November 8-10, 1991 - Klofas.com

composition of the file server traffic, for example, the five
concurrent uplink users could be doing mostly file upload
transactions. Furthermore, the extra uplink traffic could easily
reduce response time which, in turn, would result in reduced
overall traffic rate.
SUMMARY
Construction of an accurate model of PACSAT-l operations
based solely on the statistics which can be extracted from
monitored downlink traffic is not an easy task. However, while
there is still room for improvement of the simulation model, the
results have been encouraging. Further work is being done to
reduce the differences between statistics computed from actual
data and those produced by the simulator for file server traffic.
While making the changes, attention will have to be given to the
possible effects of recent changes to the file server and file
broadcasting software aboard the satellite. Namely, allowing
hole lists to be broadcast and lengthening of the broadcast frame
data field from 139 to 255 bytes. The user traffic patterns wi11
be re-examined to see if there have been any significant changes
since the first analysis.
REFERENCES
1. Diersing, R.J., "Characterization of PACSAT-l Traffic
Via Downlink Monitoring," Proc. ARRL 10th Computer Networking
Conference, to appear.
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