What's the current state of major access networks in North America ipv6 delivery status?

Mark Andrews marka at isc.org
Wed Jan 26 18:43:31 CST 2011

In message <BACEA722-744B-4773-89EF-03FBB933E1E4 at delong.com>, Owen DeLong write
> On Jan 26, 2011, at 1:52 PM, Charles N Wyble wrote:
> > Hash: SHA1
> >=20
> >=20
> > Is anyone tracking the major consumer/business class access networks
> > delivery of ipv6 in North America?
> >=20
> > I'm on ATT DSL. It looks like they want to use 6rd? I've only briefly
> > looked into 6rd. Is this a dead end path/giant hack?
> >=20
> > =
> https://sites.google.com/site/ipv6implementors/2010/agenda/05_Chase_Google=
> conf-BroadbandtransitiontoIPv6using6rd.pdf?attredirects=3D0
> >=20
> It's a fairly ugly way to deliver IPv6, but, as transition technologies
> go, it's the least dead-end of the options.
> It at least provides essentially native dual stack environment. The
> only difference is that your IPv6 access is via a tunnel. You'll =
> probably
> be limited to a /56 or less over 6rd, unfortunately, but, because of the
> awful way 6rd consumes addresses, handing out /48s would be
> utterly impractical. Free.fr stuck their customers with /60s, which is
> hopefully a very temporary situation.

This comes from using a single 6rd prefix for all the clients.

Those saying this is the way to do this really havn't thought about
what they are going to have to do once they can't get enough IPv4
addresses to give a public one to each customer that needs a IPv4
addresses and also needs 6rd.  The "simple" solution of a signgle
prefix doesn't work.

6rd doesn't have to consume space badly and it shouldn't consume
space badly if done right.

DHCP servers don't hand out the same router to each client.  They
hand out the same router to all clients on the same subnet.  ISP's
are capable of configuring their DHCP servers to do that.  Configuring
them to hand out a 6rd prefix on a per subnet basis is no harder.

Just ask for a /48 for each IPv4 address you intend to support 6rd
on.  For each block IPv4 block you get from RIR you specify a
matching 6rd prefix.  This prefix is stable for the life of the
IPv4 block's allocation.  When you get a new IPv4 block you add the
6rd prefix to the configuration system.

If you are using RFC 1918 addresses to connect to your customers
and NATing that you request enough /48's to cover the amout of RFC
1918 space you are using.

If you are re-using space in multiple places then 6rd becomes a
little more complicated as the prefixes need to differ for each
re-uses.  Note the naive single 6rd prefix doesn't work in this
situation so ISPs doing this will need do something more complicated.

Also give that address space will almost certainly need to be re-used
while 6rd is also in use I fail to see the objection to doing it
sensibly from the get go.

Down the track I can see 6rd prefixes being allocated on request
being just one more thing that the consumer can request via a web
form.  This will allow the ISP to recover the space being used by

> >=20
> > I spoke with impulse.net last year, which appears to serve large
> > portions of the AT&T cable plant in Southern California. They were
> > willing to offer native ipv6. Not sure how (one /64, a /48) etc.
> >=20
> You should definitely push your providers to give you a /48 if
> possible. If /56 or worse /60 or worst of all, /64 become widespread
> trends, it may significantly impact, delay, or even prevent innovations
> in the end-user networking/consumer electronics markets.
> Owen
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org

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