routes in currentnetworks with ample capacity for expansion. Additionally,t he
54 Routing Engine Architecture