Comcast Activates First Users With IPv6 Native Dual Stack Over DOCSIS

Bernd Walter ticso at
Wed Feb 2 14:23:17 CET 2011

On Wed, Feb 02, 2011 at 11:03:05PM +1030, Mark Smith wrote:
> On Wed, 2 Feb 2011 07:05:58 -0500
> Jared Mauch <jared at> wrote:
> > 
> > On Feb 2, 2011, at 3:41 AM, Mark Smith wrote:
> > 
> > > On Mon, 31 Jan 2011 16:50:09 -0500
> > > John Jason Brzozowski <jjmb at> wrote:
> > > 
> > >> FYI
> > >> 
> > >><>
> > >> ive-dual-stack-over-docsis.html<>
> > >> 
> > > 
> > > Why a single /64? You certainly won't be only getting just a /32, and
> > > I'm sure you've got way less than 4 billion customers. A /60 would have
> > > been a conservative option if you wanted to dip your toe in the water,
> > > yet still would allowing people to use subnets in their home if they
> > > wanted to perform some of their own experiments - your trial
> > > participants are more likely to have a few routers in their home that
> > > they may want to use to experiment with IPv6 and IPv6 routing.
> > 
> > This is comcasts experiment, not the end-user.  If the end-user wants to experiment, they can go find access via some other provider (eg: tunnelbroker, etc).

>From my point of view there are a view points to worry with mass
providers deployment.
I'm not talking about services for business customers - they always get
what they want if they care.
The typical home user however just want's to surf through the internet
and doesn't want to care about technical things.
This results in a single network, don't care about dynamic IP or NAT.
TV, WLAN, fridge, VOIP-phone, light-switches, ... are all connected
to the same LAN.
NAT and dynamic IPs are challenging some of the devices as we all know.
Today a standard user get's a single dynamic IPv4 address and has a
flat intra-LAN connected via NAT.
When the user wants to have a different network for his WLAN or even
light switches then it's no problem because intra addresses are
available more than a home user can ever use and those intra addresses
never change - they get this with a standard cheap IPv4 access.
Now there is IPv6 and deployment of single /64 - some even put their
strategy into things like 6RD, which means that this single /64 is
even as dynamic as their IPv4 address.
Now IPv4 devices can have plenty of networks with fixed intra addresses
and with IPv6 all of them are required to be within the same single LAN
and undergo regular address changes - this really goes into the wrong
Even home users can't really live with a single LAN and want static
addresses for their internal DNS or whatever.
Should they use NAT and intra-addresses for IPv6 as well?
Put their VOIP phone behind NAT or proxy to not have them share the
same network as their IPTV equipment?
Maybe the dynamic /64 is Ok for masses, but I'm really scared if
mass providers won't offer alternatives, so that consulters for home
users can't setup a reasonable network without adding the old crappy
workarounds like NAT, dynDNS, ... we all hate today.
It's not typical today, but home users want to access their frigde
from work before they drive home to verify what they need to fetch in
the supermarket.
They want to verify if the light is really off with their smartphones
when they already left home.
All of this requires devices to be reachable from everywhere and this
works best with fixed addresses without NAT although we have established
It's Ok to live with those restrictions under IPv4 because there is no
other option, but what is the fucking reason to do the same with IPv6?
I assume a conservative fixed /60 for 16 LANs would satisfy almost every
home user, but a single /64 won't.
It is counterproductive to speak about 2^64 addresses delivered with a
single /64 when we all know that all of the device classes with such a
density require LAN isolations, which is simply not possible with such
an allocation.
It's Ok if they need to register to such extended service, but in my
opinion this option must be available for every customer.
If it is all just to get them surfing IPv6 sites, why bother with IPv6
to clients at all if they could also run IPv4 and use ISPs proxies to
access IPv6 sites?

B.Walter <bernd at>
Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.

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