An enterprise network is an interconnected collection of LANs, computers, and peripheral devices (e.g., printers and disks) designed to meet the overall computing needs of a corporation. The enterprise network could be small with a few LANs interconnected within one building, or it could be a massive network spanning the globe and including hundreds of LANs and thousands of computers.
Applications are distributed over a number of different locations and a variety of computing platforms, including PCs, workstations, minicomputers, and mainframes. Historically there were a number of different protocols used to communicate. With the advent of the almost universal adoption of IP, interconnection of these disparate systems has become almost seamless and the typical enterprise network now includes the Internet playing a significant role in its WAN. By doing this the data is far more available, which can be a double edged sword.
The corporate network in the 21st century is undergoing a remarkable metamorphosis. From the hacked-together network of yesteryear, the modern corporate network is drawing on a smaller set of stable network technologies to build ever larger networks supporting an ever wider array of network applications and services, including voice and video services. However, we can still break the corporate network into distinguishable pieces worth examination.
In fact, we can generally talk about four different kinds of networks in the corporate enterprise network: the LAN, the storage area network (SAN), the metropolitan area network (MAN), and the WAN. Although there is no clear technological distinction among these networks any longer, we can generally distinguish them by their scale, the most commonly used technologies, the ownership of the facilities and equipment, and the purposes for which the networks are most likely used.