Networking Experiments: JUNOS Basics

In this post we will look at the basics of JUNOS. We will go through some of the stuff which can be useful in JNCIA exam.

In my topology, I have two routers running JUNOS. Both are directly connected.

Please refer to the link below which explains how to setup JUNOS in GNS3.

http://networknutsnbolts.wordpress.com/2014/10/29/how-to-set-up-juniper-routers-in-gns3-v1-1-with-qemu-and-get-it-working/

Now, let's fire up both the routers. You will notice that it takes good few minutes for Junos to boot up. You will see output as below once it's done.

We can login with the "root" username which will take us to the shell prompt.

At the shell prompt, we need to apply the command "cli" to enable the operational mode.

To go to the configuration mode, apply the command "configure".

Now let's do some basic configuration. We will set the hostname of the router to R1 and create a user named "Test". This user will be a super-user.

We can see that unlike Cisco IOS any config changes do not get applied in the live router configuration. JUNOS saves this changes in something called "candidate configuration". To save this configuration, you will have to "commit" it. Let's try and apply the commit command.

When we apply the commit command, JUNOS checks if there are any issues with the candidate configuration. If there is something wrong/missing, it will generate the error.

The reason we are receiving this error is because initially there is no password for the root user. It is required that you set it otherwise you will not be able to commit any configurations.

Now let's try again to commit the config.

It worked this time. We can come out of the configuration mode by using the "exit" command. It will take us to the operational mode. From there we can view the configuration by applying the "Show configuration" command.