Subject: RIR ISP to end-user address allocation policy?

From: Pekka Savola <[email-masked]>
Date: Wed, 16 May 2001 14:56:54 +0300 (EEST)

Hello all,

In a very recent RIPE meeting 1st May, Mirjam Kühne and Randy Bush presented
the following on on IPv6 Address allocation policies:

http://www.ripe.net/ripe/meetings/archive/ripe-39/presentations/ipv6develop/

Among others, on slide 8, "ISP to Customer" there is:

---
* IAB/IESG recommended /48.
* Use a /128 where it is absolutely known that one and only one device is
required, e.g. dialup [<--!!!!!!!]
* Use a /64 when sure net will not be subnetted, e.g. a mobile phone given
802.11, bluetooth, etc.
---

I find this thinking, or at least the examples very flawed.

Anyone want to start implementing NATv6 for people whose ISP refuses to
give enough addresses to you can't (sub)network your home?

This is very much related to the ISP discussion here a week or two ago; if
ISP is allowed to assign /128, they probably will.

Issues here:

1) End-users connecting with dial-up, ADSL, or whatever
   * Should get _at least_ /64 (so no _serius_ need for NAT)
   * Should subnetworking be possible (perhaps yes)?
     ==> /48 would be optimal.

2) Apparently IAB/IESG proposal was not taken too seriously
   * With /48 to end-users, the address space would be exhausted;
     this would be only 16 (not really used in assignments) + IPv4 space.

     ==> _Did IAB/IESG propose how this should be solved?_

If this is a wrong list, please advise which would be better one.

-- 
Pekka Savola                 "Tell me of difficulties surmounted,
Netcore Oy                   not those you stumble over and fall"
Systems. Networks. Security.  -- Robert Jordan: A Crown of Swords

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---

From: Robert Elz <[email-masked]>
Date: Wed, 16 May 2001 20:51:53 +0700

Date:        Wed, 16 May 2001 14:56:54 +0300 (EEST)
    From:        Pekka Savola <[email-masked]>
    Message-ID:  <[email-masked]>

  | 2) Apparently IAB/IESG proposal was not taken too seriously
  |    * With /48 to end-users, the address space would be exhausted;
  |      this would be only 16 (not really used in assignments) + IPv4 space.

Huh?

With allocations at /48, the address space available to be allocated is
64K times as big as the entire IPv4 address space, and the allocation is
done in units of 1 regardless of how big the organisation is (at least
until it gets VERY huge indeed - bigger than needed to justify a /8 in IPv4
space - just for the organisation itself, we're not talking about clients
of ISPs here - then it can get 2...)

The actual multiple of IPv4 space is closer to 4 million (2^24) in practical
terms (based upon the approximation that the average size allocation in
IPv4 is about a /24 - with all the /24's allocated, and the /16's and similar
accounting for those allocations that are smaller than a /24).

The internet as it is is probably reaching (at least) 5% to 10% of the
planet - we only need a factor of 20 (but allow 100) to cover everything, and
then add in another factor of 1000 to rid us of all the NAT around.   That's
still just 100K out of the 24M available.   There's still room for expansion
to another 240 times that size...

It happens that the address plan is currently only allocating 1/256 of
the total space - which matches nicely with the amount that we're likely
to need sometime in the forseeable future.   Subtract off the 2/256 that
are in the "we won't use these" blocks, and the other 253/256 of the
total space is available for use, when we eventually find some way of
using it.

Allocating at /48 the address space is not about to be exhausted...  (and
anyone doing large numbers of allocations to very small users can allocate
/64's by default, and /48's to anyone who asks).

kre

---

From: Thomas Narten <[email-masked]>
Date: Wed, 16 May 2001 10:00:32 -0400

Hi Pekka.

Please read all of draft-iesg-ipv6-addressing-recommendations-00.txt
(or wait a day or to for -01) before jumping to conclusions. I believe
all of your issues are discussed there in detail.

Thomas

---

From: Pekka Savola <[email-masked]>
Date: Wed, 16 May 2001 17:43:10 +0300 (EEST)

> of ISPs here - then it can get 2...)

