Why do we still need IPv4 when we are migrating to IPv6...

Tore Anderson tore at fud.no
Fri Feb 13 13:38:33 CET 2015

* Anfinsen, Ragnar

> On 12.02.15, 22.53, "Tore Anderson" <tore at fud.no> wrote:
> >There's a non-zero amount of end customers who *do* care about IPv6.
> >After all, you do have a opt-in service which several thousand of
> >your customers did actually opt in to - so it would seem to me that
> >several thousands of your own customers disagree with your statement
> >above.
> >
> >In the same way, you in all likelihood have a non-zero amount of end
> >customers who do care about having a public IPv4 address all to
> >themselves. If you did make this an opt-in feature, I'm sure you'd
> >have many thousands of users opting in to that, too.
> Compared to the amount of customers, only 1,6% of all our customer
> having the opt-in option have done so for IPv6. Back in the days when
> we where doing CGN (yes we have done it for more than 10 years),
> around 25% of our customers chose to opt-in for a public IPv4
> address. The main reason for this was that CGN did disrupt their
> service. Typical examples where OTT SIP services that did not support
> STUN, customers who wanted to have their own server at home, gamers
> and more.

Note that with MAP (maybe also lw4o6, but I'm less familiar with it)
home servers will work. This is because the customer actually does get
a public IPv4 address routed to his CPE - the additional restriction is
that he is limited as to which source ports he can use. So he can't
expect to be able to set up his SSH server on port 22/tcp, but he will
be able to set it up on some other port which might well be sufficient
for his use case.

Same thing goes for gamers, there the inbound ports are typically
dynamically assigned with UPnP or something like that, so the CPE is in
a position to simply assign a port from its assigned range for inbound
traffic. So for gamers, MAP ought to be pretty much equivalent to
regular public IPv4 with NAT44 in HGW.

Anyway, if 25% of your customers have a problem with traditional
stateful CGN, then you can expect that less than 25% would have a
problem with MAP. Not only because more application protocols work, but
also because the mandatory native IPv6 will help avoid problems by
sidestepping the MAP system and the CPE's NAT44 completely.

> So I disagree with your statements. 25% of the customer base don't
> care about addressing, but they do care about connectivity, and as
> long as there are no perceived differences between IPv4 and IPv6. The
> 1,6% who have chosen to opt-in for IPv6 are the geeks and the curious
> people.

I'm not sure how you can disagree with my statements, since you confirm
them to be true:

1) A non-zero amount of your customers (1.6%) care about IPv6
2) A non-zero amount of your customers (25%) care about public IPv4
3) The majority of your customers (73.4-75%) do not care about neither
   IPv6 nor public IPv4

Right? Group #3 is where you have the largest potential for starting to
break free of IPv4...

> >But if you flip it around, there's a non-zero amount of end customers
> >who do not care about neither having an exclusive public IPv4 address
> >nor about having IPv6. If I were to venture a guess, that group would
> >constitute the majority of your customers. Reclaiming those addresses
> >would likely allow you to postpone your next IPv4 purchase quite a
> >while, so I'd give that approach serious consideration if I were you.
> With reference to my statement above, reclaiming is not something you
> can do without the customer having a choice, and who would like to
> get their services degraded?

I've never suggested that you should not give the customer a choice.
Quite the opposite, I think you *should* give them a choice to have a
public IPv4 address. That way, you can in good conscience keep your
«premium» label - just like you do with your by-choice IPv6 offering.

How to introduce it to existing customers, you might ask? Maybe just
ask them? Send an SMS saying 20% off your next bill if you give up your
IPv4 address (and enable IPv6?), pointing out it's not binding and can
be re-enabled at any time. Or introduce a new invoice item for IPv4
with a symbolic charge, reducing the base fee accordingly so the total
stays the same. Inform them that the IPv4 charge can go away if they
disable the public IPv4 option in the customer portal.

If ~10k customers take the bait, hey presto, you have reclaimed enough
addresses to grow by ~40k new subscribers. I can guarantee you that at
least 1 customer would opt out of public IPv4 btw. ;-)

> Just to be clear. I am not speaking against IPv6, quite the contrary,
> as you know I have been a pro IPv6 tech for a long time, but I still
> have my management team to deal with. And we are not saying "no
> IPv6", we have rather moved on to "no IPv4?". I think it is to early,
> and CGN will degrade our service for 25% of our customers, which is a
> bit to high as of today.

I think you must have misunderstood me completely.

I am *not* suggesting that you deploy MAP/CGN for those 25% of your
customers who would consider this as a service degradation (group #2).
Quite the opposite, those 25% are precisely the ones who should *not*
be placed behind MAP/CGN.

What I *do* suggest that you look into, is MAP/CGN for the 75% of your
customers who would *not* consider it a service degradation (group #3).
Those customers are the low-hanging fruits, and considering that
there's three times as much of them as there is high-hanging fruit
(group #2) so it's the only logical place to start IMHO.

But if that's out of the question too, I honestly see no other option
for you than to keep on buying second-hand IPv4 addresses to fuel your
growth for the forseeable future.


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