Routing Using RIP version 2 en Cisco(Part 1)

In this article we will try to expose a simple way to configure Routing in an environment of Cisco technologies RIP.

It is necessary that certain knowledge management Cisco simulator devices and networks have Packet Tracer.

The easiest way to set is dynamic routing protocol by using RIP (Routing Information Protocol).
Through this protocol can get routers share information about known networks, so that reach a router learn routes to networks that are not directly connected to it.
To make the protocol settings must decide how interfaces (NICs) It is to communicate with others routers, and the version of the protocol to use, usually the 2. These interfaces must contact both routers, and the two have to use the same version. Through these cards the routing information is sent (RIP messages, called updates, with information about the routes to reach remote networks)

Comando network para RIP en Cisco

The base configuration Cisco RIP protocol is in the network command.
This command serves two purposes:

• RIP inform about what interfaces involved in the sending and receiving routing updates.
• RIP ask others to announce the existence of routers network.

The best way to see it is by example, made with the Packet Tracer:

In the diagram we have three routers (R1, R2 and R3) interconnected as can be seen, via serial connections (red wires) and a private network switches each.
RIP configuration in R2 is:

R2>enable
R2#configure terminal
R2(config)#router rip
R2(config-router)#version 2
R2(config-router)#network 200.1.1.0
R2(config-router)#network 200.2.2.0
R2(config-router)#network 192.168.20.0

By setting network 200.1.1.0 we are indicating that the interfaces on that network (Serial Connection) used for sending and receiving routing updates. Besides that this network will be announced to the rest of possible routers present (in this case the notified R1, as it is in the same network and already knows, however yes that notifies R3). For network 200.2.2.0 It is similar.
With the ruling network 192.168.20.0 we are indicating that the network is notified to the other routers (R1 and R3). Apparently, by said network interface routing updates that are not needed are sent, for there is no router connected there. You can avoid this by setting the interface as passive.
For that, in the configuration file as example we:

R2(config-router)#passive-interface f0/0

Similarly the other two routers are configured. They have not set passive-interface, to see the difference when simulation; it can be seen how RIP packets move through the interfaces, except those established as passive.
In the sample file, al abrir Packet Tracer, if we choose the simulation option and look over the packages, observe how RIP move as expected, for interfaces that were not established as passive.

In this picture we see that RIP updates are not sent to the private network of R2, however yes they are in R3.

Network expansion

One advantage of using a protocol such as RIP is the time to make changes to the network.
Eg, if you add a new network in R1, simply configure R1, It is not necessary to configure all routers (which it would be necessary in the case of static routing)
As seen in Figure:

Adding network 192.168.40.0, you only need to enter a command in R1, RIP will handle the rest announce that network:

R1(config-router)#network 192.168.40.0

Or restart or anything, The change is automatic and the new network quickly spread to others.
To make checks you can ping from equipment without errors. It should take a look at the routing tables for each router:

R2#show ip route

To understand the behavior of the network command should study the case of a segmented network into subnets, what you can do next link .

Download here the sample file (created with Packet Tracer 6)

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