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

Paul Vixie paul at vix.com
Wed Aug 1 23:39:51 EDT 2007

> ... yes, I do think this kind of thing will be self-correcting, for one
> simple reason: you don't have to know who's doing it to filter effectively.

i think you're being overly optimistic.

> All you need to know is what the minimum allocation size for each address
> range is.  (I know you know all this already, but I'm sure there are others
> who don't.)  A quick look at
> http://www.iana.org/assignments/ipv4-address-space and
> http://www.arin.net/reference/ip_blocks.html gives me a pretty good idea
> that I could filter, more or less safely, anything larger than /8 in the 0/8
> to 56/8 range (with a couple exceptions, like down to /20 in 24/8), down to
> /16 in the 128/8 to 172/8 range, down to /20 in the 63/8 to 99/8 range, etc.

i don't think it's anywhere near that simple.  also, even if you find a way
to express it, if others accept these routes and you don't, then your support
queue fills up and theirs does not, and perhaps customers leave you and go to

> If I were to implement such a policy, I'd first take a good hard look at my
> BGP table (rather than the cursory look I just did), but it's by no means
> necessary to identify the specific players doing the deaggregation in order
> to appropriately filter it.

ah, the irony.  i guess what went around came around?  internap used to be one
of the worst TE deaggregators.  welcome to concern about other folks'
deaggregation and global routing table size and shared fate.  <smirk>

> If my reading of history is correct (as it was mostly before my time), 
> we've been through something similar before, with a number of players 
> filtering down to minimum allocation size for many years before routers 
> caught back up with the size of the table and the filters became more of 
> a problem (affecting reachability of folks not advertising their 
> aggregate route) than they were worth.  But if we see a high level of 
> deaggregation of allocated netblocks (without a change in the underlying 
> IANA or RIR allocation), I suspect we'll see a return of these prefix 
> length filters.

they'll return, but relaxing them for one's customers will be common, and
relaxing them for peers in exchange for reflexive relaxation from peers will
be common.  recurring revenue is king.  "unfiltered" will be a competitive
advantage.  you cannot count on others doing the right thing for the internet
(or else i'd be able to count on you to deploy V6 right now as an incentive
to get others to do likewise since they could reach internap even on V6.)

ps. i am not speaking as an arin trustee in this message.

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