[ppml] alternative realities (was PIv6 for legacy holders (/wRSA + efficient use))

Paul Vixie paul at vix.com
Wed Aug 1 19:46:26 EDT 2007

scott wrote, answering my "is there policy work to do?" question:

> Let's say that a legacy /8 holder like MIT decides to start leasing out 
> their IP space to "customers" buying a tunnel, dial-up, or some other 
> similar form of connectivity.  Let's say there is sufficient demand for 
> IP space that they sign up a number of customers, each receiving a /24 
> with their tunnel and announcing it in BGP to their upstreams.  Now 
> let's say this kind of behavior causes the routing table to explode.  If 
> I'm a DFZ operator who is no longer able to handle all these prefixes, 
> my solution is pretty simple: stop accepting /24's carved up out of /8 
> allocations.  Doing so would cause me to send traffic to MIT's customers 
> via the MIT /8.  That in turn would either mean that the traffic would 
> hit MIT's network and then get sent to MIT's customers via their tunnel, 
> or it would hit an intermediate network that was listening to the 
> more-specific /24 announcement from MIT's customers (probably because 
> they're being paid to do so), who would in turn send the traffic along 
> normally.
> In summary, I'm sure this kind of thing will happen as we exhaust the 
> IPv4 free pool, but I'm not sure it will break things too badly.

i am less sure that this kind of thing will happen in /8-land.  the actors
are too large and too bright and too visible.  in /16-land, where it's much
harder for you to tell the players without a scorecard, and where scorecards
could be lawsuit magnets, it could be prevalent.  if it happens often enough
using enough different /16's then you might have trouble figuring out what
to filter, especially if it changes every day, and the list gets long.  are
you prepared to say that this problem will be self-correcting and that the
routing system will remain stable under that sort of growth?  i'm not.  i'm
also not sure what to do about it.  but someone who thinks it would be bad
should try to propose some policy to make it better, i'd like to read that.

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