Subject: RE: Draft on Globally Unique IPv6 Local Unicast Addresses

From: "Michel Py" <[email-masked]>
Date: Fri, 9 May 2003 15:15:52 -0700

Brian,

>> Michel Py wrote:
>> 1. We can't enforce router vendors to code the default
>> blackholes. Before moving ahead with this I would like
>> to hear clear signs from the players in the field that
>> they would support it.

> Brian E Carpenter wrote:
> Why is this different from FEC0::/10?

It has nothing to do with the prefix itself but with the scope. Here's
the scenario:

Site A wants to pervert globally unique site-local addresses (the
mechanism to make them globally unique such as a registry, random, MAC
address hash etc is not relevant here) into globally routable globally
unique addresses aka PI.

Site A pays all of its upstreams to announce its prefix in the global
routing table.

Site A wants to talk to site B.
Let's assume that nobody filters A's FEC0:x:y::/48 prefix between A and
B (which by your own account below could happen).

Site B receives site A's traffic. Some host at site B replies to site A.

The egress router at site B dumps the return traffic into the bit bucket
because the return address is scoped as site-local and the egress
interface is in the global scope (or some similar reason).

>> 2. We can't enforce operators to filter the prefix. I
>> dropped filters on my BGP feeds and from one of my peers
>> (a well-known player) I get all kinds of crud including
>> /64 routes, /48 routes, /41 routes, name it I get it.

> I think there will be Darwinian effects here, as we saw
> during the first years of CIDR. But yes, if someone pays
> enough, they will get their /64 announced. That will happen
> whatever we write in RFCs.

My point exactly. We can't rely on this alone.

>> The demand for PI is very strong. There are people that
>> would support it. The major concern I have with this draft
>> is that your original intent (remove ambiguity of private
>> addresses) which is good could easily be perverted into
>> global random PI which is terrible.

> Can you propose a solution to ambiguous local addresses that
> doesn't thave this risk?

Not without site-local addresses being part of the architecture. Can
you?

Michel.

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From: Brian E Carpenter <[email-masked]>
Date: Sun, 11 May 2003 13:03:06 +0200

Michel Py wrote:
> It has nothing to do with the prefix itself but with the scope. 

Of course. And why is the scope issue different, just because we
have removed the ambiguity?

   Brian

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From: Brian E Carpenter <[email-masked]>
Date: Sun, 11 May 2003 13:01:49 +0200

Michel Py wrote:
...
> My point exactly. We can't rely on this alone.

Now explain why it's a problem, if the customers pay enough
to cover the costs. 

   Brian