So lets first talk about problem with building MPLS Layer 3 VPNs. Basically the problem people usually encounter with MPLS VPNs is that it's basically collection of many many technologies working together which makes it look alike complex technology. But no matter how much complex something looks alike, it's just collection of different technologies/pieces working together. And as long as you can break complex things into pieces, it makes it easy.
So lets try to list down different technologies you need to master in prior in order to make MPLS Layer 3 VPN work:
> Layer 2 Technologies ( Ethernet, Switching & Bridging, PPP, Frame-Relay)
> IGPs (RIP, EIGRP, OSPF)
> EGP (BGP)
> Cisco Express Forwarding (CEF)
> MPLS Label Distribution Protocols (TDP, LDP, BGP, RSVP)
> Multi Protocol BGP (MPBGP)
> Basics of Virtualization (Concept)
So you see there are many technologies working together. And most importantly you need to master all this stuff before you start working on MPLS layer 3 VPNs.
On the flip side, if you really know and understand all technologies mentioned above, The MPLS Layer 3 VPNs is nothing but making all these technologies work together.
In next post I'll start with Building the Service Provider Core network to get it ready for running MPLS VPNn. Below is the topology we will be using. Stay tuned.....