> Margaret Wasserman wrote:
> Do you really think that it is realistic to just tell
> everyone to use provider-assigned addresses throughout
> their network?

No. Scores won't buy it. Let's not forget that one of the reasons behind the 
considerable success of NAT, despite its huge annoyances, it because NAT does provide 
some of the PI perks. PA is good for dial-up users and home/soho setups. Bigger, you 
find NAT, because for many the no-sweat ISP switch is worth more than the NAT-induced 
problems.

In my experience, the number one reason for going to RFC1918/NAT is an ISP change. The 
ISP pulls out of a market or tanks, the customer looks at my proposal for renumbering, 
chokes at the bottom line, and says "make sure we don't have to go through this again 
next time the ISP bellies up". Welcome to NAT.

Having two of the tier-1 ISPs in bankruptcy does not help this feeling.


> We've been getting feedback from network administrators that
> they need a form of local addressing that allows their
> internal numbering, firewall configuration, etc. to be
> independent of their ISP-provided addresses.

Network administrators want three things:

1. Local, private addresses that do not communicate outside of their site. Site-locals 
are perfect for this, if they are not limited to disconnected sites.

2. Unique addresses that do not need public Internet access but do need to communicate 
with selected external sites (example customer/supplier VPN). This is GUPI.

3. Global network layer PI identifiers. Although this is not directly linked to the 
multihoming issue, it is likely that a scalable multihoming solution would provide it.

I do not envision a large-scale deployment of IPv6 without providing all three. Also, 
it would be a hell of a good idea if 2. could migrate to 3.


> It is my belief that if we ignore this problem, and simply
> limit site-locals to disconnected networks (a la RFC 1918
> addresses), then IPv6 NAT will arise to allow sites to
> separate internal addressing from external addressing.

Agreed. And we should not underestimate the danger of this, as there is a lot of 
working v4 NAT code out there and transforming v4 NAT code into v6 NAT code is a lot 
less work that writing NAT from scratch 5 years ago. Most of the ALGs issues have been 
sorted out already.


> What we really need is a better way to solve this problem,
> one that doesn't have the problems of site-local addresses.
> And, that's why we're discussing GUPI addresses.

Agreed. Unfortunately, one of the main issues with GUPI addresses is managing the risk 
they end up being a mess in the global routing table, � la IPv4 swamp. So far, the 
lack of a multihoming solution has been a strong enough disincentive to kill GUPI 
attempts in the egg before they were even born.

Any GUPI proposal will have to address this.

Michel.

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