SD-WAN: Pushing Abstraction Past the Edge

Software defined networking (SDN) is usually characterized by its ability to simplify and amplify datacenter infrastructure. But the boundaries between the datacenter and the world around it are becoming increasingly thin, which is leading many developers to start thinking about SDN on the wide area network (WAN) as well.

So-called SD-WAN is emerging as an equal partner to SD-LAN under the broader SDN framework, based on the need to implement connectivity across long distances without tapping into carrier-class NFV solutions. According to Citrix’s Karl Brown, SD-WAN targets key capabilities like real-time provisioning and configuration that organizations require between main offices, branches, partners and other remote sites. These are supported by SDN-facing virtualization and optimization layers, coupled with secure Internet access and interoperability with third-party infrastructure. To that end, the company is developing its CloudBridge platform as an end-to-end solution by integrating tools like the ZScaler Security as a Service offering and fostering interoperability with orchestration vendors like Glue Networks.

It would be nice if the enterprise could simply extend its local SDN platform across the wide area, says Viptela’s Ramesh Prabagaran, but while single-vendor platforms can cover both topologies, the wide area must have its own configuration in order to meet service requirements. For one thing, SD-WAN must account for the highly unpredictable nature of the wide area, which often encompasses a range of hub-and-spoke and mesh networks, not to mention regional aggregation designs, traffic-engineered pathways and other features. As well, the WAN usually houses numerous network security protocols, varying loss, latency and jitter characteristics and any number of QoS requirements. All of this must be accommodated in the SDN policy engine once data leaves the more stable, layered LAN.

A software defined WAN is likely to become a common facet of the enterprise network going forward considering the havoc that increased data flows and rapidly scaling interconnectivity will cause to MPLS architectures, says VeloCloud VP of Marketing Mike Wood. As he explained to Fierce Enterprise Communications, bandwidth requirements could quadruple or more by the end of the decade due to increased use of voice, video and other data-heavy applications. Without SD-WAN, the enterprise would be forced to eat the cost or push networking onto the public Internet, which doesn’t provide the most reliable service. SD-WAN allows organizations to optimize bandwidth dynamically, creating network pathways that are both resource-efficient and reliable.

But since this is the wide area we are talking about, data will likely touch a range of vendor platforms, which makes interoperability a key requirement. At last month’s Open Networking User Group (ONUG) in New York, Silver Peak showed off a multi-vendor demo using the Unity EdgeConnect system as the lynchpin for six leading data platforms, including Nutanix’ converged infrastructure solution, Infoblox DDI address management and the Amazon Web Services cloud. The goal was to demonstrate the ability of disparate vendors to meet highly targeted system interoperability requirements in order to create a common virtual networking framework.

No man is an island, and the same goes for the datacenter. In an increasingly interconnected world, the load on wide area infrastructure will not only increase, but become more complex. Abstraction on the WAN must evolve in conjunction with abstraction within on the LAN or you wind up with a set of highly dynamic network services that cannot extend beyond the datacenter.

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