renumbering/multi-addressing [Re: Enforcing unreachability of sitelocal addresses]

[Pekka Savola <pekkas@netcore.fi>]

Hello,

I added multi6 on Cc: list for this particular piece of the thread.

On Sun, 26 Jan 2003, Margaret Wasserman wrote:
[...]
> Some folks have argued that easy renumbering would eliminate the need
> for enterprises to have provider-independent addressing, but I don't
> agree.  Addresses are stored in many places in the network besides
> the interfaces of routers and hosts, such as access control lists,
> configuration files, .hosts files, DNS configurations, ACL lists, etc.
> In many cases, addresses are stored in nodes on other subnets.  So,
> being able to renumber the interfaces of hosts and routers on a
> particular network or subnet doesn't even solve half of the problem.

There are multiple reasons why people want PI addresses.  Renumbering and
multi-addressing has multiple different models.  Some are easy and some
are very difficult.  We should develop at least the _easy_ solutions
because they are probably useful too.  For now, it's enough to manage the
first 80% of the problem.

Consider four reasons why people might want PI, routable addresses:

- "I don't want to be in problems if my ISP goes bankrupt!"
==> multiple addresses are just fine here (deploy them before the ISP 
goes down, but use only one set of them etc.)

- "I want to be able to change ISP's at will reasonably easily, to keep an 
edge"
==> multiple addresses are fine here too!

- "I want to be able to protect against failures in my link(s) to my ISP 
and problems in our router(s)"
==> multiple addresses can deal with that too, with some added glue!

- "I want to be able to protect against failures in my upstream ISP"
==> tough cookie, no solution here!

Get the picture?  Greedy folks want it all, but actually we _can_ provide
quite a bit of it already!
 
> Choices seem to be:
> 
>          (A) Continue with PA addressing, and accept that enterprises will
>                  use IPv6 NAT to get provider-independence.
>          (B) Allocate PI addresses, and trust that we can determine a
>                  scalable PI routing scheme before we hit route scaling
>                  issues in the IPv6 backbone.

I don't comment on these except that you seem to be making some 
conclusions I don't agree on.  I don't think PA equals IPv6 NAT, not at 
all.  There are solutions there.

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings