The first place to tackle SDN In the WAN

22.01.2015
Disruptive innovation in infrastructure is on the rise, and nowhere is that more evident than in the Software Defined Networking movement. But while much of the SDN discussion has focused on the data center, the better initial use case might be in the wide area network. One advocate of that approach is Michael Elmore, IT Senior Director of the Enterprise Network Engineering Infrastructure Group at Cigna, a global health service company headquartered in Bloomfield, Connecticut. Michael is also on the board of Open Network Users Group (ONUG). Network World Editor in Chief John Dix asked Elmore to participate in an email-based Q&A to explore the promise of Software Defined WANS.

The members of the Open Network User Group that you are a member of have voted the WAN as the top use case for SDN twice in a row now. Why do you think that is

Consider this quote from a Wall Street firm at the recent Open Networking User Group meeting in New York: "Although much of Wall Street has focused on the 'sexy' datacenter aspect of SDN, interest in software-defined WAN has increased meaningfully and we believe SD-WAN could experience more rapid adoption than datacenter overlay technologies. SD-WAN can dramatically reduce the cost of WAN deployments by enabling cheaper bit rates in both CAPEX and OPEX (i.e., less cost for the same bandwidth or more bandwidth for the same cost as compared to MPLS) and less overprovisioning for the same SLAs."

What's more, the WAN tends to be more discreet in terms of organizational teams and the technology stack itself, meaning organizations can move faster to embrace SD-WANs. So, if you're interested in building a WAN that is better, faster and cheaper, there are some key issues to consider.

What WAN issues today would encourage a company to start exploring SD-WAN options

There are many challenges and limitations with the predominant MPLS-based layer 3 VPN service offerings that have become the standard connectivity solution for many Fortune 500 companies over the past 15 years. Although these solutions have served the enterprise well in a time of limited options, the market is opening up and ripe for transformation.

Previous attempts to scale VPN overlays have not found their way to mainstream, due to protocol scalability limitations and the sheer configuration complexity required for a reasonably sized enterprise network. As more and more critical business applications -- such as voice, contact center and storage applications -- converge to an IP transport, a high-performing and ultra-resilient (self-healing) IP WAN fabric will become essential to the business.

Let's examine the WAN challenges today:

Cost:

Scale:

Service quality:      

Security:  

Visibility:

Agility/flexibility:     

So if those are the WAN challenges today, what is the SDN promise

In short, the SD-WAN can enable customers to take back control from service providers, while creating new market opportunities for those service providers.

If customers could create SD-WANs that separate the underlying transport from a software-based, overlay control plane on controller(s) owned by the customer, it would empower them, among other things, to centrally manage security policies and make

application-based routing decisions dynamically and based on application performance criteria -- all independent of the underlying transport.

The underlay just becomes a set of common IP circuits with next hop reachability. This opens the door for customers to go direct to the local market (LEC, MSOs, etc.) to procure more cost-effective bandwidth with the right mix of transport technologies and SLAs required for the business, without compromising or fragmenting the logical routing topology.

Consider a company that has business process outsourcing, business-to-business, internal, or other WAN constructs, which increase complexity and cost. What if a network administrator could build an underlying network with various transport providers and glue the transport together with a unified overlay providing centralized policy management via a controller to create logical segmentation for multi-tenancy Essentially, this would drive up the efficiency rate, creating a more cost-effective network.

The benefits become exponential when you couple an SD-WAN strategy with converging and centralizing/regionalizing services such as SIP voice, IP Contact Center and other services, which are often distributed and reside on edge CPE today (DSPs, SRST).

Let's dive into how each of the previous problem statements gets addressed with SD-WAN.

Cost: 

Scale:           

Service quality:      

Security:      

Visibility:      

Agility/flexibility:

How close are we to realizing this nirvana vision

The technology is very close, both from the traditional equipment suppliers and early stage start-ups. However, vendors are taking different approaches for prioritizing the features they will implement, and in developing their product roadmaps.   Many of the

approaches will overlay Internet transport in the long run. The timing seems appropriate, especially given the maturation that has taken place with real-time services and codecs moving from narrow band to wide band, driving up the tolerance for Internet performance characteristics.

So, if an organization likes the sounds of SD-WANs, what kinds of questions should they be mulling to see if it is good option for them 

Are there remaining concerns or potential speed bumps that enterprise customers should consider

The SD-WAN approach could also lead to carrier proliferation. How many carriers are too many One side of the spectrum will suggest the more carriers, the better unit pricing. However, the resources required to manage a certain number of carriers may ultimately be unsustainable, hitting a diminishing marginal utility effect.

There is also the question of open versus closed. Many of these solutions will be shrink wrapped and closed alternatives, so if you desire openness and the desire to integrate multiple suppliers across a single overlay, you may need to wait.

It's clear that the time is now for enterprises to perform a market scan and develop a detailed set of problem statements to address. As a potential SD-WAN consumer here in the early stages of this emerging market, you have an opportunity to help guide development efforts and prioritization with the core suppliers.

(www.networkworld.com)

John Dix