Rfc6417
TitleHow to Contribute Research Results to Internet Standardization
AuthorP. Eardley, L. Eggert, M. Bagnulo, R. Winter
DateNovember 2011
Format:TXT, HTML
Status:INFORMATIONAL






Independent Submission                                        P. Eardley
Request for Comments: 6417                                            BT
Category: Informational                                        L. Eggert
ISSN: 2070-1721                                                    Nokia
                                                              M. Bagnulo
                                                                    UC3M
                                                               R. Winter
                                                              NEC Europe
                                                           November 2011


     How to Contribute Research Results to Internet Standardization

Abstract

   The development of new technology is driven by scientific research.
   The Internet, with its roots in the ARPANET and NSFNet, is
   no exception.  Many of the fundamental, long-term improvements to the
   architecture, security, end-to-end protocols and management of the
   Internet originate in the related academic research communities.
   Even shorter-term, more commercially driven extensions are oftentimes
   derived from academic research.  When interoperability is required,
   the IETF standardizes such new technology.  Timely and relevant
   standardization benefits from continuous input and review from the
   academic research community.

   For an individual researcher, it can however be quite puzzling how to
   begin to most effectively participate in the IETF and arguably to a
   much lesser degree, the IRTF.  The interactions in the IETF are
   much different than those in academic conferences, and effective
   participation follows different rules.  The goal of this document is
   to highlight such differences and provide a rough guideline that will
   hopefully enable researchers new to the IETF to become successful
   contributors more quickly.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This is a contribution to the RFC Series, independently of any other
   RFC stream.  The RFC Editor has chosen to publish this document at
   its discretion and makes no statement about its value for
   implementation or deployment.  Documents approved for publication by
   the RFC Editor are not a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.





RFC 6417            Contributing Research to the IETF      November 2011


   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6417.

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.

Table of Contents

   1. Introduction ....................................................3
   2. Is the IETF the Right Venue? ....................................4
   3. How to Get the IETF to Start Work on Your Proposal? .............6
      3.1. Identify the Right Part of the IETF ........................6
      3.2. Build a Community ..........................................6
      3.3. Outline Your Protocol ......................................7
      3.4. Establish a New Working Group ..............................8
   4. How to Increase the Chances that the IETF Successfully
      Standardizes Your Proposal ......................................8
      4.1. Commit Enough Time, Energy, and Perseverance ...............8
      4.2. Be Open and Focus Out ......................................9
      4.3. Seek Resolution, Not Perfection ...........................10
      4.4. Implement .................................................10
   5. Examples .......................................................11
      5.1. Multipath TCP .............................................11
      5.2. Congestion Exposure .......................................12
   6. Security Considerations ........................................13
   7. Acknowledgments ................................................13
   8. Informative References .........................................13














RFC 6417            Contributing Research to the IETF      November 2011


1.  Introduction

   In telecommunications, standards are essential.  More often than not,
   technology interoperability requires an agreement on a single
   standard for a given problem.  However, unlike most research,
   standards developments are driven by particular real-world problems
   and require solutions that are not only theoretically correct, but
   need to be implementable with state-of-the-art technology in a cost-
   effective manner, and must be incrementally deployable in the actual
   Internet by the involved stakeholders.  In other words, standards
   should be both theoretically correct and practically applicable.  In
   the academic world, the former is often more important than the
   latter!

   In the IETF, a practically applicable solution that has some well-
   defined and acceptable deficiencies trumps a theoretically complete
   and optimal solution that cannot be deployed.  Likewise, a solution
   to an interesting theoretical problem that does not exist in the
   deployed Internet at large does not require urgent standardization.
   Finally, standardization oftentimes focuses on piecemeal improvements
   to existing technology in order to enhance secondary aspects, which
   does not excite an academic researcher looking to solve juicy
   problems.

