Subject: Re: ULA (was Re: ARIN Board Advises Internet Community on Migration to IPv6)

From: Fred Baker <[email-masked]>
Date: Tue, 22 May 2007 10:41:53 -0700

On May 22, 2007, at 10:02 AM, Jason Schiller wrote:
> How exactly should someone make a portion of their IPv6 allocation  
> not routed?

You have identified a number of ways to go about it.

> 3. Get the RIR to give out more than one allocation per org.

A centrally-managed ULA differs from a centrally managed prefix of  
any other type in a pretty small way - it matches a certain filter.  
In any other sense, it is a second allocation to the administration  
in question, nothing more and nothing less.

> Guaranteeing the uniqueness of the address space used internnally  
> is essential.

I understand the point that "a high probability of uniqueness"  
differs from "unique".

Actually, if it were me, I might do it yet another way. I might  
advertise everything within my domain and advertise my entire /48, / 
30, or whatever outside my domain, and in the edge routers null route  
the CIDR block(s) that I was keeping private. If the address space is  
centrally managed,and as a result the address space I am using  
internally is known in other domains, I don't see any reason to  
depend on neighboring routing systems to protect me in their routing.

My point is not "bzzt - bad idea". My point is "I see some issues".  
I'd like to have a reasonable discussion of the issues. OK with you?