Transparency in the SD-WAN Network

Most SD-WAN systems provide more visibility and analysis capabilities than basic routers and switches. This can be a curse as much as a blessing. The SD-WAN environment can precisely track and report latency and packet loss. While this data is good to help understand what happened in a particular incident or identify network behavior patterns for analysis, the temptation to fix specific instances of problems that are transient by nature can be counterproductive. At the same time, for chronic issues or as a means to gather intelligence related to a business change, the data available with most SD-WAN solutions is absolutely critical.

With the knowledge of how public data networks are built, network operators can identify real problems by using the data to address critical issues.

A Single ISP for at Least One Circuit
at Every Site is Best

SD-WAN devices can only prioritize the transmission of traffic into the WAN. The WAN implementation determines the priority at every hop between sites. Traffic that traverses multiple ISPs will not get the benefit of Class of Service within the WAN, so all traffic will be treated as best effort.

Using the same ISP at every site can create an MPLS-like experience between the sites. In fact, many carriers provide the same SLAs for two on-net internet circuits as they do for MPLS circuits. Certain ISPs allow for end-to-end class of service between internet circuits, and in most cases, the routes with the lowest latency are likely to be using the same ISP at both sites.

Finally, be careful that the ISP is using the same network ASN for all sites. Carriers may have multiple networks through acquisition that are not integrated. Without a common ASN, the benefits of a single carrier are nullified.

Always Favor Flexibility

As the SD-WAN capabilities improve and business needs change, the SD-WAN network must keep pace—sometimes even before the SD-WAN is fully implemented. Last-minute changes in requirements or network demands may be uncovered as the implementation progresses. External events such as a change in an organization’s remote work policy could substantially change the environment as well. While some platforms and licenses have more attractive prices, changes and modifications could be limited in the agreement. It's important to thoroughly understand your ability to make modifications and the flexibility of working arrangements, particularly within the SLA.

The WAN Will Continue to Evolve with SD-WAN

Wide area networking has evolved from point-to-point to IP to MPLS and now to SD-WAN. Each step in the evolution has become more integrated with the LAN and the broader technology environment of the enterprise. Such integration is necessary for more intelligent routing, management of critical applications and, ultimately, optimization of the user experience. SD-WAN integration requires an increasingly comprehensive set of considerations to assure that the correct problems are solved efficiently, economically, securely, and flexibly—and, most importantly, without disruption of enterprise operations.