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Catalyst 3560 Switch Software Configuration Guide
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Chapter 36 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 set 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. 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
enhanced packet filters or 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 A route map with no set route-map configuration commands is sent to the CPU, which causes high CPU
utilization.
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.