SD-WAN Over Global Private Networks

April 9th, 2018 by · 1 Comment

This Industry Viewpoint was contributed by David W Wang

As SD-WAN entering mainstream network services, people often think it as an innovative solution riding over the public Internet, bidding farewell to the private networks like MPLS traverses on. In reality this is not always the case. A recent event on SD-WAN reminds us of a different approach SD-WAN can take on its services.

Last week, an US California HQed SD-WAN service provider Aryaka Networks announced that it will partner with China Mobile International (CMI) to deliver a global SD-WAN service, targeting multinational businesses with locations in China as well as Chinese companies that have a global presence.

In the long list of SD-WAN service providers, Aryaka differentiates itself with it being able to deliver SD-WAN and network optimization via its own “global private network”, which to date serves over 7,000 sites in 63 countries across it.

As we mostly know of, one of the killer features of SD-WAN is to ride on an overlay of the public Internet, which can save tons of cost bypassing the traditional WAN technologies like private MPLS service, and also offer a robust performance for direct cloud access and applications.

However, while the overlay-based SD-WAN may be an answer for US local and regional deployments, it is hardly the answer for global WAN requests, with the reason being the underlay still has to leverage the public Internet or a hybrid scenario that includes both the public Internet and MPLS links for specific applications.

Here is the problem: from the global standpoint, the performance and availability of public Internet to date vary drastically from country to country, and region to region and its quality, especially in terms of network latency and packet loss, can easily run out of control.

For instance, from San Jose to Shanghai: the latency measurement for public Internet is 3.97 seconds, while private network only 0.306 seconds. In addition, packet loss often ranges from 10-15% over the Internet between branch offices located in San Jose and China, which results in data having to be sent through the network over and over again.

This would make a huge difference for enterprise users who need to transfer some large in size, time sensitive, cloud-based, and mission-critical workloads like ERP app- SAP By Design or As a rule of thumb, around 0.3 second of network latency is technically acceptable to most of business digital applications nowadays, while anything over 2% packet loss over a period of time is a strong indicator of problems.

In another instance of testing, using public Internet connectivity, application response time transferring file between Dubai and Dallas was between 0.75 to 2 seconds, and a different route testing for the same locations has resulted in between 0.127 to 4 seconds. Such performance variation and inconsistency for the network underlay, apparently can’t serve the business class SD-WAN successfully.

Aryaka claims that in order to solve this underlay network bottleneck causing global application delivery issues via the public Internet, they have built up a global private network for its SD-WAN that provides the flexibility of the public Internet and the reliability of MPLS. The private network not only provides secure access to data and applications from the corporate data center, but also to any cloud and SaaS environment.

For the local access leg, Aryaka’s model seemingly is to partner with different regional and local ISPs. In the China Mobile International case, for example, CMI will sell SD-WAN to Chinese enterprises and also local circuits for a complete solution. One popular local solution is to use dual Internet access. For much less money than MPLS, end user can support each location with at least two Internet pipes like 50Mbps or 100Mbps or more at their choice running to different POPs. Via such “dual Internet local access” customer enjoys more redundancy, better bandwidth and full support.

Something that we haven’t heard Aryaka touting much is the overall cost associated with its SD-WAN service. We may assume it would cost somewhere between the overlay network-based SD-WAN and private MPLS. After all, business customer nowadays would be willing to pay some premium for global SD-WAN services that run over private networks with dual Internet local access but still being cheaper than using a traditional MPLS solution.

Another example is Google. For more than 10 years, Google has been building its own private network infrastructure to support new, effectively real-time services that span the globe. About three years ago, Google launched Espresso – the fourth part of its SDN strategy, extending its SDN approach to the peering edge of the network — where it allows Google to balance traffic based on actual performance data and to react in real-time to failures and congestion, as well as to separate the logic and control of traffic management from the individual router boxes.

All in all, next generation WAN solutions would boil down to some tradeoffs amid network performance, business applications, and service costs associated. Aryaka’s approach seems to be positioning itself well and providing a sound SD-WAN solution in the global scale, and Google via SDN can exercise more control of the network flow and security. We expect the use of private networks to be the future for the global long-haul SD-WAN solutions.

David W Wang is a telecom/IT business development principal and senior consultant with ITCom Global, LLC based in Washington DC metro. In recent years his firm has successfully assisted enterprises and organization of various verticals in adopting and deploying SD-WAN services. Mr. Wang is also the author of the new book “Cash in on Cloud Computing”, and he can be contacted at

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