Business Requirements Drive Technical Requirements

Enterprises face many technical challenges when attempting to fulfill the requirements described so far, including the following:

• Guarantee total privacy between groups

• Assign users to their appropriate group based on some sort of authentication

• Enforce independent security policies for each group

• Enable secure collaboration mechanisms between groups

• Provide basic networking services for the different groups

• Provide independent routing domains and address spaces to each group

• Provide group extensibility over the WAN

• Implement billing and accounting mechanisms for each group

• Enforce the previous policies regardless of the physical location of the user in the network

Many technologies could be used to solve the problems listed; some are perceived as simple, whereas others are perceived as complex. Different business requirements will call for different degrees of connectivity and a different subset of the functionality described previously. Fulfilling the subsets of functionality will in turn demand varying degrees of technological sophistication. In general, an overlap of diverse business drivers will result in increased technological sophistication. For simple business requirements, simple technologies suffice. As the requirements become more complex or numerous, however, simple technologies cease to scale or even provide adequate connectivity.

A simple example of how business requirements drive the use of different technologies can be seen when we compare the connectivity requirements for simple guest access against the connectivity needed when supporting a secure service area. Guest access requires many-to-one connectivity (many guests to one Internet access point), whereas a secure service area will most likely require any-to-any connectivity. When providing many-to-one connectivity, the technology used could be as simple as access control lists (ACLs) or a mesh of tunnels that connect to a head end. However, providing any-to-any connectivity with either ACLs or a static mesh of tunnels is highly impractical. Therefore, more sophisticated virtual private networking (VPN) technologies, such as those discussed throughout this book, are necessary.