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[RRG] Route Flap Damping parameters
Hello,
I have been
following the discussion about BGP path hunting ('[RRG] BGP path hunting, MRAI
timer and Path Length Damping') on this list with some interest. With Route Flap
Damping (RFD) being a possible factor in the observed behavior, I had
some questions about determining values for its configurable
parameters (Suppression threshold, Reuse threshold, Time-to-half amplitude, and
Maximum suppression time).
I understand that
prior to the recommendation made in RIPE-378 to not use RFD, RIPE-229 made
recommendations about configurable parameter settings. In reading RIPE-229, it
seems the recommendations were not strongly based on observations of actual
dynamics (although I could be dead wrong on this since I'm not familiar with all
the work that lead to the creation of RIPE-229). As well, from reading
a selection of papers on the subject of RFD preventing timely convergence,
there doesn't seem to be an analysis of what might happen if RFD parameter
sets other than the common defaults were applied, nor does there appear to
be a history of literature on this subject. My reading in this area
has been by no means exhaustive, so my questions are: has there been any
work done on determining what the impact of other sets of RFD parameters might
be; how have (or might) such sets be chosen; have the dynamical properties of
the RFD algorithm been worked out - with a view towards assessing whether
they would even be potentially capable of improving observed dynamics? I
have been thinking about these areas, but wasn't sure if it had all been done
before and these were dumb questions.
Cheers,
Jim.