MPLS L3 VPN

1. The problem with VRFs is that you have to create them everywhere. When our goal is to have connectivity between CE1 and CE3 then we will have to add a VRF on the PE1, P and PE2 router. Also, all the service provider routes will have to participate with routing.

2. We will use MP-BGP between the PE routers so that they can share information from the VRFs without run VRF at P routers.

The PE2 router will learn 192.168.1.0 /24 from the PE1 router but it has no clue to what customer it will belong. There is no way to differentiate if something belongs to customer A or B.

RD (Route Distinguisher)
To fix this issue, we will use a RD (Route Distinguisher). We will add something to the prefix of the customer so that it will become unique: The RD and the prefix combined is what we call a VPNv4 route. We now have a method to differentiate between the different prefixes of our customers.

RT (Route Target)
We use something called a RT (Route Target) to decide in which VRF we import and export VPNv4 routes.

Steps to Configure MPLS L3 VPN