[arin-ppml] ARIN Draft Policy 2011-5: Shared Transition Space

Chris Grundemann cgrundemann at gmail.com
Wed Jul 6 14:56:18 EDT 2011

Thanks Bill, we will work to include your input in the next version of the I-D.


On Tue, Jul 5, 2011 at 15:01, William Herrin <bill at herrin.us> wrote:
> On Tue, Jul 5, 2011 at 3:57 PM, Chris Grundemann <cgrundemann at gmail.com> wrote:
>> In response to the IAB statement regarding ARIN-2011-5, several of us
>> have compiled an Internet Draft analyzing the need for shared
>> transition space. You can find it online here:
>> http://tools.ietf.org/html/draft-bdgks-arin-shared-transition-space.
> Thanks Chris, and everybody else who worked on this!
> Some comments:
> 1. In 2.1.3, SP services is not a good use case. Quasi-multihoming
> with a NAT box switching traffic between two separately numbered
> Internet connections is becoming increasingly common. With a /10,
> there's a very small chance of collision between the address assigned
> on each connection, but with services hosted on that /10 that the
> customer wants to reach, the chance of mayhem rises sharply.
> 2. Router interface numbering is a potential use case. Filtering of
> RFC1918 is too widespread to overcome, so using it outside the NAT
> breaks path MTU detection. That's not inherently true of this new
> space and nonfiltering could be encouraged in a way that renders it
> usable in a few years.
> 3. In 2.2.2 there's another conflict risk. Consider:
> ISP uses:
> Customer directly connects a Windows PC. Assigned by DHCP.
> Customer connects Cisco VPN client (UDP tunneled IPSec) to work at
> Work uses
> www.intranet.work is at
> Uh oh.
> 4. In 4.1.2, common getaddrinfo() implementations follow RFC 3483 rule
> 7's requirement to prefer native transports. As a result, the 6to4
> destination address is tried last (behind IPv4), further mitigating
> effects from incorrect 6to4 instantiation behind a firewall that
> obstructs its function.
> Regards,
> Bill Herrin
> --
> William D. Herrin ................ herrin at dirtside.com  bill at herrin.us
> 3005 Crane Dr. ...................... Web: <http://bill.herrin.us/>
> Falls Church, VA 22042-3004


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