Rand: Rate network dependability according to how humans, and not hardware, see it

Incorporating user perceptions into a network dependability measurement framework results in a more accurate picture than when data comes only from traditional sources, says a new Rand research paper.

Rand produced the paper at the behest of the Navy's Program Executive Office for Command, Control, Communications, Computers and Intelligence (PEO C4I). As the military grows increasingly dependent on networks, their dependability is vital, the paper notes.

The study criticizes a measurement of network operational availability arrived at through dividing uptime by the amount of time a network is both working and not working. A simple binary concept of network availability misses times of partial functionality, such as when a network is congested or partially degraded.

What's more, human failures--as opposed in particular to hardware failures, which is a traditional source of data in network dependability measurement frameworks--count for more than half of failures in networked environments, the Rand study states, citing other studies.

Availability isn't, therefore, dependent just on whether the hardware or other network components are fully functional. Rather, it can be measured as percentage of successfully executed service requests made during a certain time period, the study states.

Directly modeling the availability of a service is easier said than done, it adds. It would require diagramming all the hardware and software, as well as human interaction.

As for measuring sailor perception, Rand recommends that the Navy come up with a standardized way for sailors to report availability or reliability-related issues, since otherwise that perception-based information is not easily accessible nor comparable across systems.  

For More:
- download the Rand report, "Navy Network Dependability: Models, Metrics and Tools." (.pdf)

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