Performance evaluation the guaranteed quality of service on IP networks of DiffServ model

We present an overview about the model of differentiated services on the Internet according to the IETF recommendation. In the first section, we analyze the requirements of guaranteed Quality of Service of applications in general and of the realtime application in particular. Presented an overview about assurance quality of services on the IP network. Learning the model of differentiated services DS. Nowadays, performance evaluation is one of the most important fields of Information Technology. Evaluation of test results model of of differentiated services for guaranteed Quality of Service through using the network simulation system NS.