  The Large Synoptic Survey Telescope (LSST) is a proposed 8.4-meter telescope
that will be located in the Andes mountains in Chile. Every 17 seconds, a 6.4
GB image is transferred to Illinois for immediate processing. That transfer
needs to complete within approximately five seconds. LSST is provisioning an
international WAN with a 10Gbps bandwidth guarantee for this and other
project-related data transfers. The stringent latency requirement drives a
re-examination of TCP congestion control for this use case. Specifically, prior
work on dedicated Long Fat Networks (LFNs) does not go far enough in fully
leveraging the opportunity provided by the bandwidth guarantee. This paper
presents an approach for how optimal network throughput can be obtained for the
LSST use case, and the conditions under which any project can achieve data
throughput rates on long-distance networks approaching wire speed.
