[ntp:hackers] Mitigation rules

David Mills mills at udel.edu
Mon Apr 6 17:02:31 UTC 2009


NASA/JPL has decided to implement the NTP interleaved modes for Mars 
orbiters and deep space missions. These modes are implemented in the 
current development verion. This requires some rethink on the mitigation 
rules and prefer peer concepts as the intervals between updates can be 
significantly longer than the current engineering model. After some 
thought I have revised the mitigation rules to support such things as 
multiple prefer peers, multiple PPS sources and engineered fallback 
should all sources fail. The revised rules are intended to cover the 
existing GPS/PPS paradigm, sole PPS source and other more or less 
bizarre hookups. The revised rules are at 
www.eecis.udel.edu/~mills/ntp/http/prefer.html. They are in fact 
implemented in the current development version, which should in almost 
all cases be backwards compatible with previous versions..


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