Some of us may recall the unmistakable sounds of a modem connecting to the Internet. Once the handshake was successfully negotiated, there was perhaps even a thrill experienced of having made it online. That was the world of the dial-up Internet connection. Exciting times back then. All of 40-50 kbit/second. Fast forward to the 25 Mbps and higher download speeds of today’s “always on” broadband Internet connections, and clearly we are in a different paradigm. Connecting to the Internet no longer seems as exciting, instead something mundane that could even be taken for granted.
Speaking of connectivity and networks, enterprise WANs have come a long way. From dial-up to T1/T3 to ATM to Frame Relay to MPLS, there has been a steady progression of new technologies. Though MPLS is said to be a service rather than represent a specific technology choice and could have ATM, Frame Relay, or even Ethernet at its core. Circuit switching to packet switching, so the transition happened. A trait of many of these WAN solutions appears to have been that they were very complex and called for specialized expertise. Also some of them even ran into the millions of dollars per month, so not cheap. The introduction of MPLS was possibly a game changer. But there don’t seem to have been very many technological advances in WAN technology over the last 15 years or so since MPLS came in. As an aside, this appears to reflect what some have observed to be an absence in fundamental tech advances per se in the last decade or two.
In the past, all was quiet and stable on the enterprise WAN. Users were either at the head office or at branch offices. Applications resided at the corporate office data center. Most of the traffic was branch to head office through the enterprise WAN. Internet traffic would traverse the WAN to the data center (backhauled) before being handed off to the ISP then on. MPLS met this use case very well. There was perhaps no need to make significant advancements to the WAN. Everyone was “happy” with the status quo.
Then things started to change. Lots of reasons. Marked by a rising use of software, the world began to go digital. More and more, the software started to be accessed from the cloud. Public and hybrid cloud became popular choices. There was an increasingly insatiable appetite for consuming video, boosting demands on bandwidth. VDI or Virtual Desktop infrastructure installs added to the clamor for higher connectivity. Then there were the remote users who don’t work from branch offices. Not to forget the Internet of Things with its billions of devices slowly but surely coming online and hankering for even more bandwidth. No wonder that the enterprise WAN began to come under pressure. MPLS was not geared up for such an intensely interconnected world.
Enter SD-WANs (Software Defined WANs). They promise to meet the demand by virtualizing connectivity options and offering an abstraction layer on top. So the underlying links could be either MPLS or the regular Internet. In order to optimize network reliability and availability, the software would “magically” send traffic through the appropriate link automatically, behind the scenes. There is even talk that SD-WAN could replace MPLS altogether and route traffic entirely through the Internet while meeting QoS and SLA guarantees. Though many users would probably balk at doing away with MPLS. After all who wants to take on too much risk? Therefore, the future seems to lie in a hybrid WAN architecture, part MPLS part Internet.
SD WANs therefore certainly look good from the enterprise standpoint, essentially more bandwidth and performance for significantly less outlays. A no brainer, one would say. But how about examining this scenario from the ISP end? Service providers are seeing traffic on their backbone networks go up tremendously. However much of this traffic increase is low revenue or no revenue. The investments needed to make improvements to the backbone network (some of which are based on circuit switching based equipment circa 1990s) are not matched by a corresponding rise in revenues from the investment.
Consequently, there appear to be two possibilities. Either the infrastructure investments are not made in which case performance could start to slide. Or ISPs could start to raise prices for regular broadband Internet access (assuming there are no regulatory constraints). Anyways you look at it, the model seems to start to break down.
Perhaps SD-WAN is a temporary solution, a placeholder if you will. More fundamental innovations are probably required in WAN technology to meet the surging demand for bandwidth and service levels. Clearly a new equilibrium has to be found at the intersection of demand for bandwidth from enterprises (and consumers) and the supply of bandwidth from service providers. Assumptions of unlimited broadband and unlimited cloud may not be tenable. An all-digital world may have to wait for the network to catch up, the WAN divide may yet slow the digital march.