In this work, mechanisms to improve multimedia transmission over Internet are investigated. At the application layer, some level of QoS provision, based in the content of the data is the subject of research. A second level in prioritisation is proposed, consisting of categorising the multimedia data packets into two categories critical and non-critical. Then packets that are non-critical will be dropped first when congestion situations occur, and the TCP/IP protocol is to be modified to avoid resending these packets. Currently if the network is congested, or avoiding congestion RED capable routers are in the path, some packets may be dropped; if HTTP/TCP protocol is controlling the transmission, the packet must be retransmitted; this retransmission does not take any consideration regarding the impact in the final result as the data being dropped may well be critical to the particular application.

The research involves the design and development of a Bridging unit (workstation in this case) where all the multimedia traffic in the LAN is relayed to and all packets from different applications are monitored and selectively marked as critical or non-critical. Purposely the LAN is congested and the different nodes (workstations) in the network are monitoring and filtering the traffic that is within the available bandwidth levels. The tool used in the Bridging unit is the Network Simulator version 2 [ns].