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In an abstract way, Software Defined Networking controls the forwarding plane elements remotely for the purpose of determining communication path and other controlling matters. I learned that SDN forwarding plane consists of (programmable) switches which is sometimes denoted by OpenFlow-based switches such as OpenvSwitch. However, I've read multiple times that SDN can be used to remotely control real conventional hardware switches!! This really changes everything I've learned so far! Is that really possible?

  • Can you share where you see that SDN can be used to remotely control real conventional hardware switches? I'd like to look at it. – Ron Royston Jul 23 '16 at 1:58
  • It is here sdxcentral.com/articles/contributed/… – Michael Jul 23 '16 at 2:47
  • What do you think about this post? – Michael Jul 23 '16 at 3:28
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    I think that article discusses how switch manufacturers can modify existing types and models of switches at the physical layer, then add some software to enable an openflow type feature support. Sort of retro-fit it on. – Ron Royston Jul 23 '16 at 3:53
  • I agree Ron ... – Michael Jul 23 '16 at 4:28
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Good question.

First, as I indicated in What Exactly is SDN?, if it ain't running the trademarked OpenFlow® protocol, it ain't SDN, it's SDN Fashioned. OpenFlow®'s owner, the ONF, spells out a Software-Defined Networking (SDN) Definition which specifies that the OpenFlow® protocol is a foundational element for building SDN solutions.

Cisco, for example, owns and markets an SDN fashioned solution called Cisco Application Centric Infrastructure (ACI) which they say is better and more feature rich than plain old SDN w/ OpenFlow®. Cisco also markets a pre-packaged plug&play SDN fashioned product called Cisco Meraki.

VMWare offers an SDN fashioned product called NSX. With their solution, the SDN functionality is an overlay. They basically tunnel/encapsulate another network on top of the existing underlying IP network and Ethernet switches.

Finally, to answer your question, in order for an Ethernet switch to be controlled by an SDN controller it must speak OpenFlow® or some vendor specific flavor of something similar such as Cisco's OpFlex.

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    As I also mentioned in your other answer, just because a vendor says their product is a "foundational element" for building X doesn't mean their product is the only product that is X. I have seen plenty of sales/marketing call their product "foundational" to X over the years (and I also provided such an example in comments to your other answer). SDN as a term and concept predates Openflow, not vice versa. Openflow is simply one solution that follows the concept developed by others. – YLearn Jul 23 '16 at 4:14
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    Again with the Meraki bull. Merkai is CLOUD CONFIGURED It is NOT remotely SDN. Get a Meraki switch. Or talk to a Meraki sales engineer. It's not f'ing "SDN". You, the user/admin, going to some external web site to configure it does not make it SDN. – Ricky Beam Jul 23 '16 at 21:37
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    @RickyBeam I have been to 500 Terry A. Francois Blvd (Their HQ) - they flew me there; I've spoken with them. Looking at the architecture, it's SDN fashioned at the core - physical separation of the network control plane from the forwarding plane. Why does that make you so upset? – Ron Royston Jul 23 '16 at 23:15
  • @YLearn "SDN as a term and concept predates Openflow" is exactly wrong. The Term SDN was first mentioned in an MIT Academic Article on OpenFlow Greene, K. 2009. TR10: software-defined networking. – Ron Royston Jul 23 '16 at 23:26

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