Virtualization in the WAN: Where It's Headed

The contrast between virtualization in the data center, discussed in my previous No Jitter post, and virtualization in the WAN is interesting.

We've had WAN virtualization, in the form of VLANs and VPNs, for decades, but virtualization in the data center has emerged only in the last several years. Now data center virtualization is accelerating, and predicting what will happen (if anything) in the WAN space is much harder. Perhaps the virtual WAN will depend on the virtual data center... or not.

SDN as starting point
Software-defined networking (SDN) is a growing factor in data center switching, and as SDN's role in the data center expands, the technology will begin to percolate out into the WAN. We can first expect this to happen with data center interconnect (DCI) applications, and eventually that could make SDN the dominant strategy for intra-cloud connectivity. This is particularly true for service providers, as well as for enterprises that use private fiber, wavelength services, or TDM connections for their core networks. The result would be one giant virtual switch linking all the servers in all the data centers.

The limiting factor here is that SDN doesn't do as much if you have to run it across an existing IP infrastructure, like an enterprise VPN. There's still a lot of WAN that isn't impacted by virtualization beyond the current VLANs and VPNs, even for larger enterprises that have DCI applications. To get to the rest of the WAN, we have to look at another dimension of SDN expansion from within, and to another virtualization model emerging -- SD-WAN.

SDN, in its pure OpenFlow form, is great for creating tunnels or virtual wires. If network operators deploying SDN for their data center and DCI networks also offer public cloud services or want to share transport services between their own data center/cloud networks and enterprise services, they could end up extending the scope of their SDN virtual wires. Carrier cloud deployment to the edge, or "edge computing," is the eventual result. Given availability of SDN virtual wires in central office/switching centers, network operators could sell these SDN virtual wires to customers or use them to build other services.

Read the rest of this article on No Jitter.