By Dante Malagrino, Co-Founder, President & CEO, Embrane

Established in 2009, Silicon Valley based Embrane designs and develops software solution for delivery and management of network services in data centers. The company has recived a total of $18 million funding from Lightspeed venture partners, New enterprise associates and North Bridge Venture partners.

In a recent post on his blog (Twilight in theValley of the Nerds), Brad Casemore brought up some interesting questions about the possibility of extending a Software Defined Network (SDN) as defined in the Nicira announcement to deliver L4-7 Network Services.

While I am not aware of Nicira's future plans, there are a couple of considerations that I would like to offer, in an effort to clarify why we so stubbornly point-out the difference between layer 2/3 and layer 4/7; why the two things are quite different; and why they each will require different approaches even as we move to a software-defined world.

There are several ways to look at the difference between layer 2/3 and layer 4/7, but the fundamental point is that an architecture designed to support packet forwarding (layer 2/3) cannot be simply adapted or extended to support flow processing (layer 4/7) and vice versa. Making that assumption would almost be like claiming that a switch or router could be interchangeably used as a server or the other way around.

An interesting way to validate the statement above is that companies like Cisco with obvious dominance in the layer 2/3 market have not had any unfair advantage against newcomers such as F5, Riverbed and others. Likewise, these companies have not been able (and they have not even attempted) to get into the routing or switching markets despite having been very successful in their respective layer 4/7 segments.