The evolution of network connectivity over the years has been progressive, evolving from X.25, frame relay and...
asynchronous transfer mode to internet VPN and MPLS virtual private routed networks. Now, a huge amount of buzz surrounds software-defined WAN, and SD-WAN benefits are changing the network connectivity landscape.
The original thinking behind software-defined networking -- from which SD-WAN technology emerged -- was about the ability to support agnostic connectivity, in which a centralized management server sends instructions to a hardware edge device.
The reality is somewhat different in terms of connectivity. Most service providers market SD-WAN as a type of internet-based virtual private network (VPN). With the growing demand for cost savings, combined with flexibility, reporting and access to public cloud services, the adoption of SD-WAN over internet connections is growing significantly.
With this in mind, the connectivity landscape is again changing by making the internet a trusted delivery mechanism for secure data transmission. Where the internet was once a best-effort network, IT is beginning to view internet providers' public networks as scalable, traffic-engineered, low-cost delivery mechanisms for encrypted tunneling.
Hybrid networking aligns business requirements and connectivity
The future for services like MPLS, then, depends on the requirements for security and end-to-end traffic performance guarantees. With so many providers pushing SD-WAN as internet-based VPN services, MPLS will see a decline in usage, as IT teams view the platform as restrictive and expensive. The private nature of MPLS connections means an organization can access only certain cloud services, depending on whether it has connections to private cloud services in its data center or office locations.
But MPLS is the technology of choice when enterprises require end-to-end traffic performance and privacy. While internet-based SD-WAN benefits include granular traffic control for both prioritization and connection states, quality of service (QoS) exists primarily at the customer edge. With MPLS, end-to-end traffic prioritization is an inherent property of the technology that translates into predicable latency and jitter to support mission-critical and delay-sensitive applications.
The marketplace view is MPLS is no longer suitable for today's cloud requirements. Our desire to work remotely and with mobile devices, combined with a need to reduce costs, often precludes MPLS providers from connectivity discussions. While headquarters and medium to large branch-office locations benefit from predicable site-to-site performance, users can be restricted in their daily activities. Some IT teams are questioning the validity of today's private networks, because a single internet service provider (ISP) can offer the scalability they need.
The nature of always-on, feature-rich devices with software-based security and features is resulting in a natural shift toward internet-based connectivity. As ISPs grow their platform to cope with more traffic than ever before, the internet has matured into a serious contender to private MPLS networking.
The need to reduce complexity and costs drives the demand for SD-WAN. Even the mobile phone is, in many respects, a reason for SD-WAN adoption. If a single box or client is able to cost-effectively terminate any type of connectivity and apply granular security, the connectivity landscape is bound to change, because internet can be used with any SD-WAN device.
SD-WAN changes the global connectivity landscape
The global connectivity market is more of a challenge than national deployments. Providers push SD-WAN benefits like cost savings by procuring local broadband internet circuits, but organizations should pay careful attention to latency, jitter and support issues. Nationally, the use of multiple providers doesn't affect latency as much, because traffic traverses fewer hops across networks. In comparison, global organizations may experience more latency and jitter, because traffic can traverse multiple providers' networks worldwide.
In this respect, performance may be the largest risk for global organizations. The laws of physics can't be broken, even with granular QoS. Traffic from the U.S. to Asia or the U.K. is governed by the time it takes for packets to arrive. But organizations should also consider where they will get support for service issues. When using multiple ISPs for SD-WAN, for example, customers need to think about who will identify and troubleshoot issues, because having multiple providers means dealing with multiple contacts and departments.
The internet matures as a connectivity platform
In many respects, the job of IT and procurement teams is to ensure they obtain the details behind any SD-WAN proposition. While SD-WAN benefits and low-cost internet connections look good at a high level, successful implementations will require thought for support and traffic-routing issues.
Outside the MPLS vs. internet argument, the connectivity landscape is becoming more varied using SD-WAN capability. Organizations can install multiple connectivity types into one appliance, resulting in the device -- or, rather, the management service that comes with the device -- making decisions on where to send traffic depending on state.
In the past, status was often simply up or down. WANs are now able to sense when certain application traffic becomes untenable and can reroute it based on parameters like packet loss or high latency. With granular control at the packet inspection level, rerouting critical application traffic may only occur if failover bandwidth is low, which is another example of how SD-WAN is more than the next internet VPN.
SD-WAN as technology is here to stay, but enterprises must remember their own DIY or managed service implementations aren't all about the internet and cost savings. SD-WAN benefits and the technology's promise are remarkable whether you decide to hook up MPLS or broadband circuits.