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diff --git a/doc/rfc/rfc6417.txt b/doc/rfc/rfc6417.txt new file mode 100644 index 0000000..b0a22d5 --- /dev/null +++ b/doc/rfc/rfc6417.txt @@ -0,0 +1,787 @@ + + + + + + +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. + + + + + +Eardley, et al. Informational [Page 1] + +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 + + + + + + + + + + + + + + +Eardley, et al. Informational [Page 2] + +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 + + + + +Eardley, et al. Informational [Page 3] + +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 + + + +Eardley, et al. Informational [Page 4] + +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. + + + + + + + +Eardley, et al. Informational [Page 5] + +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 + + + +Eardley, et al. Informational [Page 6] + +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. + + + + +Eardley, et al. Informational [Page 7] + +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 + + + + +Eardley, et al. Informational [Page 8] + +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 + + + +Eardley, et al. Informational [Page 9] + +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 + + + +Eardley, et al. Informational [Page 10] + +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. + + + + +Eardley, et al. Informational [Page 11] + +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. + + + + +Eardley, et al. Informational [Page 12] + +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/. + + + + +Eardley, et al. Informational [Page 13] + +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 + + + + + + + + + + + + + + +Eardley, et al. Informational [Page 14] + |