Layer 4+ switching with QoS support for RTP and HTTP

This paper provides an overview over current approaches and applications of layer 4 switching (L4Sw) and outlines a scheme for QoS support based on layer 4 and higher layer information. Today, L4Sw is mainly used for filtering in the context of firewalls. Additionally L4Sw has the potential of introducing per flow QoS support without the need for complex out-of-band signaling. We used traffic measurements on a real router to determine which higher layer protocols generate the most traffic and should therefore be investigated first. From the measurements it is obvious, that HTTP is the most important candidate. Experiments on extracting TCP and HTTP information demonstrated the feasibility of Layer 4+ QoS support with respect to processing power and storage capacity demands of intermediate systems. In addition to the TCP-based HTTP protocol, future investigations will be done for RTP as a key protocol for multimedia traffic.