We are starting with Routers without any configuration, so the first step is to assign IP addresses and enable interfaces on the routers and on the switch.
Here is the network table what are we gonna use:
PC 192.168.0.1
Router1 G0/1-192.168.0.2 G0/0-172.16.0.2
Router2 G0/0-10.0.0.3
Router3 G0/0-10.0.0.2
Router0 G0/0-10.0.0.1 G0/1-172.16.0.1
When all the interfaces are UP, and the PC is configured by IP address in the range, we can try to ping the router1 and then the router2 to make sure that routing is not enabled on router1.
Lest walk trough the pinging steps and take a look at the behavior of the ICMP(ping):
First, when we try to ping the 192.168.0.1 (Router1) interface, the ping succeeds without any configuration, it is because of its a connected interface with the same IP range.
Next, try to ping the 172.16.0.2 – It is also replying, the ping succeeds because the interface is on the same router (router1) and he knows the route to the 192.168.0.2 (PC).
NOTE: Routers can route without any configuration on connected interfaces!
Next is to ping the 172.16.0.1 (Router0) – Notice the behavior that the ping reply is request timed out – This is because of the router1 knows the destination and he sends the frame but the reouter0 doesn’t know where shall he respond to the ping, so the frame gets dropped.
The last ping is going to 10.0.0.3 (Router2) – Here we are getting the Destination host unreachable reply from Router1 – He doesn’t know about network 10.0.0.0
Now the testing is done, and we can see that we should implement a routing protocol.
Start with RIPv2
Commands what will be used for implementation:
router rip – Starting up a rip protocol
version 2 – Enabling ripv2 functionality
network “x.x.x.x” – Adding a network for routing
no auto-summary – Enabling discontinuous subnet mask ( by default rip summarizes the networks)
passive-interface “interface” – Turning off the interface from propagating rip messages
default-information originate – Enabling the router to spread his default gateway information
Let’s Begin with router1 – we are configuring all the commands from the previous list, also the passive-interface command because we do not need to send out RIP data on G0/1 – to the PC; After the configuration, we can check if it succeeds with “show ip protocols” command, it gives the next result:
We have to follow the same configuration on all the other routers.
After the configuration is done they will advertise the routes to each other without any additional configuration.
To prove that the connection is live we can now ping the 10.0.0.0 network devices from the PC0.
Here is the example picture of ping request:
If we add additional networks to the router’s interfaces, we have to add them to the RIP protocol as well, with the network command, to make sure they will be propagated to other routers.
Be aware that the RIPv2 by default will summarize the networks to the classful boundary like the RIP, so to prevent it and allow VLSM mask’s we have to use no auto-summary command.
The current network would work with summarization because we have used stateful addresses.
Note that rip is supporting to maximum 15 hops !
