This paper addresses some issues related to the performances and feasi
bility of an interconnection optical bus for switching boards into lar
ge ATM switches. After providing a survey of several solutions to inte
rconnect switching boards, the study presents the advantages of an int
erconnection by means of a bus. This solution makes it possible to inc
rease the capacity of these switches in terms of global throughput (i.
e. number of 155 or 622 Mb/s input/output ports). At the same time, we
analyze the advantages of an optical bus for transmission and broadca
st of ATM cells between switching boards. This article shows that a sh
ared bus. used in the BSS switch element, provides a good solution for
interconnecting an arbitrary number of cards, by optimizing the numbe
r of input ports. For this switching element architecture, the study o
f the interconnection shows that this solution yields better performan
ces than the usual Clos network interconnection. (C) 1998 Elsevier Sci
ence B.V.