Software defined networking: Hype or hope?

Moderated by Lawrence Dignan | March 11, 2013 -- 07:00 GMT (00:00 PDT)

Summary: Sure, SDN is a great idea. But will it get industry support?

Robin Harris

Robin Harris




Steven J. Vaughan-Nichols

Steven J. Vaughan-Nichols

Best Argument: Hype


Audience Favored: Hope (56%)

Closing Statements

SDN is a good idea. But...

Robin Harris

Don't believe the hype. SDN is a good idea. But it depends on big vendors supporting it in a multivendor environment.

I wouldn't hold my breath.

Cisco, in particular, is experienced in meeting standards and then adding extra goodies that lock-in users. In addition, and I've seen this before, vendors will achieve a level of interoperability that demos well but isn't quite ready for the data center.

So yes, Stephen may be correct that you will have something called SDN in your networks in a few years. But the question we're debating is whether SDN will live up to the hype.

Anyone who has watched big multivendor initiatives before knows that vendors will do everything possible to retain their high margins. And if SDN doesn't reduce those margins, it will be just another checkbox item.

Readers are voting with their hearts. In five years their heads will know the truth.



SDN is coming and it can't be stopped

Steven J. Vaughan-Nichols

You know, I really don't even think this is a debate. SDN will be in your network in the next few years. Period. End of statement.

All the major network vendors are behind it. Heck, even companies like Microsoft and VMware, which are not companies you think of when you talk "network", are investing in it.

The real question is: Will SDN remain open enough that the term still has meaning, or will it just divide up into incompatible network management fragments?

We've already been down that failed road before so I think that this time the network players will make sure that at least basic interoperability will be present in everyone's take on SDN.

This, in turn, will make networking infrastructure and management cheaper and thus make it more attractive to the real rulers of IT these days: the CFOs. SDN will prove to be omnipresent in networking in the coming years as gigabit Ethernet is today.


In the short term and long run

Lawrence Dignan

Picking a winner in this debate really boils down to time frame. In the short term, Robin Harris has the best argument. SDN is largely hype at the moment as the building blocks are being put into place. In the long run, Steven J. Vaughan-Nichols has a better case.

Overall, I have to pick a winner based on the current rebuttal and Robin had a more eloquent case. 


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  • Unless you're talking about the data like layer, it's incoherent.

    Unless you're talking about the data link layer, it sounds incoherent to me.

    You do need to transport information via wires or some other physical method. I can't program an isolated computer to talk to another isolated computer merely by writing code. At some point or another, I have to connect the computers somehow to each other.

    So you'll always need a physical layer. That can't be moved to software.

    Above the physical layer is the data link layer - which is pretty much hard wired into the networking device, be it an Ethernet card, router, Bluetooth device, etc. This is the only layer that is normally hardware that could maybe be moved to software.

    But to be honest - I don't see a big need to move the data link layer to software. It's not broken. It's not performing poorly. It does one thing, and it does it well - it provides the lowest level packets that higher levels can use. Anything more complex should really be handled at a higher level.

    Above the data link layer - well above that, it's all software anyways. Be it in router firmware or as a part of the OS's TCP/IP stack, it's all software, and it would be quite absurd to NOT call it "software defined networking," because anything above that is in fact defined by software.

    So - it's impossible to move the physical layer to software, and anything at or above the network layer is already software, so . . .

    . . . so I'm interested in why you think the data link layer needs to be moved to software. Don't disappoint ;).
    Reply 2 Votes I'm Undecided
    • Data LINK layer

      Where's my edit button???????????
      Reply 1 Vote I'm Undecided
  • Better name for it . . .

    BTW, a better name for it would likely be "centralized administration," not "software defined networking." The entire concept seems to be about moving away from a control panel for each device towards a single, central place where they can be administered. Why must buzzwords dictate language?

    I think the concept is real and solid - but the buzzword is horrible, and a terrible description of what's really going on. Can I plead for ZDNet to quit using buzzwords? Please?
    Reply 2 Votes I'm Undecided
  • Pretty much all networking is software defined

    It's only the bottom-layer protocols that are built into the hardware.
    John L. Ries
    Reply 1 Vote I'm for Hype
  • Television solidified it's 525 line standard in 1941.

    That probably seemed to go against the television manufacturers then, too.
    Reply Vote I'm for Hope
  • I don't get the point of SDN anyways.

    It still has to run on something. Routers and switches are purpose built devices that are suited to do what they were designed for. Why would I even bother to virtualize that functionality?
    Reply Vote I'm for Hype
  • Overhyped

    Only if the control plane standardization is implemented by all the vendors will this get any traction.
    When and if you can use separate management products for router/switches then SDN will come of age.
    Reply Vote I'm for Hype
  • Manageability more than performance

    It's a big topic; I'm unsure how to address it a live-update-at-a-time.

    Robin is ENTIRELY right to recall the storage mess of the last *decades*. SDN is shaping up much like that. VMware and Cisco are *clearly* angling to make SDN into "lockin-by-another-name".

    Still, I see great promise in SDN. To all those emphasizing that there must be physical reality underneath it all: true, but SDN is NOT just about performance. Equally important, in some contexts, is manageability. For some situations, SDN is the difference between a five-minute deployment, and a five-day one.

    Yet another perspective: SDN is a necessary part of SDDC, and Cthulhu knows how much we need *that*.
    Reply Vote I'm Undecided
  • I get centralized control, but don't get why it needs to be "virtualized."

    I get centralized control, but don't get why it needs to be "virtualized." Why would you want to layer on a "virtual network" that basically lies to you about the actual topology of your physical network?

    That actually sounds like a formula for failure: Since the virtual network may not reflect the topology of your physical network, optimizing the virtual network may actually kill performance, as it's not matching the topology of the real, physical network.

    Okay, so you've made your dream network by virtualizing everything. Except it's ignoring the topology of your actual, physical network, and thus is actually hugely inefficient.

    I can imagine trying to create a virtual ring network on top of a standard hierarchical physical network. A virtual ring network sounds good in theory, but on top of a hierarchical physical network will be an enormous waste, as it has to has to constantly go up and down the hierarchy to visit each node on the way to the destination.

    Not such a hot idea IMO. If you want to optimize your network, it should be done at the actual physical level, not at some abstracted virtual level.

    Having a centralized, easy to access control panel to control routing for the entire network? Great idea. Layering some other "virtual network" on top of your physical network, so that you can play around with typologies that may not reflect the realities of your physical network? Not such a great idea, IMO.
    Reply Vote I'm for Hype
  • SDN is just another good hyped Open Source idea

    Open Source will always be with us, keeping costs down. Hardware vendors love it for that reason, so it's not surprising that SDN has a good bandwagon. However, I don't see how you can allow a mission critical infrastructure item to be Open Source; like Android, you would have too many flavors and too little support when things have to work.
    Reply Vote I'm for Hype