[Paper] B4: Experience with a Globally-Deployed Software Defined

Jimmy Hess mysidia at gmail.com
Sat Aug 17 23:02:44 UTC 2013

On Sat, Aug 17, 2013 at 2:32 PM, Avi Freedman <freedman at freedman.net> wrote:

> No, people never use *flow controllers* for anything.
> People have been doing SDN since before Google was around.
> OK, so it was horrible expect scripts but it worked.
Not really.

Automatic reconfiguration of routers is not what a software-defined network
It is  one of the things (but not all of the things)  that SDN provides.

A software defined network is one where the forwarding behavior can be
completely defined
in software running outside of the devices that perform the forwarding.

You can write expect scripts all day; but you cannot turn your basic switch
into a Load balancer  or stateful firewall with one.
or decide in real time exactly which destination Ethernet ports a packet
 coming in a certain port is going to touch,  without having structured
VLANs and  static MAC tables on the switches ahead of time.

Changing device configurations with expect scripts is a limited tiny subset
of what SDN is.

> Avi

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