Whole generations of applications have been developed around various computing models, each with its own requirements for network support. In the good old days of host computing, applications required minimal bandwidth and were relatively time sensitive, and traffic flows were deterministic between dumb terminals and the mainframe. Capacity planning involved designing efficient topologies, scaling switches, and sizing trunk lines. These were relatively straightforward problems, since the application environment was stable and user requirements were well understood.

As networks evolved toward interconnected LANs supporting the client/server model, planning became more difficult. Client/server applications were much more bandwidth intensive and extremely time-sensitive. Traffic flows were distributed across the entire network, although they were relatively deterministic. Network managers faced the more complex challenge of defining a hierarchy and ensuring that traffic flowed across it, but deterministic traffic flows aided in the development of applications that successfully addressed business needs.

The intranet model is the latest step in the evolution of enterprise networks to a peer-to-peer computing paradigm. The advent of the corporate intranet is replacing traditional client/server applications with new concepts of information sharing and Web navigation. Emerging intranet applications are both bandwidth-intensive and time-sensitive, often requiring support for voice, video, and data multimedia applications across a common infrastructure. These applications can be deployed by individual workgroups in an unstructured manner without centralized planning. This results in peer-to-peer flows that are much
less deterministic than traditional client/server applications while consuming unpredictable amounts of bandwidth.

The corporate intranet model places new demands on the networking infrastructure:

• Intranets provide their user community with access 24 hours a day, 7 days a week.

• Intranets require immediate connectivity to any local or remote site in the world.

• Intranet users expect instant access to information without restriction.

The term intranet is broadly used to describe the application of Internet technologies within a private corporate computing environment. Intranets take advantage of the large family of open standards protocols and multi-platform support (desktops to mainframes) that have emerged from the Internet to more effectively share information across the enterprise. The goal is to seamlessly link the organization’s workforce and information to make employees more productive and information more widely available.