Alternative traffic conditioning mechanisms for the virtual wire per-domain behavior

Interactive networked multimedia applications are sensitive to delay and jitter affecting the transmission of their data packets. Without the support of quality of service, the nature of the Internet makes it difficult to deliver data streams in the demanded constant and steady way these applications need for an acceptable performance. Because of this limitation, value-added services like the "virtual wire"-per-domain behavior (VW-PDB) impose the obligation of traffic conditioning mechanisms in the transmission path to assure a continuous data stream to an end user. However, each traffic conditioning action is a potential source for additional delays experienced by the processed data packets. In this paper we will show that the configuration suggested by the VW-PDB for traffic conditioners in a last hop router can quickly lead to unwanted significant additional delays. Although applications will then be served with a constant data stream with minimal jitter, the traffic conditioning might exceed their delay limitations. Since modern multimedia applications normally use their own playback buffers for jitter compensation, they do not depend on a complete jitter-free transmission, like the VW-PDB tries to establish by emulating a dedicated switched-circuit. Hence, two suggestions with more flexible reliable traffic conditioning mechanisms in the last-hop-router will be presented. Both approaches will be compared to the strict rules prescribed by the VW-PDB in terms of jitter compensation and additional delay.