Subject: RE: [Ieprep] Understanding Congestion

From: "King, Kimberly S." <[email-masked]>
Date: Thu, 26 Dec 2002 08:20:50 -0500

Bill said:
>NATs are a hack which equipment vendors created 
>in response
>to artificial scarcity of IP addresses which marketing idiots 
>in some ISPs
>dreamed up as a way of getting back towards profitability after they
>priced transit too low ...

For an alternate perspective on addresses,

"Everyone who wants one is not able to get one
Example: People's Republic of China
1.3 Billion people
Order of magnitude growth in Internet usage year over year
~9M addresses in 1999
~16M addresses in 2001
Do we simply assume that anyone who has not already asked never will? 
Africa, South America, India, Arab world..."
http://www.isoc-au.org.au/Events/IPv6Direction.ppt

Kimberly
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From: Bill Woodcock <[email-masked]>
Date: Thu, 26 Dec 2002 08:12:31 -0800 (PST)

> "Everyone who wants one is not able to get one

Yes, but the question was why NAT exists.  Nobody was thinking of China
when NAT was created, it's just a gross hack.  IPv6 is the solution to the
"not enough IP addresses" problem.  NAT doesn't create any additional IP
addresses, so it can't solve China's problem.

                                -Bill

---

From: Dave Crocker <[email-masked]>
Date: Sat, 28 Dec 2002 12:43:02 -0800

Folks,

Bill> Yes, but the question was why NAT exists.  Nobody was thinking of China
Bill> when NAT was created, it's just a gross hack.  IPv6 is the solution to the
Bill> "not enough IP addresses" problem.  NAT doesn't create any additional IP
Bill> addresses, so it can't solve China's problem.

I do not like NAT, either, but we need to be careful about dismissing it
simply as a hack. It responded to two, real-world issues:

1.  NAT environments has been more convenient for small networks than was
(is?) possible without NAT.  That's not an address space issue, but a
network (and host) administration issue.

2.  In effect, NAT does for a network what common networking software does
for a host.  That is, it provides an integrated point of lower-level
addressing for a collection of processes (machines.)  In effect, one can
call this a kind of addressing data compression.  Data compression is a good
way to increase virtual throughput, so in fact one can argue that NAT does,
in fact, achieve the same address scaling effect as adding new address
space.

d/
-- 
 Dave <mailto:[email-masked]>
 Brandenburg InternetWorking <http://www.brandenburg.com>
 t +1.408.246.8253; f +1.408.850.1850

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From: Bill Woodcock <[email-masked]>
Date: Sat, 28 Dec 2002 16:59:57 -0800 (PST)

> network (and host) administration issue.

NAT mitigates the problem of renumbering as well as the problem of
artificial scarcity, but at the cost of many many other problems.  That's
hardly beneficial, by any measure.

                                -Bill

---

From: RJ Atkinson <[email-masked]>
Date: Mon, 30 Dec 2002 10:53:13 -0500

On Thursday, Dec 26, 2002, at 08:20 America/Montreal, King, Kimberly S. 
> http://www.isoc-au.org.au/Events/IPv6Direction.ppt

The above analysis is popular with IPv6 advocates, but is a deeply 
flawed analysis.

If one actually talks with APNIC (or with large Chinese customers) and 
asks
probing questions, what one finds out is that even China is able to get 
all
the IPv4 address space that it needs now and for many years into the 
future.

The popular claim that China "needs 70 Class-A networks today" also 
turns
out to be boldly wrong when one does careful analysis or talks with the
informed folks inside the Chinese administration.  The allegation that
"China needs 70 Class-A networks" has been popularised in China by a 
large
equipment vendor who has the commercial motivation of selling 
IPv6-capable
equipment.  It turns out to not be true today.  It might be true at 
some future point,
of course, since IP address space (either version) is finite.  And 
among the
many flaws in the above analysis is that address reclamation of IPv4 
address
*IS* happening (e.g. 36.0/8 used to belong to Stanford University and
has since been returned to IANA for allocation to registries when 
needed).

Ran
[email-masked]

PS:	I've coded up more IPv6 implementations than anyone else on the 
planet,
including cisco's and the NRL implementation for BSD (which was the 
world's first).
Extreme has an IPv6 implementation and has had such for a while now.

PPS:	These views are my own and are in no way reflective of any position
of my employer.  Further, my comments in any IETF context are always 
made
as my own view, whether or not they agree with whatever my employer 
might
think.

---

From: RJ Atkinson <[email-masked]>
Date: Mon, 30 Dec 2002 10:56:16 -0500

On Saturday, Dec 28, 2002, at 15:43 America/Montreal, Dave Crocker 
> in fact, achieve the same address scaling effect as adding new address

The above is on target and important for everyone here to understand.

A third bullet (albeit perhaps a bit cynical) is that:

3.  NAT demand was significantly increased by misleading marketing from
     equipment vendors trying to generate demand for equipment that had
     NAT capability.  Once the equipment was in hand, users creatively 
found
     many novel ways to deploy the NAT capability.

---

From: Rex Buddenberg <[email-masked]>
Date: 30 Dec 2002 07:55:40 -0800

Kimberly,

Bill is basically right, if a bit low on the PH scale for my taste. NAT
boxes were a kluge to allow a unit (community college in my experience)
to shift ISPs (which required a wholesale change in IP addresses)
without visiting every office. 
 
The symptom of Internet scale problems were the _perceived_ exhaustion
of IP addresses (greatly exacerbated by the tendency of each requester
to ask for a Class B address regardless of real needs).  

The IPng exercises showed us that something like <1% of the addresses
assigned were actually being used.  Enter things like CIDR and DHCP
which enormously improved the efficiency -- and postponed the need for a
larger address space for at least a decade.  (NAT is known as IP
Masquerade in the Linux world for those wishing to track down how to use
it at home).

What was really hurting in the Internet a decade ago was the inefficient
assignment of routes. Each address block  showed up in a lookup table in
the routers' RAM.  This was both devouring RAM at increasing rates and
causing lookup inefficiencies -- something routers do for _every_
datagram through the box.  Classless InterDomain Routing (CIDR) pretty
much repaired this problem through route aggregation.  Of the facets of
this note, CIDR is the one tool that made routers work better, hence has
an impact on congestion.  

Your comment (below) sounds more down DHCP's alley than NAT -- not all
of those addresses will be in use at any point in time. DHCP allows you
to scavenge and reuse.  While routers like addresses in tidy blocks,
DHCP is essentially the sysadmin's sanity saver. (Note that the phone
company has been doing an analog for years: they tend to provision one
port on the switch for every 10 lines in the local loop on the
assumption that no more than 10% of the phones will be in use at a
single time).  

Eventually, IPv6 will indeed be necessary.  My guess is that the
cellphone and cable modem folks will hit the wall first.  Most OSs
(including those in routers) know how to handle it today but it's not
widely used yet.  

Accounting.  Counting IP address demand by counting human noses is a
crude way to do business.  In the two-decade-old timeshare days the
number of hosts was much less than the number of users so that method
was not realistic then.  Today, it's equally hokey because we're
increasingly assigning IP addresses to wholly inanimate objects like
unmanned sensors.  So the number of IP addresses may very well exceed
the number of warm human bodies.  I'd expect this to be the case in
spades in the emergency services world where fire, chemical, bio and a
host of other sensors will be wholly unmanned but have e-mail user
agents in them to send you mail when they detect what they're designed
for ... so they need addresses.  (And I wouldn't want to think about
managing that with a bunch of NAT boxes in the way;)