Re: Why ULA: low collision chance (Was: IPv6 fc00::/7 — Unique local addresses)

Fri Oct 22 15:40:35 UTC 2010

On Oct 22, 2010, at 5:25 AM, William Herrin wrote:

> On Fri, Oct 22, 2010 at 1:20 AM, Joel Jaeggli <joelja at bogus.com> wrote:
>> On 10/21/10 6:38 PM, Owen DeLong wrote:
>>> On Oct 21, 2010, at 3:42 PM, Jack Bates wrote:
>>>> On 10/21/2010 5:27 PM, Joel Jaeggli wrote:
>>>>> 
>>>>> Announce your gua and then blackhole it and monitor your prefix.
>>>>> you can tell if you're leaking. it's generally pretty hard to
>>>>> tell if you're leaking rfc 1918 since your advertisement may well
>>>>> work depending on the filters of your peers but not very far.
>>>> 
>>>> This is always the argument I hear from corporate customers
>>>> concerning wanting NAT. If  mistake is made, the RFC 1918 space
>>>> isn't routable. They often desire the same out of v6 for that
>>>> reason alone.
>> 
>> the rfc 1918 space is being routed inside almost all your adjacent
>> networks, so if their ingress filtering is working as expected, great,
>> but you're only a filter away from leaking.
> 
> A filter away from leaking to -one- of the millions of entities on the
> internet. Two filters away from leaking to two.
> 
This underestimates the transitive property of leakage.

Owen