Last week I started my SDN reflections on the London Gartner Data Center Conference, and I found I had quite a lot to discuss.

Last week I covered:

• Do we need SDN?
• SDN and the Gartner Hype Cycle
• SDN Deployment Models

So here is the concluding part. This week I'll cover:

• Overlay-Based SDN - and the questionable assumptions being made by others in this area (good for Gartner for calling these out!)
• The SDN Vendor Explosion Challenge,
• The "Unspoken Costs" of SDN Deployment, and
• The "How" of SDN is still missing.

I hope you find this useful and informative and as always, feel free to debate with me around my observations!

Overlay-Based SDN

Cisco's Padmasree Warrior has already been vocal on the challenges of taking a software-only approach to SDN.  It was good to hear healthy recognition of these challenges at the Gartner conference.  In particular, there is growing recognition that VMware's NSX approach makes 2 critical assumptions  (which I am sure you may find concerning):

(i) the (physical) network hasplentyof bandwidth: so be prepared to "over provision your network" is what I heard wrt NSX adoption, and

(ii) the (again underlying physical) network isalwaysworking -"Is it?!?!" I hear you say -so the reality of troubleshooting multiple network layers is indeed receiving attention.  If you're like me, you will know that networks are terrific but occasionally they do need serious troubleshooting from time to time ... and concerns were raised at the conference on how NSX's overlay approach would hinder this.

The SDN Vendor Explosion Challenge

At the conference, I heard the market landscape for SDN described in terms of 4 layers:

1. Device providers
2. Controller providers
3. Application providers, and
4. Service providers (e.g. firewall services etc)

In principle, if you decide on a multi-vendor strategy, you could envisage ending up with say 8 suppliers (2 for each of the 4 layers), giving a total of 8 vendors ... compared to say the 1, 2 or 3 vendors you may have in your network today.  Can you imagine the complexity?  Imagine having to align roadmaps across all vendors, test that they all inter-operate and so on.  Who will help  you troubleshoot the interactions between multiple components and multiple layers?  This unfolding market is not simply an N²problem, it could be an N⁸problem of complexity!

What I take from this, therefore, is that you should select very carefully who you partner with for your SDN needs.  It may well be that "less" is indeed "more" and that the solution providers such as Cisco are much more attractive and offer lower "total cost of ownership" across the whole solution.

The "Unspoken Costs" of SDN Deployment

Everyone is saying it.  I even heard it at the conference: SDN ...."Promises the ability to leverage low-cost hardware (e.g. white box switches)".  When you consider the planning, integration and troubleshooting costs that I outline in my previous point, it's easy to project that SDN may not be the "cheaper nirvana" that some are saying.  Sure, you may get additional flexibility and agility from SDN technologies, I for one am not hearing anyone say it will be cheaper.  In fact the "total cost of ownership" was not raised at the conference, reflecting the "loud silence" on this we hear across the industry.  So .... make sure your SDN deployment partner can help  you understand these "unspoken costs".

The "How" of SDN is Still Missing

Im my first blog on this topic, I outlined the market's fascination on the "What" of SDN -the features, protocols and specifications.  I made the case that the "Why" ("is it specifically good for me?"), and the "How" ("can we get it done") were missing.  And that's not changing fast enough, there isn't in my view sufficient focus across the industry on how you really can exploit the promise of SDN.  There are some exciting options where Cisco ONE can help address pressing networking challenges and help you generate innovative services and solutions -so how can you get started?

This is where Cisco Services comes in.  We have worked hand in hand with our Cisco R&D counterparts as the Cisco ONE and ACI technologies have been developed, and we have developed a rock solid methodology for evaluating and deploying the SDN technologies in Cisco ONE, all the way from helping you identify the key use cases for SDN that will add value to your business, right through to performance and scale testing to ensure your solution operates and performs as you specify it.  Please, then, get in touch and we'll be happy to help you find the right path to SDN success.