Extending SDN to the WAN

Comments: 0 Runtime: 2:48 Posted: April 2nd, 2015

The focus of SDN is transitioning from the data center to new use cases, like the WAN. Organizations are looking to apply SDN functionality to scenarios such as dynamically load balancing  over multiple transmission links. The concept of a software-defined WAN is embryotic, but exciting because the WAN has been staid for so long.


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In the old days of SDN, maybe say a year ago or eighteen months ago, in the case of SDN that's the old days, we focused entirely on the data center. Now there is much more discussion of used cases in both the branch office and, something that excites me, the wide area network.

Let's put the wide area network in perspective. Service providers rolled out MPLS 2002/2003 time frame, and there has not been a fundamental success of a MPLS rolled out since nor are any in the pipeline. So enterprises are a situation where they basically have two wide area services, the internet and MPLS, it's been very very staid.

Now what a lot of enterprises have done, they said "I don't want to back-haul all my traffic over MPLS to my data center to hand off to the internet. I'm paying expensive MPLS prices for that, and I'm adding delay. What I'll do it in my branch office is I'll have a T1 access to a MPLS service and I'll have some kind of broadband internet access. Some traffic goes here and some traffic goes there." That kind of static allocation of capacity is an anathema to us these days.

One of the definitions of software to find WAN, and we're very early on in just what the definitions are, is to take SDN type intelligence and functionality to be able to dynamically load balance over multiple links. Now this could be T1 to MPLS and broadband to the internet. It could be two broadband Ethernet connections; let me give you an example of that. Maybe I have DSL access and I have 4G access. By definition they have diverse routing. My availability with DSL and 4G, or the internet, is at least as high as it's going to be with a single MPLS link.

Again, the definition of software to find WAN is still in flux, but a piece of it again is to use SDN type functionality to dynamically load balance traffic over multiple transmission links and of course people are going to layer other functionality on top of that, such as how to optimally route through the internet to go from a branch office to, say, Office 365. Embryonic and new, but very exciting because the WAN has been so staid for so long.

Written by Jim Metzler
Founder Ashton, Metzler & Associates

Jim Metzler is an expert at researching and analyzing emerging technology trends within the networking and service provider space.