Using Route Maps To Redistribute Routing Information - Cisco Catalyst 3750 Software Configuration Manual

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:
Command
Step 1 configure terminal
Step 2
ip default-network network number
Step 3
end
Step 4 show ip route
Step 5 copy running-config startup-config
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 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.
You can also identify route-map statements as permit or deny. If the statement is marked as a deny, the
packets meeting the match criteria are sent back through the normal forwarding channels
(destination-based routing). If the statement is marked as permit, set clauses are applied to packets
meeting the match criteria. Packets that do not meet the match criteria are forwarded through the normal
routing channel.
Catalyst 3750 Metro Switch Software Configuration Guide
28-90
Purpose
Enter global configuration mode.
Specify a default network.
Return to privileged EXEC mode.
Display the selected default route in the gateway of last resort
display.
(Optional) Save your entries in the configuration file.
Chapter 28 Configuring IP Unicast Routing
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