   These differences between academic research and Internet
   standardization are the main reason why many researchers initially
   struggle when they begin to participate in the IETF.  Symptoms of
   this struggle occur, for example:

   o  for ideas that are too far outside the IETF's areas of current
      work

   o  for ideas that are too high-level for the IETF to begin protocol-
      level work on

   o  for proposals that solve problems that are not expected to arise
      for a very long time

   o  if there is a reluctance to give others a say in how a research
      idea is being made concrete, or giving over change control
      entirely

   o  if there is a feeling that the IETF "does not listen" to them or
      does not have "the right people"

   o  if there seems to be no working group or other venue to bring the
      work to




RFC 6417            Contributing Research to the IETF      November 2011


   o  if the researchers are not interested in topics such as security,
      performance, and operational management -- topics that the IETF
      will consider carefully

   o  when the process seems too time consuming

   o  when the researchers do not have the resources to keep the IETF
      effort active for an extended period of time

   o  if there is not a convincing enough argument for the IETF to start
      working on something, despite great simulation results

   o  if the research idea is just not implementable in today's Internet

   This document attempts to give some basic advice that researchers
   might want to take into account when deciding to approach the IETF
   with their ideas, in order to improve their success probability.  It
   is intended to complement the more general advice in [RFC4144] about
   "How to Gain Prominence and Influence in Standards Organizations".
   Other, more general advice and detailed explanations of the structure
   and inner workings of the IETF can be found in "The Tao of IETF"
   [RFC4677].

   The authors have been involved in several research projects,
   including collaborative ones, which have sought to standardize some
   of their results at the IETF, and we hope to pass on some advice
   (sometimes that we have learned the hard way!).  The advice is split
   into three groups: before you approach the IETF; how to get the IETF
   to start work on your proposal; and finally how to increase the
   chances of success once work has begun.

2.  Is the IETF the Right Venue?

   A researcher should consider whether the IETF is the right venue
   before bringing a proposal to it.  A way to do so is to imagine that
   the IETF has standardized your proposal and it has been deployed, and
   ask yourself two questions:

      1. How would the Internet be better?

      2. What Internet nodes would have been upgraded?

   It is very important to have a clear explanation about the motivation
   for your proposal: what would its benefits be?  What problem does it
   solve?  Many ideas do not bring a clear benefit to the Internet in
   the near term (of course they may still be fine pieces of research!).
   In the past, the IETF has often developed protocols that ended up not
   being used, so it now thinks harder about the benefits before



RFC 6417            Contributing Research to the IETF      November 2011


   starting new work and makes sure that it solves a current,
   significant problem rather than one that may theoretically arise in
   the future.  It is best to be specific about what improvement your
   proposal would make and the use cases in which this would be seen.

   It is also important to have a simple description of what additions
   or changes are needed and to which nodes (be they end-hosts, routers,
   middleboxes, etc.).  Is it substituting for an existing IETF protocol
   or supplementing one?  Again, it is best to be specific: Do both ends
   need to adopt the new protocol?  Can it fall back or interoperate
   with the existing IETF protocol?  Do the "first movers" (the first
   nodes that include your protocol) get an improvement, or do the "last
   movers" gain most?  What assumptions do you make about the network or
   host (perhaps that the host is multi-homed or there are no
   middleboxes on the path)?  While thinking about these things, it is
   also worthwhile considering operational practices and business
   models.  If you will likely break some of these, you will inevitably
   face some opposition in the IETF.

   If it is hard to answer these questions, it may indicate that the
   idea is too high-level or abstract for the IETF.  Then it may be
   better to approach the IRTF (the research arm of the IETF); the IETF
   needs a specific protocol-level proposal before it can begin work,
   while the IRTF considers work that is not yet mature enough for
   standardization.  Another danger is that the IETF is the wrong
   standards body, as a different one would need to standardize your
   proposal.

   If your idea involves replacing several IETF protocols and/or
   upgrading several types of nodes simultaneously, it is probably best
   to rethink: the IETF finds it almost impossible to handle radical,
   "clean slate" proposals that change lots of things at once.  Perhaps
   you can trim off a subset of your idea that's a smaller initial step
   requiring only an incremental change to an existing protocol, but you
   need to consider whether it is still useful.

   Finally, before bringing a proposal to the IETF, you need to be aware
   that there are intellectual property implications.  For example, it
   will affect any patents you want to file.  Less obviously, you grant
   the IETF the right to publish your contribution and you should inform
   the IETF if your proposal is covered by a patent.  For more
   information about the rights you grant to the IETF, the best thing to
   read is the IETF's "Note Well" [NoteWell] and the documents linked to
   from there.







