[address-policy-wg] 2007-05 New Policy Proposal (IPv6 ULA-Central)

Jeroen Massar wrote:
> Tony Hain wrote:
> > Randomness could be a natural outcome if the default configuration for
> > SOHO routers was to create one and bury the ability to specify it
> > under some 'Advanced/Experts-only' option.
> >
> > There is a 'need' for this space to satisfy Enterprise network
> > managers that have external partnerships and are unwilling to deal
> > with collisions no matter how unlikely. While these organizations
> > could use their PI space for this, they don't want to because that
> > ends up impacting their internal routing due to the number of
> deaggregates that get announced.
> 
> Can you elaborate that last sentence? Do you mean that these people do
> not know that there is an 'aggregate' knob on their routers and that
> they will be deaggregating this prefix when announcing to the Internet?

No. Consider a global organization that has multiple suppliers/partners with
private interconnects for specific business functions. The goal is to
restrict the private interconnect to use for the specific task, not to leave
it open for all traffic between the organizations. To manage traffic they
deaggregate the partner network and announce the specific part for the
private link, and the aggregate via another path for the rest. The result is
2x entries for each partner.

This is avoided in IPv4 by using nat to create an artificial internal
aggregate leading to the edge where these partner networks are connected. By
using the central ULA (and more efficiently by carving that by region), they
can recreate this internal aggregate model while avoiding any possibility of
collision.

> 
> As I mentioned, we can't engineer around stupid people. The default of
> those routers should be to aggregate to resolve this 'problem'.
> 
> What is the difference between having:
>  2001:db8::/48 + fc00:db8:5678:1::/64 + fc00:db8:5678:2::/64
> and:
>  2001:db8::/48 + 2001:db8:5678:1::/64 + 2001:db8:5678:2::/64

Nothing. If they announce the full deaggregate for the ULA space the impact
would be the same as using PI deaggregates. The value is to have fc00:/8
lead to the demarcation for all the partners, rather than explicitly
announce every partner subnet throughout their own organization.

> 
> For both prefixes (excuse the ULA central bit) one would have to go to
> the registry to get it, and as one gets PI, one is already going there,
> why go there twice and claim 2x /48, which most likely is waaaaaay too
> much anyway.
> 
> Did I misunderstand something in your statement?
> 
> Greets,
>  Jeroen