On traffic consideration of the ATM multiplexer with priorities

The paper deals with the problem of priorities in the ATM military networks. The standard for the public network defines only two priorities operating on the cell level which are used to mark these cells which do not confirm the traffic contract; the marked cells are sent with low priority and can be discarded in the switch when congestion occurs. Additionally, the priorities can be implemented in the switch and as a consequence cells belonging to some connections can have a higher priority than other cells. The future ATM military networks will require one to implement an efficient priority scheme operating on the VP/VC connections. This is because in these networks there is a need to send data with different urgency. A common method to implement the priorities is to use the non-preemptive priority scheme. However, this can radically reduce the QOS (quality of service) corresponding to the connections with lower priorities and this effect is not always desirable. Therefore, this is a reason why we propose a different approach allowing one to control the QOS for the connections of lower priorities. More specifically, we propose an approach to control the priorities based on a cycle, i.e. cells with different priorities are stored in different queues and their access to the server is governed by the repeated access list. We distinguish two modes of operation, when the list is fixed and when it can be changed in adaptive way. The included numerical results show that the proposed methods allow us to control the QOS for the connections in the presence of priorities