Title: Measurements on Dierentiation of Internet Trac Tekijä: Osasto: Professuuri: S-38 Tietoverkkotekniikka Valvoja: Ohjaaja

The use of real-time applications in the packet networks is setting new requirements for the packet delivery. The current best-eort model in the Internet does not facilitate control over important characteristics such as delay, jitter and packet loss, which is needed for the proper operation of applications with real-time requirements. The main focus during the last years on providing QoS in IP networks has been in the area of the Dierentiated Services (DiServ) architecture. DiServ provides the necessary tools for implementing better service to the Internet in a scalable way. Scalability is an essential requirement for all Internet services. DiServ is a framework that describes the main components and mechanisms for realizing QoS. The framework gives quite a lot of freedom for how the implementation is done and what are the dierentiation principles. This has created a lot of research and arguments about how the DiServ network should be actually implemented. This thesis studies the dierentiation issues in the DiServ network. Dier-entiation in this work is based on the idea of separating trac with dierent characteristics (e.g. UDP and TCP) into distinct forwarding classes. The rst part of this work presents the motivation for application based dierentiation and describes the DiServ architecture as well as some other ways of providing QoS in the Internet. Also two well known DiServ implementations for general purpose PC hardware will be presented. The last part of this work presents measurements that we have conducted in an isolated DiServ network using ALTQ as the QoS engine. ALTQ/CBQ is used to provide a class based isolation among dierent trac types. luokkapohjainen eriyttäminen eri liikennetyyppien välillä.