[RRG] Consensus? IPv4 scaling problem must be solved directly, not by relying on migration to IPv6

[Robin Whittle <rw@firstpr.com.au>]

I think the map-encap schemes (LISP, APT, Ivip and TRRP) were all
designed on the assumption that we must solve the routing scaling
problem in IPv4 and the one which would develop if and when IPv6 is
widely adopted.

Here is why I think we can't just solve the future IPv6 problem and
rely on the IPv4 problem being solved - or becoming no longer a
concern - due to most end-users no longer needing IPv4 space.  This
could only be the case after "all" end users have IPv6 addresses and
suitable operating systems and applications.

IPv6 has been available in operating systems for at least 10 years,
but in terms of adoption, it has been a spectacular failure.  This
long-standing pattern of lack of interest among end-users would have
to be dramatically changed if IPv6 was to make the IPv4 routing
scaling problem no longer a concern.

In order for IPv6 adoption to play a significant role in the
reduction of the IPv4 routing scaling problem, several things would
need to be true:

1 - A significant number of new or existing end users (and their
    ISPs) would need to run their Internet services using only
    IPv6 addresses.


2 - With the possible exception of cell-phone end-users (who have
    telco-provided operating systems and applications on their
    devices) no ordinary end-users can be happy with their Internet
    service unless it provides full connectivity to "all" other
    Internet hosts, using the full range of applications which
    other Internet users use.

    "All" means something close to 100%.  Maybe 99.9% or so -
    certainly a very high proportion.


3 - Due to the use of a large variety of application protocols,
    including many game protocols, those using UDP, P2P protocols
    etc. it is entirely infeasible to construct any kind of gateway
    or proxy system between IPv4 and IPv6.  Furthermore, the
    protocols are not necessarily amenable to proxying etc. and
    the applications generally have no facility for using a proxy.


4 - Before point 2 could be achieved, a very large proportion of
    end-users would need to adopt IPv6 while they use IPv4.  This
    would require many things, including:

     a - ISPs providing both IPv4 and IPv6 space and services.

     b - Easy administration of hosts, routers etc. for handling
         both types of addresses and traffic at once.

     c - Mature, robust, OS support for IPv6 in "all" operating
         systems used by "all" end-users - not just their desktop
         and server computers, but their printers, DSL modems,
         WiFi boxes, VoIP boxes, managed Ethernet switches etc.

     d - "All" (or at least a very high proportion) of applications
         being fully functional in dual stack machines, as well as
         in pure IPv4 and pure IPv6 machines, without glitches or
         extra administration requirements.

    These requirements cannot possibly be met in the near-term, or
    without extreme efforts on the part of application developers -
    and many applications are no longer being developed, so there
    would always be some users who can't do what they want without
    IPv4.


5 - Before there is ubiquitous IPv6 adoption, all the impetus for
    point 4 would need to come from some benefit that IPv6 provides
    for adopters, while they still have IPv4 addresses.

    Currently, there are no such benefits.


6 - Therefore, if IPv6 adoption is to solve the IPv4 routing scaling
    problem in any timeframe such as 2013 or whatever, then a number
    of hurdles must be overcome, including:

    a - Rapid development and deployment of an RRG-suggested
        protocol for IPv6 which will provide a new class of address
        space which can be used for multihoming, TE and portability
        without causing the scaling problems we are trying to solve.

    b - This technology being made available to ISPs and end-users
        in a way by which the end-users gain some convincing
        benefits over the immediate costs and disruption of adopting
        any new system.

    c - By this process, IPv6 adoption growing from essentially zero
        to over 99%, which would provide the essential precondition
        for a significant number of end-users no longer wanting or
        needing IPv4 connectivity or address space.


7 - To achieve this, there would have to be some unique benefits for
    end-users, since they will only adopt IPv6 if it provides
    immediate, direct, benefits.  The characteristics of these
    benefits would need to include:

    a - The benefit could only exist via IPv6 - otherwise, someone
        will make it available via IPv4 and then no end-user would
        have a reason to adopt IPv6.

    b - The benefit must exist in a dual-stack arrangement, since
        until IPv6 adoption is ubiquitous, all end-users will need
        and have IPv4 connectivity.  (Therefore it must be greater
        than whatever burdens dual stack imposes on users,
        administrators and ISPs.)

    c - The benefit must apply to the great majority of end-users.
        If it only applies to some subset, such as those who are
        interested in games, or real-time video, then this would
        not attract the very high proportion of end-users (99.9%
        etc.) which we need in order for any end-users to be able
        to do without IPv4 address space.

    d - The benefit must be directly tied to the new RRG-suggested
        protocols.  Otherwise people could get the benefits via
        IPv6 without the new protocols.

    e - The benefit must be compelling.  Yet it must be something
        which is impossible with most Internet communication -
        which will take place via IPv4 until the 99.9% IPv6 adoption
        makes IPv4 unnecessary.

    f - This benefit must exist from the very start, otherwise
        no-one will adopt it.

    g - The benefit cannot result from greater efficiency or
        reliability, since IPv4's efficiency is greater than that
        of IPv6, and because for the vast majority of end-users,
        IPv4's reliability is perfectly adequate.

    h - The benefit must therefore involve some new application
        capability, or some new service capability, which physically
        can't be done via IPv4 or via IPv6 without the RRG-suggested
        new protocols.

Unless someone has convincing suggestions regarding these benefits,
I believe that there can be no benefit which meets this requirement
- and therefore no way sufficently large numbers of end-users could
be attracted to IPv6 in order to make IPv4 connectivity no-longer
essential for a general purpose Internet service.

Therefore, I argue we need to solve the IPv4 routing scaling problem
directly.

Ideally, the same techniques should solve any future IPv6 routing
scaling problem - however, I think there is no urgency in applying
those techniques to IPv6 as long as its usage remains so low that
the system is far from hitting scaling limits.

  - Robin          http://www.firstpr.com.au/ip/ivip/


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