[ale] V6 question

Michael H. Warfield mhw at WittsEnd.com
Sat Feb 5 16:49:09 EST 2011

On Sat, 2011-02-05 at 16:20 -0500, Mike Harrison wrote: 
> On Sat, 5 Feb 2011, Michael H. Warfield wrote:
> > NAT is dead in IPv6.  We will run public IP address.  But now we have to
> > call a spade a spade here.  Now it will be your router and your firewall

> They'll be handing out THAT much address space?

That much space is a lot of address space.  Enough to boggle the mind.

Each IPv6 /64 subnet is 64 bits of local address.  That's this number of
host addresses in each subnet:


One subnet has as many addresses as the entire IPv4 Internet squared.

Each /48 network contains 65,536 /64 subnets.  Each /56 network contains
256 /64 subnets.

> It's not uncommon to have hundreds or thousands of computers,
> with only a few "public" ip addresses.

There's currently enough allocated, advertised, and routed capacity in
the core gateways right now on IPv6 to hand each and every IPv4 address
a full /48 network.

That's a LOT of bloody address space out there handed out already.

On top of that, every IPv4 already has an IPv6 /48 network automatically
assigned to it and usable right now, whether your provider is providing
one or not.  They're called 6to4 addresses and they're formatted like

2002:{IPv4 Gateway}::/48

So the first 16 bits is "2002".  The next 32 bits is the public IPv4
address of your gateway.  That's your 48 bit network.  The next 16 bits
is your SLA or subnet number of which you have 65,536 subnets.  The
remaining 64 bits are for the EUI part of the address which will be
generated on your systems automatically in most cases and that's the
humongous number above.  They work, just turn them on.  But they don't
work over NAT.

> I think what I really learned today... is that I need to get edumacated 
> and/or possibly IPv6 certified.. and build a test network or three.

Check out Hurricane Electric aka tunnelbroker.net:


Lot's of good learn'n stuff up there.  If you want to work over NAT or
from dynamic addresses, you might want to learn what you need to learn
at HE but then get your address space from Freenet6 up at Gogo6:


You can get a free /48 network from Hurricane Electric or a free /56
network from Freenet6.  Freenet6 is a little easier to make work over
NAT or with dynamic IP addresses or if you want a little road warrior.
In fact, I have allocations from HE, OCCAID, and Freenet6 and prefer
OCCAID for my big networks and use the anonymous service from Freenet6
for road warrior roaming.

Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw at WittsEnd.com
   /\/\|=mhw=|\/\/          | (678) 463-0932 |  http://www.wittsend.com/mhw/
   NIC whois: MHW9          | An optimist believes we live in the best of all
 PGP Key: 0x674627FF        | possible worlds.  A pessimist is sure of it!
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