Subject: Re: Default site-local behavior for routers

From: Richard Carlson <[email-masked]>
Date: Fri, 01 Nov 2002 09:31:30 -0600

I disagree with this assessment.  In the v4 world sites that are, 
voluntarily or forcibly, using RFC 1918 address do expect to connect into 
the public Internet.  They do so because these are the only IP addresses 
they have, so what other choice do they have?

The multi-address space in the v6 world is being presented in a different 
light.  SLs are NOT replacements for RFC 1918 private addresses, they are 
just another option that a site can use if it chooses to.  SLs have no 
meaning outside the site boundary, just as LLs have no meaning outside the 
local link and Globals have no meaning outside the global v6 
Internet.  Therefore it is not possible for 2 disjoint sites to connect to 
each other.

The options to solve this should include getting globals or creating a new 
super-site that encompasses the individual sites.  The pressure to deploy 
NATs will only come if we fail to provide these alternatives.

Rich

At 04:24 PM 10/31/02 -0500, Keith Moore wrote:
> > are we looking for a way to
> > support applications that span multiple sites that each use site-local
> > addresses?
>
>the reality is that if SLs are widely used in v6 networks, apps will
>be expected to span sites using SLs, just as they are now expected
>to span between the public internet and sites using RFC 1918 addresses,
>and sometimes between multiple sites using RFC 1918 addresses.
>
>today that tends to require either that all nodes on private networks
>maintain an open connection to a point-of-contact in the public
>network, and/or that there be appliation-specific proxies at points
>where the various realms meet.  and it often requires a fair amount
>of complexity in the app due to lack of a usable global address space
>and the need to do routing through such proxies.
>
>Keith
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Richard A. Carlson                              e-mail: [email-masked]
Network Research Section                        phone:  (630) 252-7289
Argonne National Laboratory                     fax:    (630) 252-4021
9700 Cass Ave. S.
Argonne,  IL 60439

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---

From: Keith Moore <[email-masked]>
Date: Fri, 01 Nov 2002 10:47:16 -0500

> In the v4 world sites that are,

for that matter, what other choice do they have using the current
address allocation strategies for IPv6?   at least in v4 it was
once possible to get provider-independent addresses (I've heard it
still is possible - though they come at a high price)  In v6 we're
currently *insisting* on provider-based addresses, making addresses
in some ways even more difficult for private sites to get than
in IPv4.  I understand why this was done, but with current address 
allocation rules there may be at least as much pressure to use SLs 
in IPv6 as there is to use 1918 addresses in IPv4.

If we were to change things so that sites could get a non-routable
provider-independent prefix with about the same ease as getting
a domain name *then* there would be less pressure to use SLs.  
 
> The pressure to deploy

I mostly agree - though NATs have also been sold as ways to avoid
renumbering and to provide (pseudo-) security and we need to show
that there are viable alternatve solutions for these problems also.

Keith

---

From: Kurt Erik Lindqvist <[email-masked]>
Date: Sat, 2 Nov 2002 16:33:33 +0100

> voluntarily or forcibly, using RFC 1918 address do expect to connect 
> into the public Internet.  They do so because these are the only IP 
> addresses they have, so what other choice do they have?

This is an effect of the current shortage of IPv4 addresses that IPv6 
is supposed to address. Remember that the Internet was doing just fine 
before RFC1918 as well.

>
> The multi-address space in the v6 world is being presented in a 
> different light.  SLs are NOT replacements for RFC 1918 private 
> addresses, they are just another option that a site can use if it 
> chooses to.  SLs have no meaning outside the site boundary, just as 
> LLs have no meaning outside the local link and Globals have no meaning 
> outside the global v6 Internet.  Therefore it is not possible for 2 
> disjoint sites to connect to each other.

I don't think anyone here disagrees with what you are saying. However, 
what you are describing is the way that RFC1918 have been (ab)used. The 
argument is over the effects of using site-locals/RFC1918 addresses. 
That people would use site-locals in the same way as they use RFC1918 
addresses today I don't think anyone questions.

>
> The options to solve this should include getting globals or creating a 
> new super-site that encompasses the individual sites.  The pressure to 
> deploy NATs will only come if we fail to provide these alternatives.

Agreed. Creating PI space will leave to growth of the routing table, 
which is a multi6-wg concern, and will also in a way destroy the 
aggregation intent with IPv6. It would however make site-locals more or 
less unnecessary.

Allowing site-locals will have people use them the same way as they use 
RFC1918 space and that will lead to problems with deploying new 
applications built on peer-to-peer.

I think the peer-to-peer principle is more important than the 
routing-table growth. The routing-table will grow anyway, so we need to 
address that problem as it is.

- kurtis -