Robin,
Thank you very much for your questions. I'll try to answer some of
your questions. Lixia and other members of our team will add their
comments.
On Jan 31, 2010, at 6:55 PM, Robin Whittle wrote:
Hi Lixia,
Thanks for pointing out (in an off-list message) that I had
mischaracterised the goals of "Aggregation with Increasing Scopes: An
Evolutionary Path Towards Global Routing Scalability".
I wrote (msg05835) that this proposal was aimed at "Improving router
utilization as a prelude to adopting a solution". My description in
msg05835 was also inaccurate except for my note that it:
suggests it is near-term preliminary to a longer-term
host-based solution - implicitly a Core-Edge Elimination scheme.
Your interpretation is not exactly what we meant to say. We aim to
solve the routing scalability problem both in the near term and in
the long term through increasing scope of aggregation. The following
paragraph from our proposal says that our solution is orthogonal to a
host-based solution. Since a host-based solution will not solve the
routing scalability problem until a large portion of the Internet
hosts adopt it, we still need a short-term solution (in our proposal,
the first two steps FIB aggregation and Virtual Aggregation will
serve this purpose). If a host-based solution never gets widely
deployed, the later steps in our proposal (e.g. inter-AS VA) will
address the long-term scalability needs.
A major consideration for our work is incremental deployability and
immediate scalability benefit to anyone who adopts our scheme. You
may recall that we started with a map-and-encap scheme APT, which
falls into the core-edge separation category. However, during the
past couple of years working on APT, we realized that it is difficult
for a single entity to deploy APT and receive immediate benefit. Our
work has evolved based on this understanding.
This is based on this passage from the PDF version of the proposal:
Note that our proposal neither interferes nor prevents
any revolutionary host-based solutions such as ILNP from
being rolled out. However, host-based solutions do not
bring useful impact until a large portion of hosts have
been upgraded. Thus even if a host-based solution is
rolled out in the long run, an evolutionary solution is
still needed for the near term.
I apologise for these misleading descriptions, which were based on
only partially reading the proposal.
The RRG Report mentions only two of the three documents:
The Virtual Aggregation presentation:
http://tools.ietf.org/agenda/76/slides/grow-5.pdf
The ID:
http://tools.ietf.org/html/draft-zhang-evolution-02
but does not mention the PDF file:
http://www.ietf.org/mail-archive/web/rrg/current/pdfkyygpVszbl.pdf
which was posted to the list in (msg05550). The RRG wiki link is
only to the PDF file.
The PDF file on the RRG wiki page is our 2-page summary, as requested
by the chairs. The ID http://tools.ietf.org/html/draft-zhang-
evolution-02 provides more information. It is cited in the 2-page
PDF file. The ID contains a more detailed description of the
mechanisms.
Due to caching constraints, I do not plan to read these fully until I
have tackled the other proposals. Based on my partial reading, here
are some questions which I hope you will be able to answer:
1 - What are the goals of AIS? How many non-mobile end-user
network prefixes do you plan the system to scale to?
Brian Carpenter and I have both, independently, suggested
that 10 million such networks should be a goal.
Our main goal is to scale routing (i.e. FIB size, RIB size, update
rate). We're not aiming at a specific size, and I don't think
there's a specific upper size limit for our approach. One reason is
that there are engineering trade-offs involved. We have some
evaluation results in a submitted paper.
I think we must all expect that in the foreseeable future -
to 2020 or 2025 - that the majority of hosts will be mobile
hand-held devices. There really needs to be a mobility system
so they can continue their sessions despite gaining and losing
multiple addresses in various access networks - including IPv4
addresses behind NAT, such as by using WiFi in homes and
offices. I think we should consider 10 billion of these the
upper limit.
"Mobility" is not mentioned in your proposal. To what extent
is AIS intended to support large-scale mobility?
Our position for mobility support is that it is best provided by
mechanisms outside the routing system. Here's a paper that
describes the supporting arguments: "Support Mobility in the Global
Internet", Lixia Zhang, Ryuji Wakikawa, Zhenkai Zhu. http://
www.cs.ucla.edu/~lixia/papers/micnet09.pdf
I'll send another email to answer your remaining questions.
Lan
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