Quality of Service for IP Networks : In Theory and Practice

Abstract: Quality of Service (QoS) for IP networks is a set of methods for establishing better and more reliable performance for today's and tomorrow's networks. When transmitting real-time data from such applications as IP telephony, video conferencing and IP broadcasting, it is imperative that the data is transmitted quickly and with even delays. Longer delays mean problems when communicating, varying transfer times means that data packets are delivered too late to be used, or even dropped. As network applications grow more demanding, the networks can not always keep up. Even though a network may offer more bandwidth than needed, disturbances to sound and picture is to be expected because of the competition with other data traffic. QoS can solve many such problems by reserving private channels through a network, or differentiating classes of traffic to prioritise the sensitive data. QoS also contains methods to speed up backbone data transfers by in advance planning complete routes over a network, and avoiding congested or broken connections. This report explains QoS as it stands today, together with suggestions on how it could work for Axis Communications AB. It also presents an experiment to test some QoS methods in a real-time sensitive situation, demonstrating the effectiveness and priceworthiness of QoS.