RTnet, a new approach to in-home real-time multimedia communication
Hans Scholten, Pierre G. Jansen, F.T.Y. Hanssen, T. Hattink · University of Twente Research Information · 2002
streams, but variable-bit-rate streams can be mapped using several techniques [3]. The EDF scheduler is distributed over the nodes and the token is the place where the schedule is kept; nodes will keep backups of the schedule though. If a node has the token and it wants to add or remove a stream, it calculates a new schedule and acts upon it. Before a new stream may be added the node does an EDF feasibility test to determine if the newly added real-time stream will meet its deadlines without making other streams miss theirs. The EDF feasibility test is simple [4]: the total of bandwidth utilizations by all streams may not exceed 100%. However, only 80% of network bandwidth is dedicated to real-time (multimedia) communications, the rest is used for non-real-time purposes. Actually, the maximum bandwidth is slightly less because of the token transmission and Ethernet packet overhead. When the scheduler at the active node decides that another node must become active it stores the global s