Dimensioning criteria of traffic contract parameters and Connection Admission Control rules in an ATM User-Network Interface

In the process of bringing ATM traffic control into reality, the ATM Forum has proposed to adopt the Sustainable Cell Rate (SCR) and its Cell Delay Variation Tolerance (CDVTSCR) as traffic descriptors, besides the Peak Cell Rate (PCR) and the Cell Delay Variation Tolerance for the PCR (CDVTPCR). The introduction of the SCR and the CDVTSCR aims at obtaining a more efficient multiplexing of source traffic streams than PCR can provide. The choice of the SCR, CDVTSCR, PCR and CDVTPCR values should achieve a (ideally optimal) compromise between the user required Quality of Service and the assigned resource cost. The aim of the paper is to provide guidelines for the choice of the SCR and CDVTSCR values. First, we evaluate the impact of specific SCR and CDVTSCR values on the Usage Parameter Control (UPC) performance in case of measured MPEG and LAN traffic. Then, CAC rules at an access multiplexer are derived by assuming that the input source streams are characterized by the traffic descriptors SCR and CDVTSCR; the impact of the values of SCR and CDVTSCR on the access multiplexer dimensioning is highlighted. A main result is the definition of conservative resource allocation rules that are easily implementable and yield guaranteed performance. Besides, a detailed analysis is carried out to obtain less conservative and more efficient allocation rules.