RFC 6417            Contributing Research to the IETF      November 2011


3.  How to Get the IETF to Start Work on Your Proposal?

   Having decided that the IETF is the right venue, you now need to
   persuade the IETF to start work on your idea.  We discuss three steps
   that should help; they can be done in parallel.  We then briefly
   discuss how to form a new working group (WG), if that is necessary.

3.1.  Identify the Right Part of the IETF

   The IETF is a large organization; therefore, you need to communicate
   with the right part of it.  The IETF is organized in areas such as
   routing, security, or transport.  Within those areas, working groups
   are responsible for a specific topic.  The IETF consists of over 100
   WGs.  So, a good step is to identify whether there is already a WG
   suitable for your work.

   If yes, then join the WG's mailing list and send email and perhaps
   write an Internet-Draft.  A WG's current set of specific items is
   defined in its "Charter"; be aware that if your proposal falls
   outside the WG's current charter, then it would have to be extended
   before formal work could begin.  Most WGs think about re-chartering
   every year or two, although most allow for some limited discussion on
   items outside their current charter.

   If no suitable WG exists, then you should identify the right Area.
   The WGs are clustered into "Areas" with a common theme such as
   security, with one or two Area Directors in charge of each Area.  You
   may have to get a new WG created within the most relevant Area; this
   is a significantly difficult step (see below).

   Finding the right WG is akin to finding the right conference or
   journal to submit to.  While a poor choice of conference will get
   your paper rejected as irrelevant, the IETF is friendlier, as most WG
   Chairs and Area Directors will try to redirect your work to a better
   WG, if you choose poorly.  However, ending up with the right "venue"
   is critical, as only then will you collaborate with the right group
   of people.

3.2.  Build a Community

   Standards require agreement and approval by a wide range of people.
   Therefore you need to persuade others of the merits of your idea.  In
   practice you need to go further and persuade others to do work.  At a
   minimum, this will be to thoroughly review your proposal and
   preferably it will be to develop and test it with you.  The IETF
   community needs to see evidence of wider support, interest, and
   commitment.  A lack of reaction means work will not go forward
   (silence is not consent!).  At an early stage, support could be



RFC 6417            Contributing Research to the IETF      November 2011


   demonstrated through comments on the mailing list.  It is a very good
   idea to have some Internet-Drafts jointly authored with people from
   beyond your research team, perhaps an industry player.  For example,
   you could develop a "use cases" document with a "user", such as an
   operator.

   Working with others has the extra benefit that it will help to
   clarify your idea and explain better its benefits and how it works.
   There are many experts in the IETF who can help stress test the idea
   technically and advise about process and culture.  You need to get
   some of them involved as early as possible.

   It may well be worth trying to hold an informal session at an IETF
   meeting.  This can help build a community of interest for your idea;
   see the advice in [BAR-BOF].

3.3.  Outline Your Protocol

   You also need to describe your proposal in a way that others can
   understand.  Your initial document should outline the protocol.  It
   is counter-productive to detail every aspect, unless the protocol is
   incredibly simple.  Firstly, too much detail swamps people with
   information that they cannot process.  Most people understand things
   by learning about them several times at increasing levels of detail.
   Secondly, providing only an outline makes people feel that they have
   a chance of making worthwhile suggestions and changes, so they are
   more likely to actively engage with you.  Thirdly, working out
   details is generally something that a wider group of people is better
   at than an isolated individual.  Fourthly, in order for the IETF to
   start work, it is more important to convince the IETF that there is a
   problem that it needs to solve than to convince it about the merits
   of your solution.

   A good idea is to document a "protocol model", as described in
   [RFC4101]: "a short description of the system in overview form ... to
   answer three basic questions: 1. What problem is the protocol trying
   to achieve?  2. What messages are being transmitted and what do they
   mean?  3. What are the important, but unobvious, features of the
   protocol?"

   It is best to send your contributions in the form of an Internet-
   Draft (I-D).  While it may seem a burden to convert your nice paper
   or slides into the idiosyncratic format of an I-D, this is the format
   that IETF people are used to reading.  Also, extracting the IETF-
   relevant parts of publications into an I-D will often help to
   identify aspects that need more work by the IETF, such as protocol
   details glossed over.




