Difference between L2 MPLS and L3 MPLS

[vdadlaney]

Hi, could someone explain the difference between L2 MPLS and L3 MPLS and the relationship between a VRF and a VPN For eg: Is there a One to one mapping between VRF and VPN and what happens when you need to have your one site access different services from each other. Thank you

Regards,

Vikram

[sultan-shaikh]

Hi,

As the name says, the difference is in L2 and L3, the basic difference being in L3 VPNs the routing for the customers is done by the Service Provider who maintains a VRF per customer or per L3VPN.

In case of a L2VPN, the analogy can be like laying an Ethernet cable across the customer locations, where routing will be managed by the customer.

There are a number of standards and drafts abounding on this topic, you can read the drafts by PWE3 and PPVPN working group of IETF for L2VPNs.

RFC 2547bis is the standard for L3VPN.

Here are a few links:

For L2VPN:-

http://dsonline.computer.org/0405/f/w3wirp.htm

For L3VPN:-

http://www.juniper.net/solutions/literature/white_papers/200012.pdf

This should help !!!

sultan...

[vdadlaney]

Hi Sultan,

Thanks for your input on this. I was looking more along the lines of AToM and how to differentiate. I have heard of L2MPLS-VPN and L3-MPLS VPN's and AToM being referenced as L2MPLS. Would it be right to say that basically in AToM the customer manages the routing whereas the service provider provides the physical connectivity. Thanks

[sultan-shaikh]

Yes, you are right,

Any Transport over MPLS-as the name says, enables you to carry any Layer 2 technology across the MPLS backbone, hence the "L2" in the name.

T

here is also another technology by the name of L2.5 VPN doing the rounds, I have implemented it on Juniper, where it is known as VLAN-TCC, it is same as L2VPN, the difference being that you can have disparate, L2 technologies-say Frame Relay and Ethernet, at either ends of the VPN.

Cheers,

sultan...