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Susan Fogarty
Susan Fogarty
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7 Essentials Of Software-Defined Networking

What is SDN? If you have to ask, you're not alone. We boil SDN architectures down to the essentials, including OpenFlow, SDN APIs, and overlay networks.
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Software-defined networking (SDN) may be the technology du jour, but as of yet it is largely conceptual -- and those concepts vary depending on the approach. Vendors talk about their own SDN architectures, OpenFlow, SDN APIs, and overlay networks either as if they are interchangeable, or without ever mentioning the other options. It's no wonder that SDN leaves many folks in IT with no grasp of the "definition" at all.

The basis of SDN is virtualization, which in its most simplistic form allows software to run separately from the underlying hardware. Virtualization has made cloud computing possible and now allows datacenters to dynamically provision IT resources exactly where they are needed, on the fly. To keep up with the speed and complexity of all this split-second processing, the network must also adapt, becoming more flexible and automatically responsive. We can apply the idea of virtualization to the network as well, separating the function of traffic control from the network hardware, resulting in SDN.

Whether out of a need for self-preservation or a desire to improve technology, the networking industry is embracing SDN with surprising enthusiasm. Legacy networks have serious limitations and old methods that simply will no longer work. As virtualization, cloud, and mobility create more complex environments, networks must be able to adapt in terms of security, scalability, and manageability. Most enterprise networks, however, rely on fixed boxes and appliances requiring a great deal of manual administration. Changing or expanding these networks for new capabilities, applications, or users requires reconfiguration that is time consuming and expensive.

Software-defined networks take a lesson from server virtualization and introduce an abstraction layer separating network intelligence and configuration from physical connections and hardware. In this way, SDN offers programmatic control over both physical and virtual network devices that can dynamically respond to changing network conditions using OpenFlow or some other programmable and controllable packet/flow processing protocol.

There are several approaches to SDN, but the most common components and concepts are covered in the following slides. Though the technology is very much in the midst of its development, vendors and industry organizations are working to make the technology open and flexible while adhering to existing Internet standards. At its core, SDN promises to enable network technology innovation and versatility while reducing complexity and administrative overhead.

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Marilyn Cohodas
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Marilyn Cohodas,
User Rank: Apprentice
11/19/2013 | 9:35:50 AM
Great Slide Show on a Complex Topic
Sue, Thanks for boiling down this abstract -- and very hot -- topic into key fundamentals  I know I'm going to bookmark the page and refer back to it as trends develop and technologies mature. 
Li Tan
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Li Tan,
User Rank: Apprentice
11/20/2013 | 9:17:51 AM
Re: Great Slide Show on a Complex Topic
Marilyn, I am so glad to see you again.:-) I am with you on this post. This is a great introduction to SDN and presented the essential idea. In old days we talk about MPLS VPN, Juniper Virtual Switch and Virtual Router. They have the concept about virtualization but it's not really SDN. Now the technology evolves so that we have this kind of cutting-edge architecture. I do believe that SDN is the future for networking - today still the physical network infrastructure is not used in its most efficient manner.
Marilyn Cohodas
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Marilyn Cohodas,
User Rank: Apprentice
11/20/2013 | 9:30:31 AM
Re: Great Slide Show on a Complex Topic
Great to see you participating in the InformationWeek community, as well, Li. I know you've been following SDN with keen interest over the past few years. Do you still have a feeling of "Still Don' kNow". Or is it starting to make more sense?

If it's the latter, I wonder if you could share your understanding of the technology and some of the use cases that you might be familiar with or can imagine.

 
Li Tan
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Li Tan,
User Rank: Apprentice
11/22/2013 | 1:22:51 AM
Re: Great Slide Show on a Complex Topic
Marilyn, thanks for the greetings - yes now I feel much more comfortable with SDN. From what I understood, the essence of SDN is the separation of control plane and data plane. This is not some new concept and modern switches/routers adopted it widely. But SDN put the physical network infrastructure as a pure resource pool and data plane. Instead by making the control plane ("controller" in SDN terminology) separate and providing necessary intelligence/programming API, SDN offers not only higher efficiency on resource utilization, but also provides possibility for redefining the virtual overlay network. So far I did not see so many great examples in the market but I do believe it will contribute more and more to IT area, especially cloud computing and big data.
virsingh211
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virsingh211,
User Rank: Apprentice
11/22/2013 | 3:09:28 AM
Re: Great Slide Show on a Complex Topic
From our past we learned split architecture from PSTN to VoIP with MGW connecting to CS services (MSC Server) and IMS Services (MCRF) using BICC, H.248 on IP, but now it will be SDN convergence with Data plane and Network operating system on control plane.
Susan Fogarty
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Susan Fogarty,
User Rank: Strategist
11/20/2013 | 11:23:49 AM
Re: Great Slide Show on a Complex Topic
Li, thanks for your comment. I am glad you found this an adequate overview. I thought readers might appreciate a basic explanation of the technology without all the complexity of how each vendor is approaching SDN. Are you experimenting with SDN yet?
FredB256
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FredB256,
User Rank: Apprentice
4/22/2014 | 8:29:32 PM
Re: Great Slide Show on a Complex Topic
I would have read this, but an ad on every slide exceeded the utility of the information. I am sure it was a good article, maybe put it in a less obxnous place next time.
Michael Endler
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Michael Endler,
User Rank: Apprentice
11/19/2013 | 9:44:12 AM
Good intro to SDN
A good explanation. SDN is one of those much-buzzed topics - like the Internet of Things - that people frequently mention without really understanding. As Cisco, Dell and others advanced somewhat different definitions of SDN and what it's supposed to do, it will be important for IT decision-makers to wander into the weeds to select the model that's best for their needs.
HaileyMcK
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HaileyMcK,
User Rank: Apprentice
11/19/2013 | 9:57:28 AM
Word of the day
SDN is certainly the word of the day. I suspect that eventually our networks will be, by definition, software defined. In the meantime, this is really helpful primer. Thanks!
virsingh211
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virsingh211,
User Rank: Apprentice
11/19/2013 | 10:31:56 AM
Re: Word of the day
I agree on SDN being word of day, but as it is approaching closer day by day, i feel its getting complicated for IT managers, is there any rules you would suggest as we travel on SDN road..
Susan Fogarty
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Susan Fogarty,
User Rank: Strategist
11/19/2013 | 3:38:05 PM
Re: Word of the day
Virsingh211, I couldn't agree more that SDN is extremely complex, not only in technical concept, but also in the way the vendors are approaching it and attempting to integrate open standards. (Check out today's commentary, SDN Upends The Switch & Router Market.) My advice would honestly be to wait and see. Also to fully understand the business challenges you are trying to solve and what you'd like to achieve before making any technology investments. 
sam masud
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sam masud,
User Rank: Apprentice
11/20/2013 | 12:17:53 PM
Re: Word of the day
Susan,

