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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter 22 Configuring IP Unicast Routing
Configuring Protocol-Independent Features
Beginning in privileged EXEC mode, follow these steps to define a static route to a network as the static
default route:
Use the no ip default-network network number global configuration command to remove the route.
When default information is passed through a dynamic routing protocol, no further configuration is
required. The system periodically scans its routing table to choose the optimal default network as its
default route. In IGRP networks, there might be several candidate networks for the system default. Cisco
routers use administrative distance and metric information to determine the default route or the gateway
of last resort.
If dynamic default information is not being passed to the system, candidates for the default route are
specified with the ip default-network global configuration command. If this network appears in the
routing table from any source, it is flagged as a possible choice for the default route. If the router has no
interface on the default network, but does have a path to it, the network is considered as a possible
candidate, and the gateway to the best default path becomes the gateway of last resort.
Redistributing Routing Information
The switch can run multiple routing protocols simultaneously, and it can redistribute information from
one routing protocol to another. For example, you can instruct the switch to readvertise IGRP-derived
routes by using RIP or to readvertise static routes by using IGRP. Redistributing information from one
routing protocol to another applies to all supported IP-based routing protocols.
You can also conditionally control the redistribution of routes between routing domains by defining a
method known as route maps between the two domains. Although redistribution is a
protocol-independent feature, some of the match and set route-map configuration commands are
specific to a particular protocol.
One or more match commands and one or more set commands follow a route-map command. If there
are no match commands, everything matches. If there are no set commands, nothing is done, other than
the match. Therefore, you need at least one match or set command.
Note
Although each of Steps 3 through 14 in the following section is optional, you must enter at least one
match route-map configuration command and one set route-map configuration command.
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
ip default-network network number
Specify a default network.
Step 3
end
Return to privileged EXEC mode.
Step 4
show ip route
Display the selected default route in the gateway of last resort
display.
Step 5
copy running-config startup-config
(Optional) Save your entries in the configuration file.
