ABSTRACT
The topology of an enterprise architecture can be conceived as consisting of horizontal and vertical services. Traditionally, communication networks have focused on the concept of only horizontally layered services, for instance the ISO/OSI model (see Chapter 1), or vertical layering only, primarily due to end-to-end connectivity needs. But, from quality of service (QoS) and level of service perspectives, it is important to understand service interactions and relationships in two dimensions: horizontal and vertical.
