Re: Actions to quiet the Smurf amplifiers?

[Phil Howard <phil () whistler intur net>]

> If you search on the Cisco web page, you'll probably find it
> under "reverse-path" or "reverse-path forwarding" - only works
> for singly homed customers.

Then it is merely similar, and not identical, to what I described.
What I described included the notion that the source address must
be in the set of all (not just the best) routes back.  The theory
on this is that even most asymmetric routing will have a lesser route
that would be symmetric.  Of course some really goofed assymetric
routes do often appear and those may be trouble.

Still, the place where ISPs should apply it is all the interfaces
_other_ _than_ their border interfaces.  They will have control over
their own routing symmetry (hopefully) and the logic (at least as
I describe it) applies to packets coming _in_ on an interface, not
those going out.

-- 
 --    *-----------------------------*      Phil Howard KA9WGN       *    --
  --   | Inturnet, Inc.              | Director of Internet Services |   --
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    -- *-----------------------------*      philh at intur.net       * --