was bogon filters, now "Brief Segue on 1918"

Joel Jaeggli joelja at bogus.com
Wed Aug 6 10:20:53 CDT 2008


Darden, Patrick S. wrote:
> Was looking over 1918 again, and for the record I have only run into one
> network that follows:
> 
>    "If two (or more) organizations follow the address allocation
>    specified in this document and then later wish to establish IP
>    connectivity with each other, then there is a risk that address
>    uniqueness would be violated.  To minimize the risk it is strongly
>    recommended that an organization using private IP addresses choose
>    *randomly* from the reserved pool of private addresses, when
> allocating
>    sub-blocks for its internal allocation."
> 
> I added the asterisks.
> 

You're supposed to choose ula-v6 /48 prefixs randomly as well... Any 
bets on whether that routinely happens?

While you're home can probably randomly allocate subnets out of a /8 or 
/12 for a while without collisions, nobody that's actually building a 
subnetting plan for a large private network is going to be able to get 
away with that in v4.

> --Patrick Darden
> 
> 
> -----Original Message-----
> From: Darden, Patrick S. 
> Sent: Wednesday, August 06, 2008 9:19 AM
> To: 'Leo Bicknell'; nanog at nanog.org
> Subject: RE: Is it time to abandon bogon prefix filters?
> 
> 
> 
> Yes.  1918 (10/8, 172.16/12, 192.168/16), D, E, reflective (outgoing
> mirroring), and as always individual discretion.
> 
> --Patrick Darden
>  
> 
> -----Original Message-----
> From: Leo Bicknell [mailto:bicknell at ufp.org]
> Sent: Wednesday, August 06, 2008 9:10 AM
> To: nanog at nanog.org
> Subject: Is it time to abandon bogon prefix filters?
> 
> 
> 
> "Bogon" filters made a lot of sense when most of the Internet was
> bogons.  Back when 5% of the IP space was allocated blocking the
> other 95% was an extremely useful endevour.  However, by the same
> logic as we get to 80-90% used, blocking the 20-10% unused is
> reaching diminishing returns; and at the same time the rate in which
> new blocks are allocated continues to increase causing more and
> more frequent updates.
> 
> Have bogon filters outlived their use?  Is it time to recommend people
> go to a simpler bogon filter (e.g. no 1918, Class D, Class E) that
> doesn't need to be updated as frequently?
> 





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