Meeting Quality of Service (QoS) objectives in Internet Protocol (IP)-based networks has been a challenge since the birth of IP protocols. But IP is no doubt the most rapidly growing telecommunication technology. There is a growing trend toward putting every single type of traffic in IP format. Voice over IP (VoIP) is not a new concept. Efforts are on the way to carry real-time video traffic using IP instead of Asynchronous Transfer Mode (ATM) or Integrated System Digital Network (ISDN). The transportation radar data over IP clouds is another target to achieve. So the real challenge is to use the IP but keep the qualities of these applications similar to the quality of Circuit Switched Networks.

Degradation in IP quality occurs mainly due to two reasons: (i) When IP packets don't have bandwidth available at a node, they are queued and delayed. Resources needed for IP traffic consist mainly of bandwidth and buffer space. (ii) When bandwidth is available, but improper scheduling of packets causes packets to be queued and delayed.

Hence, if we put intelligence in resource reservation as well as in scheduling mechanisms, this QoS problem can be solved. In order to accomplish this goal, we have developed a scheme in which we adapt resources as well as scheduling priorities of QoS. The scheduling priorities and resources are adapted on the basis of end-to-end (ETE) delay. Our control mechanism adapts scheduling priorities and resources so that ETE delays of QoS sessions are minimized in the order of their required ETE delays, whereas ETE delays for non-QoS sessions are unconstrained.

The scheme we developed assigns initial set of priorities to each new QoS session on the basis of its ETE delay requirements and network congestion conditions. If with this set of priorities, packets of new QoS session can reach their destination without violating their ETE delay requirements, then these priorities are considered optimal and are not changed. However, if the ETE delay objectives of the QoS session are not met, the scheduling or serving priorities of the QoS session are adapted by a feedback mechanism. Feedback from the destination node passes ETE delay information to all the nodes along the route of the QoS session. As a result, every node adapts the serving priorities of the QoS session to control its ETE delay. Hence by adapting the scheduling priorities, we control ETE delays and hence the quality of the QoS sessions.