Don't allow the term to confuse you, Overlay Networks are nothing new and have evolved over time, its just a matter of understanding the operation, today MPLS is the most prominent and the advantages are clear!
There have been two primary VPN models that have been used by Service Providers:
- The overlay model - where the service provider provides emulated leased lines to the customer. The overlay model typically uses the virtual circuits of a Frame Relay or ATM service. The overlay model has advantages such as permitting the duplication of addresses and the isolation of the control and security planes.
- The peer-to-peer model - where the service provider and the customer exchange Layer 3 routing information and the provider relays the data between the customer sites on the optimum path between the sites. Layer 3 MPLS VPNs permit the creation of a peer-to-peer model with many of the advantages of the overlay model, such as the duplication of addresses.
Hi Scott, really make sense your explanation for the term overlay. I was reading your response on the other thread regarding SONET.
And you commented on that link that MPLS is overlay, then i found another post of yours that clears the dark clouds of my understanding for the term overlay.
Thank you so much.
I just hope one day, when CISCO wants you to write a book that you will do the same, stick to the point and clear as a crystal water the explanation.
Because some of the author for Cisco book, they will drive you around in circles before you get the idea. when in fact it is just a very small matter.
anyway i think that's how marketing strategy works.
to the original poster, don't really mean to hijack this post.
But can't find a way to thank Scott except to do this. Thanks again Sir Scott.
well...as much as I respect Scott and everything he had achieved and contributed to so many CCIEs, I have to respectfully disagree with MPLS being an ‘overlay network’ and agree with Anthony Sequeria. It is all about who you peer routing with. Frame-Relay is an overlay network because the provider does not participate in customer routing. MPLS is a ‘peer-to-peer’ model network because the provider Does participate in customer routing.