In this post, I’m going to explain how we can use an SDN controller to provision traffic-engineered MPLS LSPs between PE nodes situated in different traffic-engineering domains.
The SDN controller that we’re going to use is NorthStar from Juniper Networks running version 3.0. For more information regarding NorthStar check here. There is also a great Day One book available: NorthStar Controller Up and Running.
Typically, in order to provision traffic-engineered MPLS LSPs between PE nodes, it is necessary for the PEs to be situated in a common TE domain. There are some exceptions to this such as inter-domain LSP or LSP stitching. However, these options are limited and do not support end-to-end traffic-engineering as the ingress PE does not have a complete traffic-engineering view. I personally haven’t seen many deployments utilising these features.
So, what’s the use case? Many service providers and network operators are using RSVP to signal traffic-engineered LSPs in order to control how traffic flows through their environments. There are many reasons for doing this, such as steering certain types of traffic via optimal paths or achieving better utilisation of network bandwidth. With many RSVP deployments, you will see RSVP used in the core of the network with islands of LDP at the edge. You will often find that the IGP adopts a similar architecture. Meaning separate traffic engineering domains. But what if I want to signal a traffic-engineered LSP between PEs located in different domains?