Subject: RE: Fwd: IPv6 Scoped Addresses and Routing Protocols

From: "Michel Py" <[email-masked]>
Date: Thu, 27 Jun 2002 15:35:07 -0700

kre,

>> Tony and I are proposing schemes that are aggregatable and
>> that are not tied to a provider.

> kre wrote:
> Both those schemes are geographic based addresses - these aggregate
> if and only if one assumes that areas that are geographically close
> are also topologically close.

This is absolutely untrue. I will let Tony defend his own, but for the
two different methods that ipv6mh is working on, there is no relation
whatsoever between the network/fiber plant topology and the geographical
aggregation.

> They're provider independent only of there are multiple providers
> that have agreed to cooperate with each other and share the
> prefix (essentially routing packets to each other when they arrive
> at the "wrong" place).

This is another wrong assumption. We know that asking ISPs to advertise
a geographical aggregate that contains competitor's addresses is not
going to fly. I would not do it myself. The solutions that we are
developing do _not_ require transporting competitor's traffic.

> While that is entirely possible to assume might happen in some
> high density usage parts of the world, where multiple providers
> can all exist and make a profit, in much of the world, the simply
> aren't enough active users to support the infrastructure for
> multiple providers.

We do not require any local infrastructure.

> Anyone would always be free to connect to a different provider,
> by simply connecting to a more distant location of course - but
> then their address would not (could not if any aggregation at all
> is to be achieved) be based upon their geography, but the
> provider's instead.  That is, to change providers an address
> change is likely to be required for many (perhaps most) and for
> those it isn't, the provider choice will be limited to those who
> have managed to join the local provider club.

True, but what if joining the local provider club is free? You would
have a point if being present at some kind of IX was required, but it's
not.

> On the other issue ... anyone can (attempt to) pay any ISP, or set
> of ISPs to carry any address.   The rish is certainly no greater of
> that happening with a SL address with a site-id embedded, than it is
> for a global address allocated by a different provider, or a
> geographic address from some other region.

A valid point. Please note that we are not claiming that geographical
addresses alone will solve all of the problems at once.

> If anything, the risk is less with SL addresses, as they can be
> clearly labelled "for local use only", lowering the chances that
> people will ever decide they would like to interpret them as global
> addresses (all of these things are just numbers, so perceptions,
> and what the ISPs will agree to do are all that matters anyway).
> Global addresses are expected to be globally visible, and there's
> no reason at all to assume that people won't go to a competitor
> ISP and say "I will connect to you, and pay you all these $'s if
> you will agree to advertise the prefix I have already been
> allocated this other way"

True enough. However, you forgot two important things:

1. If we make SLs with site IDs globally unique, there might be no
assignement (or the assignement might be automatically granted by the
addressing architecture, say a 37-bot hash of the MAC address, or
whatever). With the geographic scheme we are designing, there would
still be the need to go to a RIR and register a block, so we might still
decide that someone with a dial-up 28.8k modem does not qualify for a
portable, globally unique /48 block.

2. SLs do would not have a supporting protocol if used globally (how
could there be one, if they are not supposed to be used that way). The
way I see the geographical addresses is a support of the multihoming
protocol. And if there is a protocol, there can be safeties and policy
enforcement features built in.

> (and even say to ISPs, "I will connect > to you, and you allocate me
> an address, but you agree that once allocated you can never reclaim
> the address, no matter whether I stop paying you or not").

Not very realistic, IMHO. First, no ISP would put that in writing. The,
what happens if the ISP bellies up?

Michel.

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From: Robert Elz <[email-masked]>
Date: Fri, 28 Jun 2002 15:16:53 +0700

Date:        Thu, 27 Jun 2002 15:35:07 -0700
    From:        "Michel Py" <[email-masked]>
    Message-ID:  <[email-masked]>

  | but for the
  | two different methods that ipv6mh is working on, there is no relation
  | whatsoever between the network/fiber plant topology and the geographical
  | aggregation.

I am waiting to see how this is going to be achieved.  That is, all of
what you're promising in this message.   So far, from what I have seen,
I don't see how it can be done.   But maybe there's something out there
that I just don't understand yet.

  | True enough. However, you forgot two important things:
  | 
  | 1. If we make SLs with site IDs globally unique, there might be no
  | assignement (or the assignement might be automatically granted by the
  | addressing architecture, say a 37-bot hash of the MAC address, or
  | whatever). With the geographic scheme we are designing, there would
  | still be the need to go to a RIR and register a block, so we might still
  | decide that someone with a dial-up 28.8k modem does not qualify for a
  | portable, globally unique /48 block.

I certainly hope that isn't ever going to happen (with PI or PA
addresses).   The aim is a /48 for everyone (who requests one), right?

What this has to do with anything I said I'm not sure though.

  | 2. SLs do would not have a supporting protocol if used globally (how
  | could there be one, if they are not supposed to be used that way). The
  | way I see the geographical addresses is a support of the multihoming
  | protocol. And if there is a protocol, there can be safeties and policy
  | enforcement features built in.

Yes, there could be a protocol, with all kinds of things.  And it can be
turned off, or replaced, if it gets in the way.   Once RIP required that
there be only one subnet mask through a network ...

It isn't possible to enforce anything by relying upon protocols, we have to
depend upon agreements, and when appropriate "it is the only possible way".
The way we enforce aggregation now, isn't because there's some magic in
BGP that requires it, it is because we know of no other way to make routing
work.   As long as that remains true, we don't have to create protocols to
enforce aggregation in IPv6 - it will just naturally be enforced, because
no-one can figure out how to not enforce it (nb: it doesn't really matter if
a few stray /48's or even /128's "pollute" the global tables - remember the
aim is to keep routing working, not to enforce the rule just because it is
a rule).   If the assumption ("we know no way") ceases to be true, then
there's no reason at all that what we currently consider to be non-routable
addresses shouldn't appear in the routing tables.  Ie: as soon as it is
possible to put them there, any policy aimed at keeping them out no longer
has a purpose, and should be scrapped.

kre