The expected traffic growth from new broadband services will require n
etwork capacities that can be beneficially provided by optical WDM tra
nsport networks. Optical packet techniques are essential for large net
works to provide flexibility and granularity. A layered network archit
ecture with a transparent optical layer and optical packet layers has
been elaborated. Four switching concept options for large optical ATM
switch fabrics in the public network and small access nodes are presen
ted. The technology for the related key functions of space and wavelen
gth switching was developed in the RACE ATMOS project and the feasibil
ity of concepts and technologies was verified in four system demonstra
tors.