The WAN as initially conceived was about one simple job: the WAN was the network that “connects my sites to each other.” That is, the network connecting users in corporate sites to corporate IT resources in other corporate sites or perhaps colocation facilities. It was all inside-to-inside traffic.
Over the past decade so much has changed that, just before COVID-19 work-from-home mandates took hold, only about 37% of a typical WAN’s traffic was still inside-to-inside, according to Nemertes’ “Next Generation Networks Research Study 2020-2021”.