368 ◾ Enterprise Architecture A to Z
ese IP purists make the case that the following questions need to be answered before an
extension is advanced:
1. How many users need a given functionality?
2. What are users willing to pay for the functionality?
3. How much do different solutions cost?
Past attempts at extending the network layer have failed in the view of purists because each
approach tended to be a “big solution for a small problem,” and such solutions had a higher cost
than the corresponding saving. ere may be solutions that are “good enough,” without requir-
ing a systemwide upgrade of the Internet. ree examples can be considered to make the case: (1)
multicast, (2) QoS, and (3) traffic engineering.
e Integrated Services (intse