system reduces training costs. A traffic management system also provides the more usual benefits that are derived from any effective network management software functionality. These benefits are that increased customer confidence and usage leads to higher revenues reduced customer churn decreases associated revenue loss higher call completion rates result in increased revenues. These are often mentioned in the marketing literature of OSS vendors. Often, traffic management functionality is not entirely built into the OSS. Rather, a performance or fault management OSS module relies upon a hardware-based traffic management device. However, we include this chapter owing to the integral importance of traffic management to achieve the aims of OSS software, however traffic management functionality is provided. K. Misra et al. (eds.), OSS for Telecom Networks © Springer-Verlag London Limited 2004 OSS for Telecom Networks 13.2 What is Traffic Management? All traffic management systems must monitor network traffic. However, they differ in the way in which they act, when they act and how they act. The most common time to act is when a pre-configured threshold is reached, triggering an alarm. The system will then apply controls to optimise traffic flow, and possibly re-route it. The idea is to detect a network problem before it impacts a service - and this will be the mandate of a network manager as far as traffic management is concerned. Real-time QoS alarms provide an exception-based mechanism to alert service providers of potential problems. When a (pre-defined) threshold is reached or crossed, the resulting alarm provides an early warning for a potential network prob- lem. Ideally, a threshold should be set to warn of a potential problem so that the problem is avoidable with advance notice to network engineering staff. An exception will induce the network manager to use traffic controls to modify the network state. Commands can be sent to the network elements individually or can be sent in groups. In addition, they can b