The Big Squeeze

Sean Donelan SEAN at SDG.DRA.COM
Tue Mar 4 04:30:51 UTC 1997

>Computational power required for a route flap is not the issue here.
>Many people have stated that, statistically longer prefixes flap
>more.  Unfortunately, they have then said that because of this shorter
>prefixes should have looser dampening parameters put on them, when
>what they really meant was that the longer prefixes should have more
>strict dampening parameters put on them.  Yes it is exactly the same
>thing, but it is an important semantic distinction.  If a group of
>prefixes categorized by a its length tends to flap more than the
>average, then said group should have more strict dampening parameters
>placed on it.

Statistics are soo much fun.

>From a single data point on my router, /24's currently account for 64% of
the routing table entries and for 65% of the flapping prefixes.  /16's
account for 12% of the routing table entries, and 10% of the flapping
prefixes.  It doesn't appear to me there is a significant difference
between flap behaivor of long prefixes and short prefixes.  There are
more long prefixes than short prefixes.  But as a group they both tend
to flap the same proportion of 2% of the routes within the group.
Sean Donelan, Data Research Associates, Inc, St. Louis, MO
  Affiliation given for identification not representation

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