it/s in each direction, IPTV service with standard definition (SD) quality requires up to 3 Mbit/s reserved bitrate (with traffic shaping of the video flow) per piece of end-user equipment (e.g. IPTV user equipment, such as a setup box), and there is 10 Mbit/s per second overall in the downlink direction, then there can be a maximum of three pieces of IPTV user equipment connected, with the aim of guaranteeing QoS for the IPTV. Also, more 2.5 Traffic Management Techniques bandwidth dedicated to IPTV will result in less bandwidth (bitrate) in the downlink direction for the Internet access service. On the other side, services and applications offered through the Internet access services are not subject to admission control due to the network neutrality principle for the public Internet, and hence there is no admission control for the number of flows that can be established over it (e.g. a user can open different videos even in different browser tabs, and when the available bandwidth is consumed it will result in congestion, which will cause videos to freeze at a certain time period or constantly). Overall, admission control is directly related to QoS provisioning per flow or per traffic class (where a class denotes traffic aggregated from many flows from the same traffic type carried over the same links or networks). 2.5.5 Traffic Management Versus Network Capacity The extent and complexity of traffic management are associated with how much con- gestion is being experienced or how close network traffic is to the limit of the network's capacity, as given in Figure 2.10. When traffic demand is much lower than the installed network capacity, there is no need for intervention. When there is moderate "space" between demand and available network capacity, simple traffic management is needed, which includes bandwidth allo- cation and packet prioritization. When traffic demand approaches network capacity, the probability of traffic congestion increases significantly. In that case, traffic management is strongly required to