RFC 6417            Contributing Research to the IETF      November 2011


3.4.  Establish a New Working Group

   You only need to establish a new WG if the idea falls outside the
   scope of existing WGs.  Establishing a new WG nearly always requires
   a specific session, called a "BoF" (Birds of a Feather), at one of
   the IETF's face-to-face meetings.  Here the pros and cons of the
   proposed WG are debated.  As part of the preparation for the BoF, you
   need to:

   o  Build a community (see above)

   o  Document the benefits: for example, a problem statement and/or use
      cases

   o  Document the architecture: for example covering assumptions and
      requirements on a solution

   o  Suggest specific work items for the proposed WG, typically the
      protocol to be standardized and the supporting informational
      documents

   Getting approval to hold a BoF and running a successful BoF meeting
   are both quite difficult.  Working with someone experienced and
   reading the guidance in [RFC5434] are highly recommended.

4.  How to Increase the Chances that the IETF Successfully Standardizes
    Your Proposal

   Congratulations, you got the IETF to agree to start working on your
   proposal.  Now it only remains to do the actual work!  In this
   section, we give some advice about ways of working that will increase
   the chances that the standardization runs smoothly.

4.1.  Commit Enough Time, Energy, and Perseverance

   Those new to standards bodies may be surprised how long and how much
   effort it takes to standardize something.

   Success at the IETF requires active participation: to convince others
   your idea is worthwhile, to build momentum, to gain consensus.
   Although IETF work is done mainly through mailing lists, in practice,
   face-to-face time is critical, especially for new or substantial
   work.  If possible, go to the three IETF meetings a year.

   It takes quite a long time for a proposal to turn into an IETF
   standard, even if the proposal is mature when it is first presented.
   There are many steps: building a community of interest, convincing




RFC 6417            Contributing Research to the IETF      November 2011


   the IETF to start work, working through suggestions from technical
   experts and incorporating their improvements, gaining consensus,
   getting detailed reviews (any IETF publication gets significantly
   more reviews than an academic publication), going through the formal
   IETF approval process, and so on.  Even if you can work full time on
   the proposal, effort is required from other people who can't.  Also,
   the IETF tends to work in intensive bursts, with activity
   concentrated in the run-up to and then at the IETF meetings, with
   lulls of low activity in between.

   The IETF proceeds by "rough consensus".  Unlike some other standards
   bodies, there is no voting and no top-down process from requirements
   to architecture to protocol.  The downside of this is that the IETF
   is not good at making decisions.  Hence you need to persevere and
   guard against decisions unwinding.  On the other hand, if the
   consensus is to reject your proposal or there is little interest in
   it, persevering is likely to be a waste of time -- you should
   probably give up or restart at Section 2.

   All this means that it takes a considerable length of time to
   complete something at the IETF.  Two years is probably a minimum.
   So, although a typical three-year research project sounds like plenty
   of time to do standardization, if you haven't already raised the idea
   within the first year, you're probably too late to complete
   standardization before your project ends.  Since it's quite likely
   that IETF standardization won't be finished when your project ends,
   it is particularly important to convince others to help, so that the
   work is more likely to be completed afterwards.

4.2.  Be Open and Focus Out

   It is helpful to come to the IETF with an open mind-set.

   Co-authorship is good.  Some standards bodies value trophy authors,
   who indicate their support but don't actually do any work.  In the
   IETF, it is much better if co-authors are actually investing cycles
   on developing the proposal, whereas simple indications of support can
   be made on the mailing list or at the meetings.

   In particular, if the IETF is going to standardize something, then in
   effect, it takes ownership; it is no longer "yours".  Indeed, a good
   milestone of success is when your individual document becomes a WG
   draft, as then it is owned by the WG.  The research mentality is a
   bit different, as it prizes authorship and confidentiality until
   publication.

   It is very important to be open to working with others.  One specific
   reason is to get help on aspects beyond your expertise or beyond what



RFC 6417            Contributing Research to the IETF      November 2011


   you've had time to think about -- perhaps how to make your protocol
   more secure, or how to ensure it is congestion-friendly, or how it
   impacts network management.  The IETF ensures that any protocol it
   standardizes has thought carefully about such aspects.

   Also, the IETF works by collaboration.  For example, there may be two
   proposals to solve a problem.  In academia their proponents may treat
   each other as rivals and for example write "related work" sections
   that point out flaws and shortcomings of the opposition.  At the
   IETF, they will soon work together on a common document, typically a
   synthesis of the competing proposals, and be sensitive to each other
   in order to help build consensus.  You will also have to get support,
   or at least not vehement opposition, from IETF people working on
   other topics.  So you need to be aware of what else the IETF is doing
   (in case your proposal conflicts) and what other problems exist in
   the Internet today (in case your proposal exacerbates them).

