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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter 31 Configuring IP Unicast Routing
Configuring Protocol-Independent Features
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.
Using Route Maps to Redistribute 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 conditionally control the redistribution of routes between routing domains by defining route
maps between the two domains. The match and set route-map configuration commands define the
condition portion of a route map. The match command specifies that a criterion must be matched; the
set command specifies an action to be taken if the routing update meets the conditions defined by the
match command. 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 16 in the following section is optional, you must enter at least one
match route-map configuration command and one set route-map configuration command. For complete
syntax information for the command, refer to the Cisco IOS IP and IP Routing Command Reference for
Release 12.1.
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.
Command
Purpose