We Need Consistency more than Controllers

I was listening to the I2RS Packet Pushers podcast a while ago and was more than glad that when Greg Ferro yet again mentioned the complexity of OSPF, someone simply pointed out that controllers would not reduce the complexity; if anything they would increase it.

While the controllers might give you the appearance that things are simple (particularly when you’re looking at a glitzy GUI that looks amazingly good on PowerPoint slides), you’re effectively trading the explicit complexity for implicit complexity that you’re not aware of that will eventually haunt you (more so when you start dealing with leaky abstractions – see also The Law of Leaky Abstractions).

How about doing a proper network design, standardizing configurations that are deployed in consistent manner across all devices, and then you know (if you need to know) what’s going on – the moment you deploy an SDN controller (particularly one with centralized control plane), you won’t know at all what’s going on behind the scenes… and I have yet to see a commercial OpenFlow controller documentation that describes in sufficient details what happens between the controlled network devices and what flows are installed in each device.

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  1. I didn't listen it yet but probably Russ mentioned that controllers do not reduce the complexity and I somewhat agree. Thanks Ivan for reminding that podcast , I should listen it :)
  2. What would end up happening is what happens with Windows servers. Oh it doesn't work, let's reformat and start over.
    1. Don't forget Wally ...http://dilbert.com/strips/comic/2012-07-21/

      ... and I don't think there are many organizations that can afford to reformat the network.
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