In einer eMail vom 20.07.2008 03:14:58 Westeuropäische Normalzeit schreibt
rw@firstpr.com.au:
Here are
my thoughts on the current and recent scope of this discussion
list.
It seems it doesn't matter much how compatible a potential
solution is with reality. As long we can discuss it in theoretical
terms, without getting into messy technical details, then it can be
in scope for the RRG.
Meanwhile, we are not supposed to discuss
potentially practical proposals - or to discuss anything in the detail
required to test its compatibility with business needs, technical
limitations etc.
We have been directed not to discuss actual
proposals and to focus on "architectural" issues (implicitly "higher
level") instead of "engineering":
http://psg.com/lists/rrg/2008/msg01551.html (Lixia)
> - my notion of the RRG task is to develop an
architectural > solution to routing
scalability. > > - We should step up a level
from looking specific versions of > IP at this stage
of solution development. Our solution has > to
be an architectural change, and should work for either >
version.
Discussing LISP, APT, Ivip, TRRP or Six-One Router is
out of scope.
http://psg.com/lists/rrg/2008/msg01285.html
(Tony)
> Now, can we please stop discussing
proposals?
Mobility is out of scope for now:
http://psg.com/lists/rrg/2008/msg00815.html
The focus is on major
change, to last "indefinitely" - "effectively forever", rather than
"band-aid" approaches:
http://psg.com/lists/rrg/2008/msg01559.html (Tony)
> It seems likely that if we do in fact make a shift to v6,
then > it would be effectively forever or at least long
enough to > exceed the life span of anyone currently on the
mailing list. > I'd very much prefer that we left our
grandchildren something > that we could all be proud
of.
and a "clean" approach:
http://psg.com/lists/rrg/2008/msg01564.html (Tony)
> My version of 'clean' is much strong than just meeting
the > design goals. It also has to do with
complexity, overhead, > fit, and harmony.
But this
does not suit people who want to discuss IPv4, IPv6 and clean slate
proposals in parallel.
IPv4 and IPv6 solutions are in
scope:
http://psg.com/lists/rrg/2008/msg01539.html
however discussions are to
be directed towards an IPv6 solution, with perhaps an IPv4 solution as a
secondary consideration:
http://psg.com/lists/rrg/2008/msg01535.html (Tony - rough consensus
2008-05-13)
> |Our recommendation should be applicable
to IPv6. It may or > |may not also apply to IPv4, but
at the very least must provide > |a path forward for
IPv6. > > It's my judgement that we have rough
consensus on this. There > is dissent, notably from
Robin and Bill, but overall, it seems > that we have rough
consensus.
http://psg.com/lists/rrg/2008/msg01559.html
(Tony)
> If we do find something that is both clean AND
can be > back-ported to v4, I would definitely support
that.
Yet there is insufficient attention to the differences between
IPv4 and IPv6:
http://psg.com/lists/rrg/2008/msg01551.html (Lixia)
> IPv4/v6 share the same architecture; the only major
fundamental > difference is their address space
size. > > Our solution has to be an
architectural change, and should > work for either
version.
There are immense differences between IPv4 and IPv6 when it
comes to developing a scalable routing solution. IPv6 has a much
lower installed base, much greater address space capacity, 4 times
the number of bits to play with etc.
The address differences make
Six-One Router potentially practical for IPv6 and completely impractical
for IPv4. The address length differences mean that map-encap schemes
have a much higher encapsulation overhead for IPv6 than for IPv4.
Six-One Router has no such overheads. (I am not convinced the IPv6
solution must be in principle the same as the IPv4
solution.)
Recently Heiner, Iljitsch and Tony have promoted
discussion of geographically aggregated addresses. This is a
scalability fix which requires ISPs and end-user networks behave as if they
did not need certain things they do need - in order that the routers have
an easy task.
http://psg.com/lists/rrg/2008/msg01815.html (Bill showing Heiner's
proposal can't meet business needs.)
http://psg.com/lists/rrg/2008/msg01829.html BH
http://psg.com/lists/rrg/2008/msg01859.html RW
Tony perhaps
admitted that geo-aggregation was more of academic than practical
interest:
http://psg.com/lists/rrg/2008/msg01860.html
> My point was an
academic one: if it was possible to get some > degree of
multi-lateral cooperation from providers, then > geo-aggregation
at a very coarse level with relaxed rules is > _technically_
feasible.