   Finally, collaborative research projects sometimes find it difficult
   to be open to working with others.  Firstly, such projects typically
   have a consortium agreement about confidentiality -- it must not
   prevent you from engaging properly day-to-day with people outside the
   project.  Secondly, you may have to spend considerable effort on
   intra-project coordination -- but, an individual researcher only has
   so much energy and enthusiasm for collaborating, so if you spend a
   lot of time liaising between different groups within your project,
   then you have little left for working with the IETF.

4.3.  Seek Resolution, Not Perfection

   The research mind-set is often to investigate very thoroughly all
   possible details about an idea -- to seek perfection -- sometimes
   with no particular deadline.  The IETF mind-set is to get something
   done and out there that works, albeit imperfectly; if people find it
   useful, then there will be another iteration to improve it, probably
   to meet needs that only become apparent on widescale deployment.  The
   philosophy is to find a reasonable solution to the problem that
   currently exists.  Time spent over-optimizing may simply mean that
   the solution has been superseded (perhaps the problem has been solved
   in some other way, or perhaps the problem was so significant that a
   different approach had to be found to avoid the problem).

4.4.  Implement

   The IETF is very impressed by actual implementations: "running code".
   It helps smooth the standards process, it helps people believe it
   really works, and it helps you and others discover any issues.  An
   implementation that others can download and try is extremely helpful
   in getting your protocol actually deployed -- presumably, that is



RFC 6417            Contributing Research to the IETF      November 2011


   your real objective, not simply to get an IETF standard!  In the
   longer term, you may need to think about how to get it incorporated
   in the Linux kernel, for instance.

   Overall, it is very hard to get a protocol in actual widespread use.
   There are far more IETF protocols on paper than in use.

5.  Examples

   In this section, we include some examples in which the authors have
   been deeply involved and have managed (we believe) to bring the
   research output of a collaborative research project successfully into
   the IETF.

5.1.  Multipath TCP

   Multipath TCP (MPTCP) enables a regular TCP connection to use
   multiple paths simultaneously.  It extends TCP to allow the use of
   multiple IP addresses by each endpoint.  This work is one output of
   the Trilogy research project which was brought to the IETF for
   standardization, and it is currently making good progress.  We
   provide a brief overview of the steps taken.

   The first stage was doing some early socialization of the main ideas
   of MPTCP.  Presentations were made in several relevant WGs: the
   Routing Research Group (July 2008) and the Transport Area Open
   meeting (July 2008 and March 2009).  In addition, a mailing list was
   created, open to anyone who was interested in discussing Multipath-
   TCP-related issues in the IETF context, and a public Web page was
   created containing Multipath-TCP-related material, including papers,
   Internet-Drafts, presentations, and code.  The feedback received was
   encouraging enough to continue with the effort of bringing the work
   to the IETF.

   Once we verified that the proposed ideas had potential traction in
   the IETF, the next step was to identify the proper venue for the
   proposed work.  There were two choices, namely, to go for a BoF, with
   a view to a new WG, or to try to add additional work items to an
   existing WG, in particular TCPM seemed a good candidate.  After
   talking to the Area Directors, it seemed that having a BoF was the
   right approach, at least for the initial discussion stage.  So, a BoF
   proposal was submitted to the Transport ADs for the IETF 75 meeting
   held in Stockholm in July 2009.  The initial BoF proposal was crafted
   by Trilogy people, but was sent to the open mailing list for
   discussion and modification from the rest of the community.  The BoF
   request was approved and the MPTCP BoF was held at the IETF 75
   meeting.




RFC 6417            Contributing Research to the IETF      November 2011


   The general feedback received during the BoF was that there was
   enough interest and energy in the community to do this work within
   the IETF.  A first charter draft was posted on the mailing list for
   comments a couple of months after the BoF.  After a month or so of
   charter discussion on the mailing list, the MPTCP working group was
   created in October 2009.  The charter includes deliverables due to
   March 2011.

   The MPTCP working group has, so far, made significant progress and
   most of the milestones have been delivered on schedule [MPTCP].

