The model grows up Complexity at the core Elegant and intermingled The name game The Entended Enterprise Model

Now that the majority of corporate America is neck deep in e-business, network executives are beginning to move their companies into the next phase. They are building infrastructures that are tightly integrated with systems from those once labeled as "outsiders."

These organizations are no longer paying lip service to a unified structure while building Webified technology silos (separate Web, e-commerce, intranet and extranet sites). Rather, they are creating an environment where digital streams converge from all of a business's constituents: local employees, remote workers, road warriors, customers, the sales channel, suppliers and other partners. Business services based on a person's role - customer, employee, supplier - are the emphasis, rather than IT services developed to fit a person's physical location.

The model grows up

Extended enterprises - which go by many names - let constituents work in real time across heterogeneous environments, and across public and private networks, to get needed information to the right person or application. While architectural details vary from company to company, a generic conceptual model of the extended enterprise has begun to emerge. This model shows a big architectural shift (and more complex design) from the hub-and-spoke model of the mainframe or the three tiers of client/server (on which early e-business systems, too, were modeled).

Imagine a dartboard. As our interactive diagram illustrates, core IT resources, such as hardware, mission-critical software and data, go in the bull's-eye, while e-business-related applications for customers, partners and roving employees reside in the next ring. A security perimeter meant to restrict access protects each ring. Public data or consumer applications, if a company has any, go in a third ring. A security perimeter also protects this ring, although it is less rigid than the perimeters for the inner rings because its goal is to protect content, not to restrict access. Applications residing in the e-business or public layers might call on data and network connections in the core, should they have the security authority to do so. Users rely on the gamut of network connections to access their areas of the extended enterprise.