Juniper G10 CMTS, Hardware Manual

Page: 74 / 210

JUNOSg Internet Software Overview
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JUNOSg 3.0 G10 CMTS Hardware Guide 58
Routing Engine Software Components
The Routing Engine software consists of several software processes that control router
functionality and a kernel that provides the communication among all the processes. This
section describes each of the Routing Engine software components:
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Routing Protocol Process on page 58
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Interface Process on page 60
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SNMP and MIB II Processes on page 60
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Management Process on page 60
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Routing Engine Kernel on page 60
Routing Protocol Process
The software routing protocol process controls the routing protocols that run on the CMTS.
The routing protocol process starts all configured routing protocols and handles all routing
messages. It maintains one routing table and consolidates the routing information learned
from all routing protocols into this common table. From this routing information, the routing
protocol process determines the active routes to network destinations and installs these
routes into the Routing Engine’s forwarding table. Finally, the routing protocol process
implements routing policy, which allows you to control the routing information that is
transferred between the routing protocols and the routing table. Using routing policy, you can
filter routing information so that only some of it is transferred, and you also can set
properties associated with the routes.
For complete information about the routing protocol process, including routing protocols,
routing and forwarding tables, routing policy, and interfaces, see the JUNOSg software
configuration guides.
Routing Protocols
The JUNOSg Internet software implements full IP routing functionality, providing support for
IP Version 4 (IPv4). The routing protocols are fully interoperable with existing IP routing
protocols, and provide the scale and control necessary for the Internet core. The software
provides support for the following routing and traffic engineering protocols:
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OSPF—Open Shortest Path First, Version 2, is an IGP that was developed for IP networks
by the Internet Engineering Task Force (IETF). OSPF is a link-state protocol that makes
routing decisions based on the SPF algorithm.
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RIP—Routing Information Protocol, Version 2, is an IGP for IP networks based on the
Bellman-Ford algorithm. RIP is a distance-vector protocol. The JUNOSg RIP software is
compatible with RIP Version 1.
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ICMP—Internet Control Message Protocol router discovery allows hosts to discover the
addresses of operational routers on the subnet.