WAN virtualization combines two or more network connections of any type to create a single, virtual pipe between locations. This enables cost-efficient, high-availability, and high-bandwidth capacity. All aggregated links are active, and the full amount of bandwidth is always available. It can augment or replace expensive private MPLS circuits with low-cost broadband internet links and achieve excellent application performance and reliability, even with congestion events.
A well-designed WAN virtualization solution will perform dynamic, real-time traffic engineering. It will react subsecond, not only to link failures, but also to congestion-related network problems. WAN virtualization supports both session-based steering and per-packet traffic engineering. The advantage of per-packet traffic engineering is real-time reliability and predictability for all applications. WAN virtualization is more comprehensive than WAN link aggregation. It can easily handle connections with significant differences in bandwidth, latency, jitter, and packet loss. It will also determine where to steer traffic based on current, real-time conditions for each network connection.
WAN virtualization is a term that pre-dates SD-WAN, and has largely been replaced by that term, even though only a small number of today’s SD-WAN offerings deliver true WAN virtualization.