NAT usage at large companies (was: Re: [e2e] Number of persis tent connections per HTTP server?)

Johnson, Edward edward.johnson at
Thu Oct 17 06:53:23 PDT 2002

I work for a company with approximately 20000 users.  Our enterprise network
is addressed in compliance with RFC1918 private addressing therefore all
traffic exiting the enterprise network to the Internet must be NATed and
uses one address.  In our case NATing is performed both for security and
address conservation.  I believe that this solution is in wide use among


Edward Johnson
WAN Engineer
Capital One
phone	804-934-7237
page	888-825-2751
cell	804-307-7118
text page  (8252751)

-----Original Message-----
From: Bengt Gördén [mailto:bengan at]
Sent: Wednesday, October 16, 2002 4:55 PM
To: end2end-interest at
Subject: Re: NAT usage at large companies (was: Re: [e2e] Number of
persistent connections per HTTP server?)

On Wed, Oct 16, 2002 at 11:12:56AM -0700, John Heidemann wrote:
> On Mon, 14 Oct 2002 22:42:33 PDT, Vadim Antonov wrote: 
> >On Mon, 14 Oct 2002, Joe Touch wrote:
> >> Since the NAT likely shares the majority of the path that determines
> >> and bandwidth, it won't hurt sharing.
> >
> >Very often, this is not the case.  What you have in a typical
> >is single NAT/firewall, and a VPN behind it.  Quite often parts of that
> >VPN are on different continents :)
> Can folks offer some more details about how prevalent this kind of
> NAT deployment is?

I can only speak for the network that I'm part of the NOC for, and that
is SUNET (AS1653). We have about 30 Universities connected to
SUNET. University's are connected with 2.4Gbit/s access. Of them I know
2 that actually have off-the-shelf-firewall with NAT involved. I think
actually they're 3 but I don't have that confirmed. Several of the
others put the students appartments behind NAT.

The problem we see is that we try to motivate them to apply
for IP-addresses (we do have a few ipv4 left over :-) but they still
want to NAT because of the security that it brings.

> My assumption was that NAT is primarily used by homes/small
> organizations that are geographically co-located.

In our case the University's are spread out over the country and maybe
they are small (it depends with what we compare) but they have about
5000-20000 users (students and staff) each.

> etc.  (Insert your own more inflamatory statements about NAT here.)

It breaks end-to-end. :-)

- Bengan -----------------------------------------------------------
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