Subject: Re: Sequentially assigned IP addresses--why not?

From: "Steven M. Bellovin" <[email-masked]>
Date: Thu, 10 Aug 2000 16:40:44 -0400

In message <[email-masked]>, "Cor
zine, Gordie" writes:
>Seriously,
>
>As was pointed out recently, IPV6 will croak much sooner than it needs to
>for the simple reason that we structure routing intelligence into the
>address assignment.
>
>Wouldn't it be better by far, to assign new addresses from 000...1, and map
>to routing information however we may code it?  The memory and processor
>steps required would be trivial compared to the agony of running out of
>space again.

The problem is that we (as a profession) don't know how to do that.  We 
have to make routing scale, and that demands aggregation, which 
in turn demands structured addresses.

Look at it this way.  We have about 75K routes in the "default-free 
zone" now.  If we just assigned addresses sequentially, we'd need a 
route for every endpoint.  There are what, 100,000,000 nodes today, and more 
tomorrow?  We can't handle 3 orders of magnitude increase in the size 
of that table, let alone what it will be in a few years.

There are lots of other practical issues, but that's the big one.

		--Steve Bellovin

---

From: "Anthony Atkielski" <[email-masked]>
Date: Fri, 11 Aug 2000 02:40:32 +0200

> The problem is that we (as a profession) don't know
> how to do that.  We have to make routing scale, and
> that demands aggregation, which in turn demands
> structured addresses.

The telephone company figured out how to avoid problems decades ago.  Why
the computer industry has to rediscover things the hard way mystifies me.

---

From: Vijay Gill <[email-masked]>
Date: Thu, 10 Aug 2000 23:43:05 -0400

> the computer industry has to rediscover things the hard way mystifies me.

Oh god, not this argument again.

This is the circuit vs connectionless debate.  I am sure if you do a
search on Kleinrock and Mills in open literature, you will find all sorts
of reasonings behind why this divide exists.

To grossly oversimplify things, the phone systems do a relatively slow
setup and once it is set up, let it stay till it is done and then tear it
down.  There isn't a phone company that does setups and teardowns (if I
may stretch the term) at a rate that can match the connections initiated
and torn down involving tcp/ip for http alone that pass through a core
router in any promising local ISP.

See ATM to the desktop.

/vijay

---

From: Brian E Carpenter <[email-masked]>
Date: Fri, 11 Aug 2000 09:38:52 -0500

> the computer industry has to rediscover things the hard way mystifies me.

The telephone company has milliseconds to seconds to resolve an address
into a route. The Internet has microseconds to nanoseconds to do so.

---

From: John Day <[email-masked]>
Date: Fri, 11 Aug 2000 11:49:45 -0400

>router in any promising local ISP.

Actually it has less to do with the connectionless/connection debate 
and more to do with what they are naming.  What the phone companies 
did (and the Internet as yet to do), was precisely what John Shoch 
outlined in his paper over 20 years ago and that Saltzer expanded on 
not quite 10 years later.  They made the location independent 
"addresses" application names and kept the location dependent names, 
i.e the addresses on which they do their routing.  These network 
addresses are the same as the ones they have always been using but 
they are only internal.  It is just that they used a similar syntax 
for both to give people the impression they were actually doing 
something else.  But the syntax of the names has nothing to do with 
their semantics.

Now, it is the case that most communication with applications both in 
the phone system and on the Internet is connection based so this 
mapping does not have to be done too often.  So there is a connection 
(no pun intended) but it is distinctly secondary.  However, it 
remains that it is applications that should have location independent 
names and network addresses that should have location dependent names.

Take care,
John

---

From: Lloyd Wood <[email-masked]>
Date: Fri, 11 Aug 2000 18:41:23 +0100 (BST)

On Fri, 11 Aug 2000, John Day wrote:

> i.e the addresses on which they do their routing. 

In other words, they introduced a level of indirection. You can fix
many design decisions with a level of indirection.

Phone numbers have moved from being direct as originally implemented
to being a level of indirection, thanks to a lot of behind-the-scenes
mucking about. The Internet introduced DNS to gain that same level of
indirection. Phone numbers are now portable; DNS names are portable.

