Christophe Mangin

Accelerated Signalling for the Internet over ATM (ASIA)

To face up the rapid development of Internet services with even more growing needs in terms of quality of service and bandwidth, we introduce in this paper an accelerated signalling capability for the ATM network. As a preliminary, we draw attention to the fact that cell spacing can regulate the dynamics of TCP over ATM if the spacing period is adequately chosen. Then, we propose to associate with each Internet information flow (generated by TCP or UDP) a Deterministic Bit Rate (DBR) virtual channel connection within the ATM network. The cell spacing mechanism actually makes the cell stream of an Internet information flow compliant with a DBR connection, for which quality of service objectives in terms of negligible cell loss and bounded cell transfer delays can be guaranteed. To achieve this, we study a synchronization method between the two connection establishment procedures, namely that at the Internet protocol level and the signalling procedure for the ATM network. The ATM connection is established throughout the network via a light-weight signalling procedure, which relies on the exchange of single cell messages consisting of Resource Management (RM) cells. The addressing system proposed for this accelerated signalling capability is that of classical IP, which is and will certainly be the predominant one in the near future.

Analysis of Cell Spacing on a TCP Flow Mapped onto an ATM Connection

We show in this paper that the cell spacing technique can be used to regulate TCP when the traffic of a TCP connection is carried over an ATM connection. For this purpose, we consider a very simple traffic configuration where two workstations exchange TCP data traffic segmented into ATM cells and transmitted over an ATM link traversing a cell spacer. We precisely analyze how the buffer content of the cell spacer evolves over time. The results obtained via very simple mathematical models are then compared with those of a real TCP data transfer experiment.