5.2.  Congestion Exposure

   Congestion Exposure enables sending end-hosts to inform the network
   about the congestion encountered by previous packets on the same
   flow.  This allows the network devices to act upon the congestion
   information and the perceived user behavior.  Like the MPTCP work, it
   is an output of the Trilogy research project and has been
   successfully brought to the IETF.  We next describe the steps
   followed to do so.

   In this case, early socialization included presentations at the
   Internet Congestion Control Research Group and the Internet Area
   meeting at the IETF 75 meeting in July 2009, the creation of an open
   mailing list to discuss Congestion Exposure related issues in the
   IETF, and posting the related materials such as papers, Internet
   drafts, and code in a public web page.  In addition, an informal,
   open meeting (sometimes called a Bar-BoF in IETF parlance) was held
   during the IETF 75 meeting.

   After processing the feedback received in the Bar-BoF, a BoF proposal
   was submitted to the Internet Area ADs for the IETF 76 meeting in
   November 2009.  The BoF was accepted and was held as planned.  While
   the feedback received in the BoF was positive, the IESG was uncertain
   about chartering a working group on this topic.  (The IESG is the
   IETF's management body and consists of all the Area Directors.)  In
   order to address the remaining concerns of the IESG, another BoF was
   held at the following IETF meeting.

   After much debate, the CONEX WG was approved by the IESG, but the
   scope of its charter was limited compared with the original proposal.
   This was due to some concerns regarding the proposed allocation of
   the last bit in the IPv4 header.  The CONEX WG serves as a good
   example to illustrate the kind of compromise that is necessary when
   research aspiration meets Internet standardization.  The CONEX WG
   [CONEX] held its first meeting at the IETF 78 meeting in July 2010.
   Its charter contains deliverables through November 2011.




RFC 6417            Contributing Research to the IETF      November 2011


6.  Security Considerations

   This document has no known security implications.

7.  Acknowledgments

   Part of this work was funded by the Trilogy Project [TRILOGY], a
   research project supported by the European Commission under its
   Seventh Framework Program.

   Similar material was accepted for publication in ACM CCR, July 2011
   [CCR].

8.  Informative References

   [BAR-BOF]   Eggert, L. and G. Camarillo, "Considerations for Having a
               Successful "Bar BOF" Side Meeting", Work in Progress,
               August 2011.

   [CCR]       "How to Contribute Research Results to Internet
               Standardization".  Marcelo Bagnulo, Philip Eardley, Lars
               Eggert and Rolf Winter.  ACM Computer Communication
               Review (CCR), Vol. 41, No. 3, July 2011.

   [CONEX]     "Congestion Exposure working group",
               http://tools.ietf.org/wg/conex/.

   [MPTCP]     "Multipath TCP working group",
               http://tools.ietf.org/wg/mptcp/.

   [NoteWell]  "Note Well", http://www.ietf.org/about/note-well.html.

   [RFC4101]   Rescorla, E. and IAB, "Writing Protocol Models", RFC
               4101, June 2005.

   [RFC4144]   Eastlake, D., "How to Gain Prominence and Influence in
               Standards Organizations", RFC 4144, September 2005.

   [RFC4677]   Hoffman, P. and S. Harris, "The Tao of IETF - A Novice's
               Guide to the Internet Engineering Task Force", RFC 4677,
               September 2006.

   [RFC5434]   Narten, T., "Considerations for Having a Successful
               Birds-of-a-Feather (BOF) Session", RFC 5434, February
               2009.

   [TRILOGY]   "Trilogy Project", http://www.trilogy-project.org/.




RFC 6417            Contributing Research to the IETF      November 2011


Authors' Addresses

   Philip Eardley
   BT
   Adastral Park, Martlesham Heath
   Ipswich
   England

   EMail: philip.eardley@bt.com


   Lars Eggert
   Nokia Research Center
   P.O. Box 407
   Nokia Group  00045
   Finland

   Phone: +358 50 48 24461
   EMail: lars.eggert@nokia.com
   URI:   http://research.nokia.com/people/lars_eggert/


   Marcelo Bagnulo
   Universidad Carlos III de Madrid
   Av. Universidad 30
   Madrid
   Spain

   EMail: marcelo@it.uc3m.es


   Rolf Winter
   NEC Europe
   Heidelberg
   Germany

   EMail: rolf.winter@neclab.eu