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[RRG] Consensus? Users will not adopt solutions which result in "split-system" functionality
- To: Routing Research Group <rrg@psg.com>
- Subject: [RRG] Consensus? Users will not adopt solutions which result in "split-system" functionality
- From: Robin Whittle <rw@firstpr.com.au>
- Date: Sun, 25 May 2008 19:30:13 +1000
- Organization: First Principles
- User-agent: Thunderbird 2.0.0.14 (Windows/20080421)
I am perplexed by several things at this late stage in the RRG
discussion - 19 months after RAWS, 10 months before our deadline,
and after four or five map-encap proposals (LISP-NERD, LISP-ALT,
APT, Ivip and TRRP) have been described in sufficient detail for
there to be robust critiques made of their practicality.
1 - We have achieved consensus on very little:
http://psg.com/lists/rrg/2008/msg01299.html
2 - We are now being asked to decide whether or not certain
parts of the design space might contain the preferred
solution, such as Six/One Router as in the "Translation"
part of the space, as opposed to LISP etc. in the
map-encap part. Yet we are being discouraged from discussing
actual proposals: http://psg.com/lists/rrg/2008/msg01285.html
3 - I think the five map-encap proposals were all predicated on the
assumptions (which is reasonable to me, and presumably to
the other developers) that host changes are not practical
and that we must solve the IPv4 routing scaling problem
directly - but now I find that these two assumptions are
not agreed to by some folks, and they are not part of
what we have "consensus" on.
So I feel the need to backtrack even further and suggest we achieve
consensus (actually, "rough consensus" I think) on some more
fundamental things before we can make decisions about which sectors
of the design space might contain the solution the RRG should recommend.
The first of these proposals is in this email. Other messages deal
with other things which I thought we agreed on, and which I think we
must agree on, if we are to make much further progress towards
achieving consensus on where the best solution might lie.
First of all, I want to state some things I think we all agree on -
a series of limitations on "our" ability to encourage or force
anyone to adopt a solution to the routing scaling problem:
1 - The IETF has little persuasive influence on the actions of
of the end-user networks, ISPs etc. who must implement any
technical solution to the routing scaling problem.
2 - Likewise, the RIRs. Likewise the RRG. None of us have
anything more than the ability to present some arguments and
make a case to other parties - although the IETF can develop
some protocols etc. and the RIRs could work together to
administer address space to help facilitate adoption of
the new technologies.
3 - Since any solution which is widely enough deployed to solve
the routing scaling problem must be deployed by end-users etc.
acting in their own short to medium term interests, we need to
devise a solution which will be enthusiastically adopted by
many and later most end-users, ISPs etc. In order for this
to occur, they must gain genuine, direct, benefits over and
above their costs, risks and disruption etc. The fact that
they would be reducing (or not expanding) the DFZ routing
table is not such a benefit.
(However, to the extent that end-users are able to use a new
form of address space which does not contribute to the routing
scaling problem, it is possible that ISPs, RIRs etc. may be
able to supply this space at a lower cost than is currently
possible.)
Based on the above, which I think we all agree on, here is the point
of this message: Can we form consensus on the following?
Short version:
ISPs, end-user networks and end-users will not adopt solutions
which result in "split-system" functionality - at least not
to the very high levels of adoption we need in order to solve
the routing scaling problem.
So any solution to the routing scaling problem must provide
clear benefits to all of the network when it is adopted - not
some complex to administer patchwork of benefit and no benefit.
Long version:
In order for our solution to be attractive, it must result in
immediate benefits. This includes the requirement that the
benefits be system-wide, clear and unambiguous - resulting in
minimal extra complexity, and in significant immediate benefits
which are measurable in ways which lead to greater reliability,
better performance etc. - all "bankable" aspects of system
performance. (That is, direct, useful, benefits to those who
adopt the new technology.)
This would be impossible if the solution only provided a
half-baked set of benefits. For instance, if either or both
of the points below were true, the new technology would
introduce such complexities that it would never be widely
adopted by most end-user networks, ISPs etc. acting in their
own immediate interest:
1 - The solution can only be applied to a subset of their
network. For instance, but not limited to:
The solution involves host OS changes, but it is
impossible, impractical or too costly to upgrade
all hosts in this way.
The solution involves changes to applications -
and it will never be possible to upgrade all
applications, because some are no longer maintained.
Therefore, in adopting the solution, the end-user network
ISP etc. would find their network to be only partially
benefiting, and would be burdened with the added complexity
of having to remember which parts of their system work with
the new solution and which don't.
For instance, if robust multihoming, portability of
address space, TE etc. only works for some of their
hosts, some parts of their network, some of their
applications and not others, then this will be such an
additional burden of complexity that far too few
end-users etc. would actually adopt the solution in
order for the solution to make a sufficiently big impact
on the routing scalability problem.
2 - Even if an entire network could be upgraded completely
(including reliable, easy, secure, upgrades to all hosts)
then if the benefits only arise when communicating with
other upgraded networks, hosts, applications etc. then
the solution will not produce sufficient benefits to
"early" adoptors for it to be widely enough adopted
to make the required impact on the routing scalability
problem.
"Early" means the first adoptor, the first thousand adoptors
and in some senses every adopter as long as some potential
adoptors have not yet done so.
The reason for this is that as long as there is less than
100% adoption, and as long as benefits only materialize when
communicating with upgraded networks, hosts, applications
etc. there will always be a "split-system" situation, in
which the benefits are partial.
Since the benefits concern reliability of reachability - in
multihoming and portability (changing to another ISP)
situations - very few end-users will invest in the costs and
disruption in order to achieve benefits for only a subset
of their traffic. This is true if the subset is 90%, and
even more true if it is 10%. 1% or 0.01%, which would be the
case initially.
- Robin http://www.firstpr.com.au/ip/ivip/
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