Software-Defined WAN (SD-WAN) startup Viptela has landed Singapore Telecommunications Limited (Singtel) as a customer, where Viptela's technology will be used to deliver the Singtel ConnectPlus SD-WAN service.

The two companies say that "multiple enterprises" are in pilot deployments of services using Viptela technology, called the Secure Extensible Network (SEN), which enables customers to manage VPNs and applications policies through a combination of software and controllers. Singtel's ConnectPlus service will be available in Asia-Pacific, Australia, Europe, and the United States.

Viptela raised $33.5 million from Sequoia Capital. More than $360 million has been invested in cloud WAN startups.

Cloud WAN technology will virtualize current enterprise WAN technology functions such as branch-office routers, Virtual Private Networks (VPNs), WAN Optimization, and Application Delivery Controllers (ADCs). All of these functions, which in the past required specialized routers and network appliances, will be moved to the cloud and managed with software.

Viptela does just that, adapting existing corporate VPNs to the cloud using an encrypted overlay technology that separates data and control functions and removes them from physical routing hardware. It can also enforce application policies, allowing the network to prioritize certain applications for higher performance.

One of the keys to Viptela's approach is that it integrates existing MPLS technology, rather than replacing it. MPLS has been a focus of many SD-WAN players because of its predominance in corporate networks. It's also expensive. Some SD-WAN players propose replacing MPLS by using encryption and WAN optimization over the Internet. But Viptela officials say that MPLS connections can be moved to the cloud and managed along with other applications and protocols using an overlay technology, rather than replaced entirely.

The best way to think of Viptela is as a service-aware, virtualized routing technology with centralized software control. What's more interesting is how Viptela is going to market, giving service providers a way to more quickly launch managed services. The company says it will also market to enterprises. Viptela's Singtel deal is the first public insight into what the company is doing, which is to create a managed, SD-WAN service for large service providers.

Viptela officials have told me that similar projects are underway with other Tier 1 service providers. Service providers are interested in SD-WAN technology because it allows them to deploy managed routing, application delivery, and VPN services much more quickly, using software.

Singtel confirmed this in the press release, saying that giving customers more control over the network was a driver of the deal.

Customers "will have real time control over network issues such as performance, bandwidth utilisation and security," said Mr Lee Han Kheng, Vice President of Global Products at Singtel Group Enterprise, in a press statement.

Deals with global, Tier 1 service providers are not easy to swing, so this customer announcement makes Viptela one of the leading players in the SD-WAN market. It's also clear that companies that help service providers roll out managed services in the cloud become very valuable. A great example is what happend to Virtela, which developed one of the earlier software-based managed VPN services and was acquired by NTT for $525 million in 2013.