Re: [v6ops] IPv4 trajectory

[Lee Howard <[e-mail]>]

On 3/31/15, 1:35 AM, "Fred Baker (fred)" <[e-mail]> wrote:

>In the course of the Google Doc ³towards IPv4 as a service² discussion,
>Brian Carpenter wrote
>
>> Scope question: do we need to distinguish edge networks from Tier 3
>>provider networks? Are we making the assumption that transit and core
>>carriers remain dual-stack? Listing LISP suggests that we might not be
>>making that assumption exactly.
>
>Let me give you my thought process. Happy to be told I am wrong.
>
>As I read RFC 4213, the transition process was envisioned as taking three
>steps:
>
>1) IPv4-only
>2) IPv4+IPv6 Dual Stack
>3) IPv6-only
>
>Had the transition started five or ten years ago, that might have been
>reasonable. Where things stand, though, I don¹t think it is. From my
>perspective, the process over some amount of time into the future (amount
>of time is anybody¹s guess) will take six steps:
>
>1) IPv4-only network
>2) IPv4 with bits of IPv6 here and there, in some combination of overlay
>and native
>3) IPv4+IPv6 (native) dual stack network
>4) IPv6+IPv4 non-native, translated or overlay (e.g., as a service)
>5) IPv6 with little bits of IPv4 here and there; your printer might be an
>example
>6) IPv6-only

Exactly. Note that networks do not move monotonically. That is, for an
eyeball or mobile network, their work may be complete when only 30% of
users have IPv6, and they have to wait for IPv6-incapable user equipment
to age out. That could be step 2, or step 3, or even a messy combination
in which:
a. Some users have native IPv4-only
b. Some users have native dual-stack
c. Some users have native IPv6 with IPv4 and an overlay
d. In cases where 6rd (mostly) was used, some users have native IPv4, with
IPv6 as an overlay

Those may all exist in a single network.

>
>In steps 1 and 2, it is an IPv4 network, possibly with some toys in it
>playing IPv6. We might have toys playing AppleTalk and DECNet too. IPv4
>is the workhorse, and toys is toys.
>
>In step 3, every host in the network has an IPv4 address and an IPv6
>address, or constructively could have if it wants one, and every router
>is carrying IPv4 routing as well as IPv6 routing. It¹s likely
>multiplexing IPv4 addresses, and IPv4 is increasingly broken. But the big
>question is what applications and providers support IPv6; as long as a
>big one (Skype?) is not making the transition, people have a business
>reason to keep IPv4 going. As applications become dual stack, traffic
>levels approach a 50/50 distribution, barring some specific reason they
>would be forced to IPv4 or IPv6.

Fewer and fewer networks will be doing step 3. If they aren't close to
rolling out, they simply won't have the IPv4 address space to do native
dual-stack. I think we will start seeing networks skipping steps.  But
again, these will co-exist; existing customers or installations will
probably remain IPv4-only, with new devices being enabled with IPv6, with
IPv4 as a service. The rest will be transition by attrition.

>...
>
>
>Listing LISP... to me, LISP is yet another encapsulation, a tunnel
>broker, and one that is particularly complex. It can carry IPv6 across an
>IPv4 network or IPv4 over an IPv6 network. Someone suggested it should be
>on the list, and it¹s on the list. One thing I actually expect is that
>the list of technologies we might invite deployment reports regarding is
>longer than the list of technologies people actually use. We might learn
>something from that.

We would also learn something if we get no deployment reports for certain
technologies.



>
>Is anyone¹s head exploding yet?

I was wondering what that sound was.

Lee