Stage of Service
A stage of service is comprised of a contention point, and one or more queuing points. The notion dates to ATM network equipment design systems and reflects a general purpose way to visualize and describe the components in a router or switch. Contention points are the "intersections", where traffic from different sources contend for an output to a destination. Star, bus, cross-bar, and other "backplane" network equipment designs are examples of contention points in the x-TCA platforms as well as proprietary hardware based systems. Queuing points are a component of a stage of service which hold packets prior to or following contention points. Stages of service each have their own characteristic delay and packet loss behavior. Unmediated bottlenecks can be effectively exploited within their stages of service by malicious or non-standard congestion control such as those found in newer versions of TCP.