Passive and Active Monitoring on a High Performance Research Network.

Warren Matthews, Les Cottrell and Davide Salomoni
Stanford Linear Accelerator Center (SLAC)

The bold network challenges described in "Internet End-to-end Performance Monitoring for the High Energy and Nuclear Physics Community" presented at PAM 2000 have been tackled by the intrepid administrators and engineers providing the network services.

After less than a year, the BaBar collaboration has collected almost 100 million particle collision events in a database approaching 165TB (Tera=10^12). Around 20TB has been exported via the Internet to the BaBar regional center at IN2P3 in Lyon, France, for processing and around 40 TB of simulated events have been imported to SLAC from Lawrence Livermore National Laboratory (LLNL).

An unforseen challenge has arisen due to recent events and highlighted security concerns at DoE funded labs. New rules and regulations suggest it is only a matter of time before many active performance measurements may not be possible between many sites. Yet, at the same time, the importance of understanding every aspect of the network and eradicating packet loss for high throughput data transfers has become apparent. Work at SLAC to employ passive monitoring using netflow and OC3MON is underway and techniques to supplement and possibly replace the active measurements are being considered.

This paper will detail the special needs and traffic characterisation of a remarkable research project, and how the networking hurdles have been resolved (or not!) to achieve the required high data throughput. Results from active and passive measurements will be compared, and methods for achieving high throughput and the effect on the network will be assessed along with tools that directly measure throughput and applications used to actually transfer data.