The OpenFlow Longbow


carck_longbow

The label of disruption seems to be thrown around quite a bit.  I’ve heard tablets being called the disruptive technology when it comes to PCs.  I’ve also heard people talking about software defined networking (SDN) as the disruptive technology to the way that we’ve been doing networking for the last decade.  Nowhere is that more true than with OpenFlow.  But what does this disruption mean?  Aren’t we still essentially forwarding packets the same way we have in the past?  To get a frame of reference, let’s look at one of my favorite disruptive technologies – the longbow.

Who Are Yew?

The Welsh yew longbow had been a staple of the English military as far back as 600AD.  The recurve shape of the bow provided for a faster, longer arrow flight than the shorter bows used by foot soldiers and mounted calvary.  The wood was especially important, as the yew tree was only really found in abundance in Wales.  Longbows existed in one form or another in many armies in Europe, but the Welsh bow was the only one that was feared.

The advantage was never more apparent than during the Hundred Years War between England and France.  The longbow was deployed as a mid-range artillery to harass advancing troops.  There are questions about whether or not the arrows were able to pierce the plate armor used by knights at the time, but the results of archery corps can’t be denied.  Especially in the Battle of Agincourt.  The English used longbows to slow the advance of French forces in armor, tiring them out as they crossed the field and holding them at bay until the heavier foot soldiers of the English army could be repositioned to take the advancing enemy apart.  Agincourt was a win for the English and fives years later, the war was over.

The longbow proved itself to be a very disruptive technology.  Not because it killed soldiers better or faster than a mace or broadsword.  It was disruptive because it changed the way generals composed their armies.  Instead of relying on heavy assault troops in armor to punch a hole in the enemy lines, the longbow forced a soldier to become more mobile with less armor to be able to cross the range of the bow much more quickly and close to a range where the technology advantage was negated.  Bowmen were at a distinct advantage at point-blank range.  Armies grew more mobile all the way up to the point where a new technology disrupted the reign of the longbow: gunpowder.  Once musketeers became more prevalent, they replaced the role traditionally held by the longbow archer.

Disrupting the Flow

How does this history lesson apply to OpenFlow?  OpenFlow is poised to disrupt networking in the same way as the longbow forced people to take a new look at their armies.  OpenFlow takes something we know about and turns it on its head.  It gives us much more control over how a switch forwards packets.  It also makes us ask questions about how we build our networks.

Questions about big core switches, spine-and-leaf topologies, and the intelligence of edge devices all become very pertinent in an OpenFlow design.  Should I put a larger switch at the edge since it’s going to be doing a lot of heavy lifting?  Should I use a fabric in place of a three-tier design?  Will my controller allow me to use different interconnects to ensure high-speed traffic flows east and west in the data center?

OpenFlow is taking over some vendors offerings.  NEC and HP have already committed to OpenFlow designs.  Even companies that haven’t really embraced OpenFlow have decided to offer it rather than dismiss it.  Arista and Cisco are offering new switches that have support for OpenFlow, even if that support may not extend to more proprietary enhancements right now.  Just like the longbow, OpenFlow is forcing the opposition to reconfigure the way they fight the battle.  They may not like it.  They may even say in private that they’re just doing it to mollify a part of the customer base looking for specific points in an proposal.  But they are still dedicating time and effort to OpenFlow all the same.


Tom’s Take

Disruption happens all the time.  We don’t use cell phones in bags hardwired into our vehicles any more.  Our computers are the size of a broom closet and run off of punch cards.  Just like weapons in the ancient world, whoever comes up with a more effective way of winning battles enjoys a distinct advantage for a time.  Eventually, something comes along that disrupts the disruption.  OpenFlow is currently the king of the SDN battlefield.  It holds that title by virtue of how many people are racing to interoperate with it.  Eventually, it will be dethroned just as the longbow was.  They key will be recognizing the next new thing first and using it to your advantage.  And arming your archers with it.

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