The Influence of ATM on Operating Systems
Jonathan M. Smith
CIS Department, University of Pennsylvania
The features of ATM offered many attractions to the application community, such as fine-grained multiplexing and
high-throughput links. These created considerable challenges for the O.S. designer, since a small protocol data unit
size (the 48 byte “cell”) and link bandwidths within a (binary) order of magnitude of memory bandwidths demanded
considerable rethinking of operating system structure.
Using an historical and personal perspective, this paper describes two aspects of that rethinking which I par-
ticipated in directly, namely, those of new event signalling and memory buffering schemes. Ideas and techniques
stemming from ATM network research influenced first research operating systems and then commercial operating
systems. The positive results of ATM networking, although indirect, have benefitted applications and systems far
beyond the original design goals.
The various technical contributions of the US “Gigabit Testbed” program[Computer 90] were both manifold and un-
dersold. Amongst the more significant contributions were those made in the AURORA Gigabit Testbed, which linked
Penn, Bellcore, IBM Research and MIT in the Northeast corridor of the United States [Clark 93]. While AURORA
experimented with two packet formats, “Packet Transfer Mode” (PTM) and “Asynchronous Transfer Mode” (ATM),
in retrospect the ATM-centric research had significantly more impact on modern operating system software.
It is is worthwhile to set the stage. While AURORA was initiated in 1990 under the HPCA (“Gore Bill”) the
research was actually kicked off at Penn and MIT in 1989 under Project DAWN, funded by Bellcore. The goal was
to build an integrated LAN/WAN infrastructure using an OC-48 SONET channel provided by Bell Atlantic, MCI
and Nynex. Using a clever OC-12 cross-connect topology devised by Dave Sincoskie of Bellcore, we were able to
concurrently operate PTM over SONET from Penn