An Investigation into Transport Protocols and Data Transport ...

2.5. Summary 39
data, the most important metric will be to obtain high throughput in order
to maximise return on investment. Associated with this will be the need to
maximise throughput by sustaining a low overhead as retransmissions will
reduce goodput. As there will be no competing traffic on dedicated circuits
the order of importance of the metrics is the same throughout all Tiers.
If the dedicated link were to be shared between a few network users (e.g.
parallel streams, or simultaneous replication of data to a few sites across the
same dedicated network 1 ), then the sharing of the throughput between the
flows is important. As such, fairness and to a lesser degree, the convergence
times become a factor.
2.5 Summary
An outline of the methods and data rates of particle physics experiments,
such as the LHC were given. The ATLAS experiment was presented and
the MONARC hierarchy was discussed. In particular, the conservatively estimated
data rates required for the replication and analysis of such data is
expected to be at least an order of a magnitude greater than current experiments.
As such, the idea of Hybrid networks was presented in order
to facilitate high transfer rates between Tiered sites, yet maintain segregation
between flows in order to prevent/reduce the impact upon commodity
Internet Traffic.
The relative importance of various evaluation metrics were also presented
within the LHC application and four unique areas were identified.
1 Due to the continued development of reliable multicast, the HEP community does not
currently consider it as a viable option.