SD-WANs were created in large part to overcome the high cost and inflexibility of MPLS and private data services. To achieve that goal, the SD-WAN must minimally connect sites to existing MPLS services as well as to Internet services, such as xDSL or cable. Ideally, 4G/LTE connectivity should be offered as well.

 

But businesses today need to connect more than just physical locations. Resources have moved to the cloud and so must the SD-WAN. This means locating an SD-WAN node within or as close to the IaaS or SaaS datacenter as possible. Deploying physical edge appliances into the cloud datacenter is difficult if not impossible. Even knowing where to deploy a virtual SD-WAN appliance can be difficult, requiring IT to map the subnets of their data assets to their physical location. Only then a premises be leased or built to position the SD-WAN appliance.

 

SD-WAN as a Service may avoid these issues by positioning PoPs near or within the same exchange points connecting to IaaS and SaaS cloud network services. But much depends on the geographic footprint of the service. The PoP needs to be within 25 milliseconds of the cloud provider’s premises.

 

The same is true for mobile users. SD-WAN edge appliances generally do not support mobile users. SD-WAN as a Service offerings may support mobile users with a “lightweight” mobile client to establish a VPN into the SD-WAN service. The effectiveness of this approach will again depend on the geographic footprint of the service, as well as the service’s ability to secure and optimize mobile traffic.