The first 2^16, and more, bits are not being used at the moment, but
that's not the point; they will be when needed.

The problem is that if dialups, adsl's etc. should be given /48, but the
organization is allocated one /48, how do you proceed?  Take for example
universities offering dialup, or companies doing it for the personnel; you
can't argue that these are always a part of the infrastructure, and should
be given /64.

From there, we go to a scenario where organization needs /48 for itself
and N * /48 (e.g. /35) for other connectivity.  However, please note that
e.g. 48-35 bits is not that much; organizations doing this would be
needing reallocations after reallocations of new addresses.

This might lead to an increased size of routing tables as you
might not be able to aggregate the prefixes properly.

> all of your issues are discussed there in detail.

Ah, thanks for the pointer.  This does clarify the recommendation a bit.

This states a lot more clearly that the default, unless otherwise stated,
should be /48.  The RIPE presentation, IMO, reverses this especially for
dial-ups.

The paper did not discuss the effect of allocating /48's and /35's now
(and probably /29..36 in the future) on the routing table sizes; was this
deemed a non-issue?

You can't fit _that_ many /48's in a /35 that are being allocated now.
That might cause aggregation fragmentation as more address space is being
asked from RIR's.

Perhaps I'm looking a bit too far in the future, imagining every
10th/100th dialup/DSL/etc. user might use IPv6 and want /48; current
/35 assignment policy would not be enough for that.

Who knows. :-)

---

From: lists <[email-masked]>
Date: Wed, 16 May 2001 10:07:16 -0700

> There is some debate between the optimists who argue that address space
> will be so large and plentiful that ISPs will just hand out /48's to each
> customer in accordance with IESG recommendations, and the pessimists who
> argue that ISPs will charge extra for anything they can, and will continue
> to charge much $$ for address space because that is the situation with
> IPv4.

Except that it's cheaper for the ISP to hand out /48's than to have billing
for 2 or more separate sized IP blocks -- as long as getting additional blocks
from the RIR is "easy". Stop thinking as if you're still caught in an economy
of scarcity...(grin)

> The odd conclusion of this argument is that we *need* NAT for IPv6, just
> to keep the ISPs in check.  If the IETF takes any measures to make NATv6
> infeasible, the IPv4 pricing paradigm will continue, regardless of how
> available address space becomes.  -Nathan

We also expect that NAT won't work for the next wave of killer apps as it
doesn't preserve end-to-end semantics. So your argument is half right on as
long as the usage of the internet is restricted to current applications (ie.
the web as an alternative to TV).

Adi

---

From: Nathan Lutchansky <[email-masked]>
Date: Wed, 16 May 2001 12:46:15 -0400 (EDT)

> ISP is allowed to assign /128, they probably will.

We need NATv6, in order to guarantee that ISPs will make address space
available.  Here's why.

In the end, the optimists will prevail, for the simple reason of market
competition.  Not ISPs competing with ISPs, however, but ISPs competing
with home-router vendors.  The plethora of $100 NAT boxes on the market is
ample proof that NAT can work just fine for the average consumer, and at
the same time is impossible for ISPs to restrict.

The NAT manufacturers want ISPs to continue to be stingy with their IP
addresses so they can continue to sell home/SOHO routers, and thus will
continue to advertise "Why pay for more than one IP?".  On the other hand,
the ISPs want to stop NAT use so they can accurately price their service
based on expected usage.  I would venture to guess that the ISPs will
eventually realize that they can't charge more for additional IP addresses
because they'll simply drive their customers behind NATs, so they'll
start utilitizing large address allocations as an extra service "perk".
After a time, this perk will become a standard feature of any ISP service.

-- 
+-------------------+---------------------+------------------------+
| Nathan Lutchansky | [email-masked] |  Lithium Technologies  |
+------------------------------------------------------------------+
|  I dread success.  To have succeeded is to have finished one's   |
|  business on earth...  I like a state of continual becoming,     |
|  with a goal in front and not behind. - George Bernard Shaw      |
+------------------------------------------------------------------+

---

From: Thomas Narten <[email-masked]>
Date: Wed, 16 May 2001 13:28:53 -0400

> Ah, thanks for the pointer.  This does clarify the recommendation a bit.