Geo-aggregation is technically feasible because it is a
technical no-brainer. There is no need for new engineering - either
new router functions or any overlay network such as map-encap
or translation (Six-One Router) schemes etc.
Geo-aggregation
couldn't be applied to IPv4, so this is a scheme for a radically revised
IPv6, or a clean-slate architecture. So it could only help with the
routing scaling problem if we could wean most users off IPv4 onto a
completely new and incompatible Internet.
All the work of
geo-aggregation is in the fields of mathematics, address administration and
in marketing/enforcement - somehow convincing all ISPs and end-user
networks to adopt its onerous restrictions on addressing, connections
between networks, the traffic they need to handle for other networks
etc. This last aspect is and will surely remain
impossible.
So the fact that a proposal is completely impractical
is not a problem for the RRG.
The fact that discussions involve real
technical details - as does any useful discussion of LISP, APT, Ivip, TRRP,
Six-One Router etc. - IS a problem for the RRG.
It is apparently
fine to discuss things on the RRG list as long as we steer well clear of
the messy details of how something would work in the current version of
reality.
The RRG's scope prevents us from discussing IPv4-specific
solutions, despite the facts:
1 - The IPv4
Internet is the only Internet with a routing
scaling problem. and 2 - IPv4 is the
Internet which is relied upon by all users.
So I think the RRG list
is not suitable for discussing the practical aspects of any proposal, or
any proposal which is directed to solving the IPv4 problem soon and to
solving any IPv6 problem if and when one occurs.
Meanwhile, time
ticks by, the DFZ routing table keeps on growing:
http://bgp.potaroo.net
TCAM FIB routers become obsolete:
http://psg.com/lists/rrg/2008/msg01851.html
or at least very tricky to
use in the DFZ.
The March 2009 (RRG reporting deadline) approaches and
we have achieved consensus on next to nothing.
The RAM list is
closed:
http://www.ietf.org/mail-archive/web/ram/current/msg01895.html
and
discussions beyond the scope of the RRG are directed to
the architecture-discuss list:
https://www1.ietf.org/mailman/listinfo/architecture-discuss
which has
had no substantial activity since 2007-05. The scope
of architecture-discuss specifically precludes discussion of the
sorts of details which make or break actual solutions:
Discussions that drill down and dwell on specifics of
individual protocols or technologies are to be discouraged,
redirected to appropriate other fora, or re-cast to
discussions of broader implications for Internet
architecture.
This is the state of discussion lists
which concern the fascinating and immensely important question of how to
restructure the Internet's routing and addressing system.
There
seems to be an overly strong focus on high-level "architecture" at the
expense of practical, engineering matters.
I think discussion needs to
involve all these levels. Architecture without sufficient attention
to engineering detail often results in buildings which look "good" (however
defined) on the outside, but with heating and cooling systems which don't
function properly, which are difficult to maintain, with exteriors which
become tatty, and which may not meet the needs of the
occupants.
Network architecture without sufficient attention to
backwards compatibility leads to systems which are far too poorly adopted
to make a difference to the routing scaling problem, e.g.
IPv6.
Maybe clean-slate discussions and those concerning proposals
which are inherently impractical (geo-aggregation) should be on a
separate mailing list from those concerning proposals which are meant to
be practical for IPv4 and IPv6. The IPv4 and IPv6 discussions
are related, and constrained by reality - but clean slate
and theoretical discussions are not so constrained.
I regard radical
revisions of IPv6 - such as changing to GSE or geo-aggregated addressing -
as having the serious adoption hurdles which are typically found with
"clean slate" designs, without the potential benefits of starting
afresh.
- Robin
By means of TARA (topology aggregating routing architecture):
The more remote a link the looser it is, the looser the link the more
stable it is, the more stable the link
the less routing churn occurs, the less routing churn occurs the more time
can be spent on dealing with practical concerns (i.e. OTHER practical
concerns than the scalability problem which will be gone forever)
Heiner
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