An empirical study of today's Internet traffic for differentiated services IP QoS

The IETF is currently focused on differentiated services (Diffserv) as the architecture to provide quality of service in IP networks (IP-QoS). The Diffserv architecture consists of two key components: traffic conditioning at the edge and per hop behaviour (PHB) at the core. Traffic conditioners are realized through various building blocks such as classifier, meter, marker, policer, etc. This paper focuses on an empirical study of pre-Diffserv Internet traffic. We use the results of the study to understand design choices for some of the Diffserv architecture building blocks. The primary contribution is an investigation into the usage of the type-of-service (TOS) field marking to understand if its usage justifies the IETF Diffserv Working Groups (WGs) standardization of class selector PHB on the basis of backwards compatibility with the TOS octet. A second contribution is a detailed examination of Internet and intranet traffic traces to understand issues related to packet classification in Diffserv edge routers. In particular, we study the need for classifiers that maintain per-flow state and utilize techniques based on inspection of layer-7 header/payload.