When it comes to SDN, I feel for IT managers. While Google perhaps is the most well know example of a company that implemented SDN in the data center and in the network interconnecting their data centers,  what I understand is that Google deployed a modified version of the OpenFlow protocol (GoogleFlow?). And they did deploy SDN pretty quickly. But how many IT managers have the resources that Google has?
Susan Fogarty
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Susan Fogarty,
User Rank: Strategist
11/20/2013 | 5:59:45 PM
Re: Word of the day
Sam, I share your sympathy. I read about how companies are embracing SDN because current products didn't allow them to do what they needed with their networks, and I understand that. But for every company (like Google) that has a team of network engineers working out the complexities of virtual resource allocation, there are probably a thousand with limited networking and data center expertise who are very worried about how this will affect them. 
virsingh211
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virsingh211,
User Rank: Apprentice
11/21/2013 | 6:24:42 AM
Re: Word of the day
@Susan, i guess my comment went in different direction, you might interviewed or met number executives around you, how many of them do you think are aware and had knowledge on SDN...i am not sure about there in US but people i meet still only SDN= Software Defined Networking...
Susan Fogarty
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Susan Fogarty,
User Rank: Strategist
11/21/2013 | 10:06:43 AM
Re: Word of the day
Virsingh, I think awareness is probably just beginning, as you say. Companies that define themselves and really rely on their network as a basis for their business are much more ahead of the learning curve, I would say.
MarciaNWC
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MarciaNWC,
User Rank: Strategist
11/19/2013 | 11:39:53 AM
SDN clarity
I really like how this slideshow cuts through all the different SDN messages and approaches to focus on essential SDN concepts. It brings a lot of much-needed clarity to a very important topic.
sam masud
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sam masud,
User Rank: Apprentice
11/19/2013 | 4:09:58 PM
SDN numbers
Susan,

I've come across various market estimates for SDN, and to be frank, I wonder if we can really predict the SDN market at this time since there is really is nothing to go by (no baseline) other than the traditional switch-router market. And the latter might not be a very good predictor for SDN since SDN probably will have much lower prices compared to switches-routers.
Susan Fogarty
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Susan Fogarty,
User Rank: Strategist
11/20/2013 | 11:18:01 AM
Re: SDN numbers
Sam, you have a good point about the market numbers. The chart I oncluded here was from the most recent analyst report I could find. It also includes revenue from associated equipment and support services -- so that defiition could be very widely interpreted.

I included it less for th exact data and more as a wake-up call to anyone who thinks SDN might be a passing fad. When you look at that kind of projected growth, it's hard to ignore it and hope it will just go away ;)
sam masud
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sam masud,
User Rank: Apprentice
11/20/2013 | 12:03:27 PM
Re: SDN numbers
Hi Susan,

I really was not being critical about the numbers, but trying to make the point that various market estimates related to SDN should probably only be viewed as providing a sense of how this market might grow going forward since we have no historical data upon which to forecast the market with any accuracy.

Something else that comes to mind is that much of the SDN activity currently is targeted at the at the data center. Service providers, as far as I know, are taking a much more cautious approach, although I'm pretty sure they too will embrace SDN. Yet another market for SDN is the campus network--again I'm not hearing much at this time about SDN in the campus.
eamonwalsh80
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eamonwalsh80,
User Rank: Apprentice
11/24/2013 | 2:27:04 PM
SDN Is Changing Everything
The demand for SDN is being driven by major communications service providers and major enterprises, versus the network equipment manufacturers (NEMs).  If you were a telecom service provider or other major consumer of network infrastructure equipment, SDN is in theory very attractive for various reasons, such as the ability to only wire your network once and only once and use centrally controlled, lower-cost switches from multiple vendors

 

SDN is still in "early adopter" stage but moving fast.  Companies like Google and Amazon have proven out the concept.  However, market requirements to support service providers and major enterprises are still evolving.  What are the various use cases that need to be supported?  What type of programmatic interfaces should be presented?  What types of network applications need to be supported?

http://h17007.www1.hp.com/docs/reports/Lippis_Report_210_BN.pdf
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