Antonio Sanchez Monge - MPLS in the SDN Era: Interoperable Scenarios to Make Networks Scale to New Services

In the early 2010s, some people claimed that Softwared-Defined Netwroking (SDN), specifically, OpenFlow would replace MPLS. However, after realizing the many challenges of the first OpenFlow version, SDN was redefined into a paradigm (SDN 2.0) that shares many of the principles that have made MPLS a very successful service provider technology for decades.

Looking at SDN and MPLS as competing technologies is fundamentally wrong. MPLS is a key SDN enabler. This statement holds particularly true if you look at MPLS as an architectural paradigm (not as an encapsulation). In a nutshell, this is the MPLS model:

• Decoupling control plane from forwarding plane.

• Decoupling service from transport.

• Decoupling overlay from underlay.

• Layered architecture with a feature-rich edge and a fast transport core. This approach can be applied to the WAN, to data centers, and so on.

• Building overlay networks at the edge in order to support multitenancy and multiservice .

• Minimizing the forwarding state on the core.

• Advanced packet steering by either signaling forwarding paths and/or by stacking instructions on packet headers.

It is hard to imagine a scalable network that does not follow these principles. The implementation details (and the actual encapsulation is one of these details) are secondary. For example, this book considers Ethernet VPN (EVPN) with Virtual eXtensible LAN (VXLAN) transport as a genuine MPLS technology. Even if it does not make use of MPLS labels, this solution is truly based on the MPLS paradigm. Looking at the details, VXLAN does not implement instruction stacking and it uses an IP-based encapsulation whose header overhead is 10 times bigger than that of MPLS.

On the other hand, there is a fast-growing MPLS trend at large-scale data centers, especially for cloud providers. New data center solutions use the Border Gateway Protocol (BGP) and MPLS technologies in a similar way to what WAN service providers have done for decades. This trend not only includes the MPLS paradigm, but more and more, the MPLS encapsulation, too.

One of the proofs that MPLS is more relevant in the SDN era than ever is the exploding amount and variety of MPLS features that networking vendors are developing to meet the requirements of a fast-changing market. This book tries to reflect this reality by including technologies and use cases that are in their earliest life stage.

MPLS is a flexible technology that is not complex, per se. As any modular technology, it can become as complex as you want (or rather, as complex as the requirements are).

This book is written so that you can read it in a linear fashion, from its first page to the last one, which is the approach that we recommend. However, if you are only interested in certain chapters, the following list alerts you to the interchapter dependencies. For example, the dependencies for if youd like.

lays the foundation for the rest of the book by introducing basic MPLS and SDN concepts and by providing a static LSP example. There are no chapter dependencies.