L.

<[email-masked]>PGP<http://www.ee.surrey.ac.uk/Personal/L.Wood/>

---

From: "Anthony Atkielski" <[email-masked]>
Date: Fri, 11 Aug 2000 20:57:32 +0200

> The telephone company has milliseconds to seconds
> to resolve an address into a route. The Internet
> has microseconds to nanoseconds to do so.

Build faster hardware.

---

From: "Salavat R. Magazov" <[email-masked]>
Date: Fri, 11 Aug 2000 20:27:45 +0100

Hello

What is the difference between plain address (I mean house address like 47
Ulcombe gardens, Canterbury, Kent, United Kingdom) and IP address. The
former is scalable to whatever size one may want and the router for plain
address (i.e. post office in USA, for example) does not have to know about
47, Ulcombe and so on it only must know what direction UK is located. Why
not to take this analogy and use it in the Internet. The difference is not
very big, since plain mail system is connectionless.

Regards
Salavat

---

From: "Matt Crawford" <[email-masked]>
Date: Fri, 11 Aug 2000 14:56:47 -0500

> indirection. Phone numbers are now portable; DNS names are portable.

I don't agree with that.  Host names, and a means for translating
them to addresses, existed before DNS.  Introduction of hierarchical
naming and DNS let the maintenance of this translation mechanism be
decentralized.

Hm, wasn't this thread started by a suggestion that so-called
addresses be assigned under centralized control?

---

From: Geoff Huston <[email-masked]>
Date: Sat, 12 Aug 2000 07:11:49 +1000

At 04:40 PM 8/10/00 -0400, Steven M. Bellovin wrote:
>zone" now.

No - that was March 2000 - now we have about 87,000 (www.telstra.net/ops/bgp)

>   If we just assigned addresses sequentially, we'd need a

There are a number of scenarios which will make the routing system
crash and burn - this is one of them. On the other hand even doing
nothing will be a problem - we appear to have resumed exponential
growth of the routing system again, presumably as multi-homing at
the edges starts to be more and more common.

   Geoff Huston

---

From: Brian E Carpenter <[email-masked]>
Date: Fri, 11 Aug 2000 17:14:13 -0500

Try reading one of the books on Internet routing, there are
several good ones.

   Brian

---

From: Bill Manning <[email-masked]>
Date: Fri, 11 Aug 2000 18:02:30 -0700 (PDT)

% On the other hand even doing
% nothing will be a problem - we appear to have resumed exponential
% growth of the routing system again, presumably as multi-homing at
% the edges starts to be more and more common.
% 
%    Geoff Huston

As predicted back in the cidr development days.  people multihome for
a number of reasons, not the least of which is the avoidance of a single
point of failure. Turning the routing system into the functional equivalent
of monoply pyramid will bring down the rath of the regulators, even if there
is "nothing" we can do.

-- 
--bill

---

From: "Donald E. Eastlake 3rd" <[email-masked]>
Date: Sat, 12 Aug 2000 00:41:43 -0400

If IPv4 multihoming is leading to exponential growth of the routing
tables, maybe that's what will kill IPv4 and push people to IPv6.  My
understanding is that in IPv6 things are better because, to some
extent, you can multihome by having multiple addresses assigned by
your different providers.  Of course that can add a new exponentiality
based on your depth in the provider/sub-provder tree....

Donald

From:  Geoff Huston <[email-masked]>
Message-Id:  <[email-masked]>
Date:  Sat, 12 Aug 2000 07:11:49 +1000
To:  "Steven M. Bellovin" <[email-masked]>
Cc:  [email-masked]
In-Reply-To:  <[email-masked]>

>>...

---

From: Lloyd Wood <[email-masked]>
Date: Sat, 12 Aug 2000 15:36:47 +0100 (BST)

On Fri, 11 Aug 2000, Matt Crawford wrote:

> them to addresses, existed before DNS.

Yes, but downloading hosts.txt from a single source is nowhere near
the same level of behind-the-scenes mucking about of DNS, and can be
thought of as roughly equivalent to having one phone company on the
planet - and one that prints letters on its handsets' keys, at that.

L.

> Introduction of hierarchical