Subject: Re: I-D ACTION:draft-ietf-ipv6-unique-local-addr-08.txt

From: [email-masked] (Scott Bradner)
Date: Tue, 7 Dec 2004 08:29:40 -0500 (EST)

Brian sez:
> Bill, you could do that if the prefixes are *routed* but that is
> not going to be the case if the ULA spec is followed, except for
> private routing arrangements. Since the spec says they MUST NOT
> be globally routed, 

imo - much wishful thinking

also imo - this whole idea is a clear and present danger to the Internet
(assuming that IPv6 gets general deployment)

Scott

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From: Brian E Carpenter <[email-masked]>
Date: Tue, 07 Dec 2004 16:21:11 +0100

> imo - much wishful thinking

My point is simply that what we say about DNS should be compatible with
what we say about routing.

> (assuming that IPv6 gets general deployment)

I disagree. The risk of these non-aggregatable prefixes appearing
in the default-free BGP4 table in exchange for lots of money is the same
as the risk of *any* longer prefix from PA space doing so. The danger
exists as long as rich enterprises are willing to pay for routeability.
There are other things we are doing (renumbering procedures, multi6, the
NAP draft) to try and deflect this danger, but ULAs don't increase it.

    Brian

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From: [email-masked] (Scott Bradner)
Date: Tue, 7 Dec 2004 10:25:21 -0500 (EST)

> what we say about routing.

I agree with that

> NAP draft) to try and deflect this danger, but ULAs don't increase it.

we disagree - I think they are an "attractive nuisance" (to use a 
pseudo-legal term) and we (the IETF) will rue the day that we approve
this idea

Scott

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From: "Stephen Sprunk" <[email-masked]>
Date: Tue, 7 Dec 2004 11:58:26 -0600

Thus spake "Brian E Carpenter" <[email-masked]>
> what we say about routing.

I think we must consider how little influence any RFC has on operational 
behavior, as opposed to the much greater influence they have on 
implementations.

IMHO, the best we can say is ULAs SHOULD NOT be returned in DNS responses to 
hosts that cannot reach those addresses and then give some guidelines on how 
to do this correctly in practice.

> NAP draft) to try and deflect this danger, but ULAs don't increase it.

I'll note that ARIN is, at this very moment, debating whether to allow PI 
assignments directly to end sites; if that proposal is approved, they will 
pay only $100/yr for a prefix that any ISP can be reasonably expected to 
accept.  The costs, in both time and effort, of getting every relevant ISP 
in the world to accept PA or ULA routes will be significantly higher.

S

Stephen Sprunk         "God does not play dice."  --Albert Einstein
CCIE #3723         "God is an inveterate gambler, and He throws the
K5SSS        dice at every possible opportunity." --Stephen Hawking

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From: Bob Hinden <[email-masked]>
Date: Tue, 07 Dec 2004 14:48:02 -0800

Scott,

>pseudo-legal term) and we (the IETF) will rue the day that we approve

I don't agree.

One reason I think this is not a significant concern is that the ULA 
prefixes are too long.  /48's aren't big enough for large 
organizations.  They will want a shorter prefix if they are going to go to 
the trouble of "convincing" their ISPs to route them for general usage 
(instead of using a PA prefix).  Instead of getting their ISPs to route a 
/48 ULA prefix, I think it is much more likely that they will do what 
people do today.  They will become a member of an RIR, and then become an 
LIR and get a PI prefix.  This is fairly common as I understand it.

If there is a need in the community for PI addresses that can be used by 
large organizations, then the RIRs should address that need directly and 
provide them.  It's not that hard for organizations to become an LIR today, 
so the RIRs might as well make the rules clearer and allow organizations to 
get these assignments without having to become a member of the RIR.

The underlying concern with this is, of course, the size of the default 
free routing tables and the stability of BGP.  ULA's aren't going to make 
this worse (or better).  Organizations that really need PI addresses will 
get them and then get ISPs to advertise them (as they do today).  It 
doesn't matter if the entry in routing table is a RIR assigned prefix, a 
ULA prefix, or something else.  It's still one entry in the routing table 
and routing updates.  The problem is a real one and is not created by the 
IETF standardizing ULA addresses.  Their intended usage if for local 
addresses (hence their name) and most people think they are an improvement 
over site-local addresses.

Bob

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From: Bill Manning <[email-masked]>
Date: Tue, 7 Dec 2004 17:54:55 -0500

On Dec 7, 2004, at 12:58, Stephen Sprunk wrote:

> I think we must consider how little influence any RFC has on 
> operational behavior, as opposed to the much greater influence they 
> have on implementations.
>
> IMHO, the best we can say is ULAs SHOULD NOT be returned in DNS 
> responses to hosts that cannot reach those addresses and then give 
> some guidelines on how to do this correctly in practice.

	and how are you going to determine the "reachability" between the two 
endpoints based on a name/address lookup?
	are you nuts?  the DNS has zero idea of the topology between the node 
making the query and the node information the query
	is requesting.

--bill

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From: Brian E Carpenter <[email-masked]>
Date: Wed, 08 Dec 2004 10:25:51 +0100

Stephen Sprunk wrote:
...
> I'll note that ARIN is, at this very moment, debating whether to allow 
> PI assignments directly to end sites; if that proposal is approved, they 
> will pay only $100/yr for a prefix that any ISP can be reasonably 
> expected to accept.  The costs, in both time and effort, of getting 
> every relevant ISP in the world to accept PA or ULA routes will be 
> significantly higher.

Not quite that simple. Firstly those "PI" prefxes would in fact be taken
out of PA space, because that's all the registries have today. Secondly they
would only be for people already allocated an AS number, and the registries
estimate that about 10k prefixes would be the maximum in practice.
However, you're correct that this would provide a much more attractive
safety valve than inappropriate use of ULAs.

    Brian