PERFORMANCE OF A CONNECTIONLESS PROTOCOL OVER ATM
Geert J. Heijenk
Aad P. A. van Moorsel
Ignas G. Niemegeers
University of Twente, Tele-Informatics and Open Systems
P.O.Box 217, 7500 AE Enschede, The Netherlands
tel. +31 53 893767; fax: +31 53 333815; e-mail: heijenk@cs.utwente.nl
Abstract
Recent studies show the existence of a demand for a
connectionless broadband service. In order to cope with this
demand, a connectionless protocol for the B-ISDN needs to be
designed. Such a protocol should make use of ATM and the
ATM Adaptation Layer. It needs to specify destination and
bandwidth of connections to the ATM network without
advance knowledge of the traffic that has to be transferred
over these connections. A possible mechanism which can cope
with this problem, the ‘On-demand Connection with Delayed
Release’ (OCDR) mechanism, is described. Its efficient
operation is based on the assumption that there exists a
certain correlation between subsequently arriving CL packets.
Two different arrival processes are used to evaluate the
performance of the OCDR mechanism: a Poisson arrival
process, and a Markov Modulated Poisson Process (MMPP)
which models a bursty traffic source. Markov models of the
OCDR mechanism have been constructed for both arrival
processes. For the model with Poisson arrivals, a closed form
solution is presented. The model with MMPP arrivals is
solved numerically.
Compared to a ‘Permanent Connection’ mechanism
significant bandwidth reductions can be obtained provided
that the offered traffic has a bursty nature. Furthermore, the
OCDR mechanism has the advantageous property that the
obtained average node delay is not strongly related to the
intensity and burstiness of the offered traffic.
1 Introduction
The Broadband ISDN (B-ISDN) is being designed in order
to satisfy the needs for more bandwidth and more flexibility in
public telecommunications in the coming decades. The Asyn-
chronous Transfer Mode (ATM) has been selected as the target
transfer mode for B-ISDN. ATM provides a connection
oriented (