The Expanding Perimeter
In the same way endpoints are proliferating, so are the networks to which these devices connect. Just a few years ago, the corporate network and the home network were the predominant connection points. Today people often connect to multiple networks over the span of a few hours. We wake up and check our work email on the home broadband network; we do a little work at the local coffee house via guest Wi-Fi; we tap into the enterprise network when we arrive on-site at work; we switch to another guest network at the airport, even on the airplane. And, (gasp!) perhaps we even glance at email while stopped at a light over 4G wireless.
All of these networks add a new layer of complexity to the attack surface. To provide adequate security across all of them, what's needed is location-agnostic security technology that follows the user across his or her daily journey, wherever that might be. You need a unified, seamless blanket of protection.