FTOS Configuration Guide for the C-Series - Force10 Networks

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 the
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 command autosummary requires no other configuration commands. To disable automatic route
summarization, in the ROUTER RIP mode, enter no autosummary.
Note: If the ip split-horizon command is enabled on an interface, then the system does not advertise
the summarized address.
Control 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, you must 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. Use the command to assign different
weights to routes so that the ones with the lower weight or administrative distance assigned are preferred.
To set route metrics, use either of the following commands in the ROUTER RIP mode:
Command Syntax Command Mode Purpose
distance weight [ip-address mask
[access-list-name]]
offset access-list-name {in | out} offset
[interface]
ROUTER RIP Apply a weight to all routes or a specific route
and ACL. Configure the following parameters:
• weight range: 1 to 255 (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: name of a configured IP
ACL.
ROUTER RIP Apply an additional number to the incoming or
outgoing route metrics. Configure the
following parameters:
• access-list-name: the name of a configured
IP ACL
• offset range: 0 to 16.
• interface: the type, slot, and number of an
interface.
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