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Software-defined WAN -- perhaps the most publicized business service offering to come along in a decade -- is facing an almost universal dilemma. As is usually the case with new technology, the early and easy business cases for SD-WAN are based on a few main features.
As the market develops, SD-WAN will either have to find new avenues for feature differentiation or become a commodity offering, differentiated only by price. Those avenues for feature differentiation are thus the key to a dynamic and expanding market.
The basic, existing SD-WAN feature
SD-WAN is a form of virtual private network. Unlike other VPN technologies, like Carrier Ethernet or IP and MPLS, SD-WAN creates connectivity by building an overlay network that can ride on top of any network technology, including and especially the internet.
Due to residential broadband advances, high-speed internet is available in most of the world and is comparatively low-cost. SD-WAN can then extend corporate VPNs to sites where MPLS is too expensive or simply not available. It can also bridge VPNs of different operators, which is a benefit to global businesses. The overlay VPN feature is the key to realizing this core SD-WAN benefit, so every SD-WAN option on the market provides it in some way.
Because overlay VPNs based on SD-WAN can be used to displace MPLS services and equipment in sites where the cost and benefit of MPLS are marginal, it posed a threat to both network operators and equipment vendors. This threat induced operators to offer their own SD-WAN service -- better to lose MPLS customers to your own service than to a competitor's -- and prompted router vendors to buy SD-WAN vendors and integrate their technology into edge routers.
The new SD-WAN offerings have driven SD-WAN adoption, but they also created a risk of their own. If every SD-WAN service and product has the same features, providers can differentiate their offerings only on price. Lower prices not only increase the threat SD-WAN poses for MPLS VPNs, but it reduces profits for everyone. The only alternative to price differentiation in a competitive market is feature differentiation, so it's hardly surprising there's a quiet movement to add features to basic SD-WAN.
1. Cloud-hosted SD-WAN nodes
The feature most often added to basic overlay SD-WAN today is a cloud-hosted SD-WAN node. You can't add hardware devices to a public cloud, but you can add a software version of an SD-WAN node to the cloud -- and with it add applications and components to your company VPN.
Public cloud computing is the hottest topic in IT, as SD-WAN is the hottest topic in networking, so these cloud nodes build value by developing both trends. Today, nearly all SD-WAN services and products offer at least some form of cloud-hosted node capability.
2. Traffic and connection management
The second most popular SD-WAN feature is traffic management. Because an SD-WAN node sits between an office's users and its network connection, SD-WAN can prioritize traffic by user, application or both. This can improve overall quality of experience for users by giving time-critical applications preferred connectivity. Other existing network tools can also provide this capability, however, so it's not as enduring a competitive benefit as the cloud node feature.
Connection management is related to traffic management. Some SD-WAN products provide the ability to support multiple network paths -- routes through a network like the internet -- multiple network providers or even a combination of network technologies, like the internet plus MPLS. These can improve the performance and reliability of SD-WAN connections. But the more advanced multiprovider features will also add to SD-WAN's cost, so the number of sites and buyers that adopt connection management is limited.
3. Explicit connectivity management and NaaS
The final SD-WAN feature option is rare today: explicit connectivity management and network as a service. SD-WAN nodes, like any network service on-ramp, are effectively edge routers that direct traffic onto paths to the correct SD-WAN node to reach the destination. Because SD-WAN is aware of each connection, it can manage connectivity explicitly. This feature set is the leading edge of SD-WAN feature differentiation, and it will likely be the focus for product and service evolution for years to come.
IP networks traditionally support implicit connectivity -- for example, if you have the address of something, you can send a packet there. Security consists of introducing barriers to connections you don't want to happen, usually through firewalls. If connections have to be explicitly allowed, you don't need to block connections you don't want -- just don't enable them in the first place. That could revolutionize connection security.
Explicit connectivity control is also essential for effective virtual networking. Network addresses point to service access points -- not users or applications. So, if something or someone moves, the address changes. With explicit connectivity control, the address of something can be made to point to where the something really is at the moment -- and that's the way virtual networks have to work.
More SD-WAN features mean better competition
Competition is the answer to why these new SD-WAN features will end up emerging.
Enterprises that use SD-WAN products can create SD-WAN services. SD-WAN services can be purchased from managed service providers, at least a few of which use self-developed technology to provide the services. Your network operator is almost certainly either offering SD-WAN already or planning to, and competitive network operators are surely available if you want SD-WAN from an operator source other than your own. All these possible channels compete both within the channel and between channels -- and nobody wants a price war.
The most important thing about SD-WAN feature differentiation may be its effect will be to separate service from network in a more decisive way. New features are realizing the idealized network-as-a-service vision the industry has chased for a decade, making networks as virtual as the cloud and independent of infrastructure. These changes may finally free operators to optimize network technology in an orderly way, while sustaining and enhancing services -- and that's critical for their revenue future.