Challenges of SDN in Carrier Networks

Author: Babak Samimi

The OPEX and CAPEX benefits of Software-Defined Networks (SDNs) realized from facilitating the separation of the data, control and management planes (to allow for the orchestration and management of network resources from a central location) are widely accepted. All of us as subscribers stand to benefit from this transformation as this centralized view of network resources will create a manageable, easy-to-automate, flexible platform allowing Carriers to allocate on-demand resources and define services in real-time to keep up with our ever-changing approach of adding and using content from the Internet.  One of the major hurdles to achieving these, however, is that current SDN standards, including the industry favored OpenFlow, have not yet been augmented to specify carrier-grade functionalities.

The road ahead for OpenFlow is not unprecedented. As an industry, we transformed Ethernet from the LAN to being a WAN technology and created Carrier-Grade Ethernet. For OpenFlow to be adopted by carriers, it must also go through a similar transformation of becoming “carrier grade.” To get there, several extensions need to be made to the specification, such as traffic, various types of OAMs (Ethernet, MPLS, BFD), protection switching with fast re-route times under 50 msec, timing and synchronization, L2/L3 VPN, and detailed statistics collection, to name just a few.

In our industry, transformational changes like this make for an exciting chapter ahead that will be marked by significant industry-wide collaboration and an infusion of creativity and innovations to arrive at carrier grade SDN / OpenFlow that will go live into carrier networks worldwide.SDN Evolving

Here, however, is the dilemma: there is tremendous interest and pent-up demand to start this network transformation, though clearly the ecosystem and the supply chain are not in place. How do we minimize risk in R&D investments made in an environment where changes will emerge as standards solidify while enabling the industry to innovate? Given that the end goal is to enable a software controlled network, we should start with flexible and programmable data path hardware architectures that can be upgraded in field via software. This strategy will allow carriers to start system deployments before the standard is finalized, and to add new functionality through software upgrades as requirements and implementation models inevitably evolve.

In my next post, let’s take a look at MPLS-TP OAM and the new extensions needed to OpenFlow as we pave the way to carrier grade SDNs.

This post was also published on SDN Central.

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