The other thing that I want to discuss in this chapter is the difference between the Control plane and the Forwarding plane.

Juniper has the following 2 different planes:

In this part, I am just going to give you a simple idea about this, but we will go more in details about it in upcoming parts of this chapter. For now, just be aware that Juniper has those 2 different planes. Let’s start talking about the control plane.

In the control plane you have the Routing Engine. The Routing Engine is mainly focusing on the routing tasks, it collects all routings and put them in the Routing Table (RT) then give a copy of the active routes to the Forwarding Table (FT) inside the routing engine. Also on this plane, it is responsible to give you access to the router such as the command line. Of course, there are more functions that happen on the control plane, but for now I will not go more in detail (will be in the upcoming points in this chapter).

Now let’s talk about the Forwarding plane. There it is responsible for all transit traffic, meaning the traffic that are coming from one side and going to another side such as traffic coming from the LAN passing through the juniper router and going to the internet.

I told you previously that in the control plane there is the routing table which has all active and inactive routes, and it will send a copy of the active routes to the primary forwarding table in the Routing engine (RE). Once this is done, then the primary forwarding table will send a complete copy of the routing entries to the Forwarding table inside the Packet Forwarding Engineer in the forwarding plan. Over there, all routing decisions is made for the transit traffic that is passing via the Juniper router.

If you are lost, don’t worry because I am going to go more in details about it in the upcoming points in this chapter.