Evaluation of the TCP traffic over the ABR service targeted to support mass storage applications

Abstract

This paper discusses the performance of mass storage applications, that is, backup sessions, over ATM, being serviced by multiple available bit rate (ABR) connections. In particular, the undertaken work has assumed simultaneous ABR connections in the presence of competitive traffic in the network. More precisely, we have (a) evaluated the performance of multiple ABR connections end-to-end, using both the explicit forward congestion indication (EFCI) and explicit rate (ER) mechanisms, (b) studied the adaptation of the ABR sources under the presence of competitive traffic in the network by applying a dynamic fairness scheme and, (c) studied the dynamics and performance of the TCP/IP protocol over the ABR service specified for an ATM network. Moreover, the performance improvement of TCP over ABR, using an "interworking" function between the TCP end-to-end flow control and the ABR rate-based control as well as examine the effect of the "use-it-or-lose-it" function, is considered. Furthermore, the different levels of performance are compared so as to select the optimum values for mandatory ABR service parameters, being the maximum number of cells (Nrm) between two successive resource management (RM) cells and the factors controlling the increase/decrease of the cell transmission rate (RIF: rate increase factor, RDF: rate decrease factor). Finally, the concept of a dynamic UPC mechanism that monitors the ABR traffic contract is identified.