In a system with noncentralized control, your first objective after having established the profile of the application, its path through the network, and the pattern it leaves behind is to assign demarcation points for monitoring performance.
Demarcation points are strategic connection points in the conversation transmission. By observing specific conditions (metrics) at these points, you can gain a quick and inductive view of the application's performance. The demarcation points become the natural aggregators of an application's performance issues.
The collected metrics provide the background and data to assess when you have taken the optimization as far as possible within the confines of your control. They will then assist in reassigning responsibility or escalating requirements and issues to third-party organizations.
When assigning QoS protocols in a system with noncentralized control, consider the virtual boundaries imposed by the different areas of control (such as a carrier-controlled core network).