This chapter describes how to configure RIP. For a complete description
of the RIP commands that appear in this chapter, refer to Chapter
8, “RIP Commands.” To locate documentation of other commands
that appear in this chapter, you can search online at www.cisco.com.
The Routing Information Protocol (RIP) is a relatively old, but still
commonly used, interior gateway protocol (IGP) that was created for use in
small, homogeneous networks. It is a classical distance-vector routing protocol.
RIP is documented in RFC 1058.
RIP uses broadcast User Datagram Protocol (UDP) data packets to exchange
routing information. The Cisco IOS software sends routing information updates every 30 seconds;
this process is termed advertising. If a router does
not receive an update from another router for 180seconds or more, it marks
the routes served by the nonupdating router as being unusable. If there is
still no update after 240 seconds, the router removes all routing table entries
for the nonupdating router.
The metric that RIP uses to rate the value of different routes is hop
count. The hop count is the number of routers that can be traversed
in a route. A directly connected network has a metric of zero; an unreachable
network has a metric of 16. This small range of metrics makes RIP an unsuitable
routing protocol for large networks.
If the router has a default network path, RIP advertises a route that
links the router to the pseudonetwork 0.0.0.0. The network 0.0.0.0 does not
exist; RIP treats 0.0.0.0 as a network to implement the default routing feature.
The Cisco IOS software will advertise the default network if a default was
learned by RIP, or if the router has a gateway of last resort and RIP is configured
with a default metric.
RIP sends updates to the interfaces in the specified networks. If an
interface's network is not specified, it will not be advertised in any RIP
Cisco's implementation of RIP Version 2 supports plain text and MD5
authentication, route summarization, classless interdomain routing (CIDR), and variable-length
subnet masks (VLSMs).
For protocol-independent features, which also apply to RIP, see Chapter 19, “Configuring IP Routing Protocol-Independent
To configure RIP, complete the tasks in the following sections. You
must enable RIP. The remaining tasks are optional.
Allow Unicast Updates for RIP
Apply Offsets to Routing Metrics
Specify a RIP Version
Enable RIP Authentication
Disable Route Summarization
Run IGRP and RIP Concurrently
Disable the Validation of Source IP Addresses
Enable or Disable Split Horizon
Configure Interpacket Delay
For information about the following topics, see Chapter
19, “Configuring IP Routing Protocol-Independent Features.”