Sprint's filtering

Thu Oct 8 19:52:28 UTC 1998

Patrick Gilmore wrote:

| Sean and Sprint still act publicly as if they are guardians of the route
| table and without their wisdom and restraint, the rest of us would all die

On the contrary, Sean has always maintained that the filtering
was put in place to protect Sprint's customers from growth -- long-term
or instant -- in the global routing system.

The filters are an intelligent self-defence against misconfiguration,
whether diffuse (across many ISPs) or localized (e.g. UUNET's de-aggregation).

Limiting the number of prefixes one listens to must be done arbitrarily;
one could draw the line in many different ways, and the way I chose was
to draw it at the 18-bit level in what was then as-yet-unallocated 
address space.   Moreover, when experience showed that when the filters
were imposed people were actually using some of that address space,
the filters were relaxed across that space.  Even further, when, after
vigorous discussion with several registries, it turned out that filtering
anything longer than 18 bits was perhaps too harsh, the filters were 
further relaxed to something very much like what is in place now.

That people other than Sprint and its immediate customers might benefit
from a decision to limit the number of prefixes Sprint could hear from
its non-customers was always a secondary motivation.

Is there any particular reason why you keep banging on this drum this way?
I don't understand why you are so frequently so thoroughly UNPLEASANT
in your tone whenever you return to the issue, and I don't understand
why you return to the issue with such frequency.   Perhaps you might
pause to reflect on that before people write you off entirely as a wingnut,
and miss the occasional useful point you make (e.g., why isn't everyone
filtering?) and the occasional useful response made in reply (e.g., 
Sprint is not the only network filtering at the /19 level across newer
address space).

	Sean.