Sunday, July 13, 2014

L3VPN basics and Pros and cons in MPLS senerio.

Hi Friends,

Today i will try my best to clear some of your doubts about L3VPN.

What is L3VPN--  It is a VPN model, the service provider routers carry the customer data across the network, but they also participate in the customer routing. In other words, the service provider routers peer directly with the customer routers at Layer 3. The result is that one routing protocol neighborship or adjacency exists between the customer and the service provider router.

Senerio before MPLS -L3VPN model could be achieved by creating the IP routing peering between the customer and service provider routers. The VPN model also requires privateness or isolation between the different customers. You can achieve this by configuring packet filters (access lists) to control the data to and from the customer routers.
      Before MPLS came into being, the L2VPN  was deployed much more commonly than the L3VPN. The L3VPN model demanded a lot from provisioning because adding one customer site demanded many configuration changes at many sites.
 

Senerio after MPLS- The privateness in MPLS VPN networks is achieved by using the concept of virtual routing/ forwarding (VRF) and the fact that the data is forwarded in the backbone as labeled packets. The VRFs ensure that the routing information from the different customers is kept separate.



 Advantage of L3VPN model-benefit for the service provider is that it only needs to provision the link between the PE and CE routers. With the L2VPN model, the service provider needs to provision the links or virtual circuits between the sites.


Disadvantage of L3VPN model-
1. The customer must share the routing responsibility with the service provider.
2. The edge devices of the service provider have an added burden.
3.The service provider is responsible for the scalability and routing convergence of the customer networks because the PE routers must be able to carry all the routes of the many customers while providing timely routing convergence.

Br//

Rishabh Mittal.

 

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