Basic IP Routing Configuration
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17 BASIC IP ROUTING
CONFIGURATION
This chapter provides an overview of IP routing and describes the tasks involved in configuring
static IP routing in SmartWare. For a complete description of the IP routing configuration commands
in this chapter, refer to Chapter 15, “Interface Mode”, in the SmartWare
Command Reference Guide
.
This chapter includes the following sections:
•
Introduction
•
Basic IP Routing Configuration Task List
•
Example
17.1 Introduction
IP routing moves information across an internetwork from a source to a destination, typically
passing through one or more intermediate nodes along the way. The primary difference between
routing and bridging is the two different access levels of information that are used to determine how
to transport packets from source to destination; routing occurs at Layer 3 (the network layer), while
bridging occurs at Layer 2 (the link layer) of the OSI reference model. In addition to transporting
packets through an internetwork, routing involves determining optimal paths to a destination.
Routing algorithms use
metrics
, or standards of measurement, to establish these optimal paths and
for initializing and maintaining routing tables that contain all route information.
Routing Tables
The SmartWare routing table stores routes to:
•
directly-attached interfaces or networks,
•
static IP routes, and
•
routes learned dynamically from the Routing Information Protocol (RIP).
In the routing table, next-hop associations specify that a destination can be reached by sending
packets to a next-hop router located on an optimal path to the destination. When the SmartNode
receives an incoming packet, it checks the destination address, and attempts to associate this address
with a next-hop address and outgoing interface. Routing algorithms must converge rapidly — that
is, all routers must agree on optimal routes. When a network event causes routes either to go down
or to become unavailable, routers distribute routing update messages that permeate networks,
causing recalculation of optimal routes that are eventually agreed upon by all routers. Routing
algorithms that converge slowly can cause routing loops or network outages. Many algorithms can
quickly select next-best paths and adapt to changes in network topology.
Static Routing
Static routing involves packet forwarding on the basis of static routes configured by the system
administrator. Static routes work well in environments where network traffic is relatively predictable
and where the network topology is relatively simple. In contrast, dynamic routing algorithms adjust
to changing network circumstances by analyzing incoming routing update messages. RIP uses
dynamic routing algorithms.
Software Configuration Guide, Revision 1.03
Summary of Contents for SmartWare R2.00
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