Designing PI controllers for TCP/IPv6 networks supporting differentiated QoS requirements LiYunqiu YangShuang-Hua 2009 This paper presents a set of controllers for TCP/IPv6 networks. These controllers are developed from the traditional Proportional Integral Controller, and can support differentiated Quality of Service Requirement of the end users. Those requirements are labeled in the IPv6 header of the packets, checked by the controllers upon their arrival to the routers, so as to provide guidance to further dropping actions when congestions occur. Simulation results demonstrate the controllers’ ability of guaranteeing certain levels of Quality of Service to the end users according to their demands.