Good!!

> (and probably /29..36 in the future) on the routing table sizes; was this

draft-iesg-ipv6-addressing-recommendations-00.txt focusses pretty much
only on the argument for making /48 the normal allocation to end sites.

> That might cause aggregation fragmentation as more address space is being

This concern is being raised by others, and the registry communities
have recently begun discussing whether the /35 boundary should be
changed. See the "Next Steps" slide in the presentation you cited
earlier
(http://www.ripe.net/ripe/meetings/archive/ripe-39/presentations/ipv6develop/sld017.html),
for example.

Thomas

---

From: Nathan Lutchansky <[email-masked]>
Date: Wed, 16 May 2001 18:51:06 -0400 (EDT)

> from the RIR is "easy". Stop thinking as if you're still caught in an economy

Heh.  OK, so if the registries all agree that giving each customer a /48
whether they want it or not is a good use of address space, then I'm sure
that's the path the ISPs will take.  But as Dan Lanciani points out, ISPs
could easily filter out (2^48 - n) IP addresses in your /48, where n is
proportional to your monthly bill.  Regardless of how it is enforced, it
is a question of whether the restriction exists at all.

> the web as an alternative to TV).

I agree that NAT breaks a lot of things.  But I still maintain that the
software will always kludge around it, even if that takes a very ugly
kludge.  In particular, SIP has a lot of workarounds for NATs and other
firewalls, and I would expect that many of the future end-to-end killer
apps will be based on it.  -Nathan

---

From: Robert Elz <[email-masked]>
Date: Thu, 17 May 2001 13:39:52 +0700

Date:        Wed, 16 May 2001 17:43:10 +0300 (EEST)
    From:        Pekka Savola <[email-masked]>
    Message-ID:  <[email-masked]>

  | The problem is that if dialups, adsl's etc. should be given /48, but the
  | organization is allocated one /48, how do you proceed?  Take for example
  | universities offering dialup, or companies doing it for the personnel;

This depends upon the environment.   In some cases there is essentially an
ISP in existence, which should have a /35 (or whatever that turns out to be)
from which to hand out pieces, one of which would be a /48 for itself, and
the rest for its "customers".

In most cases however (such as the university that employs me), the subnets
handed out to dial ins are just a part of our network (they are for v4, and
will remain so for v6), and are all managed together - dial in users get
as much address space as they need (and independent of the technology that
they use to connect).   I have a subnet for home from that space which is
just as much as I need.   Because of the relationship that exists all this
is pretty easy to manage - that is, that the subnet happens to exist in
my house doesn't make it any difficult than a subnet that exists in some
university owned building.

Students we tend to push towards using a commercial ISP though in general,
it makes lots of sense all around.

But note that I wasn't advocating a /48 for every dial up user - I think that
much smaller allocations will work fine for almost all (down to /64)
low end connections (clearly a /64 will work for everyone with only a
single subnet at the other end, provided the routing is managed correctly).
What is important is to make available the address space that people
actually need - and not to be too bothered about their rationale for their
needs (up to as big as /48 allocations anyway) - if they think they need it,
allocate it, just default to smaller for people who have no idea.
(A question on the ISP form might be "Do you need more than a hundred million
addresses?").

  | This might lead to an increased size of routing tables as you
  | might not be able to aggregate the prefixes properly.

The original model had the ISP returning their /35 (after an overlap
period) when they get given the /32 (or /33 or /29 or whatever it is)
when they have outgrown it, precisely to avoid this problem.  Of course,
this means that all of their customers need to renumber.   This kind
of thing was the prime motivation for making renumbering practically
possible, and comparatively easy - not the "I want to change ISPs and
don't want to have to renumber" which is of rather lower importance
(anything caused by a voluntary action is much easier to deal with than
something you have to do without choice and without any obvious benefits).

kre