The paper presents recent results corresponding to a new strategy for source traffic generating, named priority forcing scheme (PFS), allowing Internet users for getting better than best effort service in IP network. The concept of PFS assumes that an application, called PFS application, sends to the network a volume of additional traffic for the purpose of making the reservations for the data traffic in the overloaded router queues along the packet path in the IP network. The emitted redundant packets, named R-packets, should be rather of small size comparing to the data packets, named D-packets. The PFS scheme assumes that the R-packets waiting in a queue can be replaced by the arriving D-packets and belonging to the same flow. In this way, the D-packets can experience a prioritised service comparing to the packets produced by a non-PFS application. Notice that the proposed solution does not require any quality of service (QoS) mechanisms implemented in the network, like scheduler, dropping, marking etc., except R- and D-packets identification and replacing. We discuss the PFS efficiency for forcing priority in the overloaded conditions. Moreover simple system analysis is also presented. Finally, the profits of using PFS scheme are illustrated by examples corresponding to FTP (TCP controlled traffic) and VoIP (UDP streaming traffic) applications.
The paper presents trial experiments with IP QoS network services (NS) defined and implemented in the AQUILA pilot installation. The AQUILA NSs (premium CBR, premium VBR, premium multimedia and premium mission critical) provide a framework for supporting a variety of applications generating both streaming and elastic traffic. The measurement experiments confirm that AQUILA architecture differentiates the QoS offered to these NSs. The presented numerical results were obtained in the test network installed in the Polish Telecom (Warsaw) consisting of 8 CISCO routers.
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