Administrator Guide

Generating a Default Route
Traffic is forwarded to the default route when the traffic’s network is not explicitly listed in the routing table.
Default routes are not enabled in RIP unless specified. Use the default-information originate command in ROUTER RIP mode
to generate a default route into RIP. Default routes received in RIP updates from other routes are advertised if you configure the
default-information originate command.
• Specify the generation of a default route in RIP.
ROUTER RIP mode
default-information originate [always] [metric value] [route-map route-map-name]
• always: Enter the keyword always to always generate a default route.
• value The range is from 1 to 16.
• route-map-name: The name of a configured route map.
To confirm that the default route configuration is completed, use the show config command in ROUTER RIP mode.
Summarize Routes
Routes in the RIPv2 routing table are summarized by default, thus reducing the size of the routing table and improving routing efficiency in
large networks.
By default, the autosummary command in ROUTER RIP mode is enabled and summarizes RIP routes up to the classful network
boundary.
If you must perform routing between discontiguous subnets, disable automatic summarization. With automatic route summarization
disabled, subnets are advertised.
The autosummary command requires no other configuration commands. To disable automatic route summarization, enter no
autosummary in ROUTER RIP mode.
NOTE:
If you enable the ip split-horizon command on an interface, the system does not advertise the summarized
address.
Controlling Route Metrics
As a distance-vector protocol, RIP uses hop counts to determine the best route, but sometimes the shortest hop count is a route over the
lowest-speed link.
To manipulate RIP routes so that the routing protocol prefers a different route, manipulate the route by using the offset command.
Exercise caution when applying an offset command to routers on a broadcast network, as the router using the offset command is
modifying RIP advertisements before sending out those advertisements.
The distance command also allows you to manipulate route metrics. To assign different weights to routes so that the ones with the
lower weight or administrative distance assigned are preferred, use the distance command.
To set route matrixes, use the following commands.
• Apply a weight to all routes or a specific route and ACL.
ROUTER RIP mode
distance weight [ip-address mask [access-list-name]]
Configure the following parameters:
• weight: the range is from 1 to 255. The default is 120.
• ip-address mask: the IP address in dotted decimal format (A.B.C.D), and the mask in slash format (/x).
• access-list-name: the name of a configured IP ACL.
• Apply an additional number to the incoming or outgoing route metrics.
ROUTER RIP mode
offset-list access-list-name {in | out} offset [interface]
Configure the following parameters:
• prefix-list-name: the name of an established Prefix list to determine which incoming routes are modified
• offset: the range is from 0 to 16.
• interface: the type, slot, and number of an interface.
To view the configuration changes, use the show config command in ROUTER RIP mode.
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Routing Information Protocol (RIP)