Huh?
Since SDN controllers have to deal with traffic as flows (meaning they have to remember MAC addresses so as to track conversations, compared to an Ethernet switch that only has to know which port it's forwarding traffic to), network scalability is also a big problem.
First, ethernet switches (bridges) inherently remember MAC addresses, or they wouldn't know which ports to which they should forward traffic.
Second, can we really assume that these SDN controllers are using MAC addresses to track conversations? I would expect it to be far more likely to use source/destination IP addresses and ports, same as every other L4 traffic controller (firewall, load balancer, proxy, etc). No idea how the SDN controller could function for Internet scenarios, since it won't have MAC info from at least one of the ends.
Biting the hand that feeds IT
