d a printer. They usually support virtual docking stations, peripheral sharing, and ad hoc infrared links. An increasing number of machine- to-machine (m2m) applications are emerging, as are applications involving wear- ables and even implants; their key benefits cannot be realized without PANs. In the case of wearables and implants, the PAN exists on, or even in, the person. In fact, when talking about wearables, some refer to fabric area networks (FANs), in which the network is embedded in the fabric a person wears. The Internet as Corporate Backbone Another trend, just beginning to emerge, is the disappearance of the corporate LAN. In areas of the world where bandwidth is plentiful and cheap, some forward- thinking organizations have begun shrinking their LANs and relying on the Inter- net to play the role of corporate backbone. These companies have migrated many Chapter 5 Data Communications Basics of their applications to Web-based services housed in (often outsourced) data cen- ters. The applications are owned and maintained by the corporation; all access is via Internet-connected Web browser and is authenticated against a corporate direc- tory server. These organizations no longer face the burden and expense of main- taining complicated corporate networks sprawling with various "extranets" and multilevel demilitarized zones (DMZs). The rise of high-speed ubiquitous Internet connections and reliable portable authentication has finally made such "deperime- terization" possible. Data Communications Traffic As the architecture of data networks has changed, SO have the applications people use, and as applications have changed, SO has the traffic on the network. This sec- tion talks about some of the most commonly used applications today and how much bandwidth they need, how sensitive they are to delay, where error control needs to be performed, and how well the applications can tolerate loss. The most pervasive, frequently used applications are Web surfing and e-mail. Various forms of Web applications have dram