P2PRG L. Caviglione
Internet Draft Senior Researcher
CNIT - Unige
Expires: September 2006 W. Yeager
Chief Scientist
Peerouette,Inc.
March 13, 2006
P2Pv6 (Peer-to-Peer over IPv6) Problem Statement
draft-irtf-p2prg-p2pv6-problem-statement-00.txt
Status of this Memo
By submitting this Internet-Draft, each author represents that
any applicable patent or other IPR claims of which he or she is
aware have been or will be disclosed, and any of which he or she
becomes aware will be disclosed, in accordance with Section 6 of
BCP 79.
This document may only be posted in an Internet-Draft.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html
This Internet-Draft will expire on September 13, 2006.
Caviglione Expires September 13, 2006 [Page 1]
Internet-Draft P2Pv6 Problem Statement March 2006
Copyright Notice
Copyright (C) The Internet Society (2006). All Rights Reserved.
Abstract
IPv6 has some interesting differences if compared to IPv4. Among the
others, it has been developed to restore the end-to-end transparency
of the Internet, it offers effective functionalities to support end-
nodes configuration phases, and it offers many features that are
implemented in IPv4 as add-ons. With such a foundation, IPv6 appears
as an ideal playground for developing Peer-to-Peer (P2P) applications
that rely by design on the interaction between end nodes.
The purpose of this document is to attract participation within the
P2Pv6 research group, in order to establish a coordinated and
proficient research about the joint usage of p2p frameworks and the
IPv6 protocol.
Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [1].
Table of Contents
1. Subgroup Characterization, History and Practices...............3
2. Near Term Goals................................................4
3. Research Roadmap...............................................4
3.1. Provide Support to the IPv6 Deployment....................4
3.2. Analysis of Inferences of P2P and Transitional Mechanisms.5
3.3. Analysis of Legacies......................................5
3.3.1. Implementation Oriented Legacies.....................6
3.3.2. Algorithm Oriented Legacies..........................6
3.4. Augmenting P2P Capabilities Via IPv6 Functionalities......6
3.5. Interoperability Between the P2P Virtual Layer and IPv6...6
3.6. Analogies between IPv6 and P2P Addressing Schemes.........6
4. Subgroup Milestones............................................7
4.1. Additional Considerations on Milestones...................7
5. Intermediate Outcomes..........................................8
5.1. Persistent Infrastructure features inherited from IPv4....8
5.1.1 Strengths of IPv6 and end-to-end transparency............8
6. Related Work...................................................9
7. Liaisons.......................................................9
8. Security Considerations.......................................10
APPENDIX A: Original P2Pv6 Manifest..............................11
Caviglione Expires September 13, 2006 [Page 2]
Internet-Draft P2Pv6 Problem Statement March 2006
9. References....................................................13
9.1. Normative References.....................................13
9.2. Informative References...................................13
Authors' Addresses...............................................14
Intellectual Property Statement..................................14
Disclaimer of Validity...........................................14
Copyright Statement..............................................15
Acknowledgment...................................................15
1. Subgroup Characterization, History and Practices
Briefly, the P2Pv6 subgroup is exploring capabilities and issues that
arise from the joint use of the p2p communication paradigm and IPv6.
The subgroup officially acts inside the IRTF-P2PRG and it is
organized on an open basis. The P2Pv6 main discussions are made over
the general P2PRG mailing list, which is available at p2prg@irtf.org.
The [P2Pv6] tag is REQUIRED, in order to properly identify this topic
among others. The tagging mechanisms have been discussed and approved
in the IRTF-P2PRG Meeting held in Paris, 2005. Interim results and
subsequent documentation will be publicly available from the WG
homepage at:
http://www.cs.umd.edu/projects/p2prg/
The P2Pv6 activity had been originally proposed on the P2PRG main
mailing list. Subsequently, it has been discussed in the IRTF Meeting
held in Paris, 2005. On that occasion, the P2PRG Chairs approved the
activity. The P2Pv6 subgroup was spawned after the discussion.
Furthermore, the P2Pv6 group will reflect the generalized approval of
the P2PRG’s "Near Term Goals", representing the top research
priorities acknowledged by the subgroup members.
Prior to writing this problem statement draft, the subgroup produced
some preliminary discussion traffic about the initial topics
proposal. Such mail traffic is available from the P2PRG mail archives
at:
http://www1.ietf.org/mail-archive/web/p2prg/current/maillist.html
Also, the P2Pv6 subgroup can benefit from the P2PRG Bibliography
Project, which constitutes a collaborative effort among every P2PRG
participant to build a “Knowledge Base” of the available literature
about p2p. P2Pv6 participants are encouraged as well to share
documents and surveys with other P2PRG members. The P2PRG
Bibliography Project is available at:
Caviglione Expires September 13, 2006 [Page 3]
Internet-Draft P2Pv6 Problem Statement March 2006
http://www.cs.umd.edu/projects/p2prg/bib/index.html
2. Near Term Goals
The P2Pv6 subgroup attempts to be in compliance with the Near Term
Goals of the P2PRG:
o Classifying the P2P problem space (both currently, and as it
evolves) into those problems for which there are existing
solutions and those for which solutions require longer-term
development;
o Developing descriptive model(s) of peer-node organization whose
interpretation can be applied to these solutions;
o Articulating the scope as to what sort of P2P applications the
models encompass and what sort they do not;
o Understanding the unique security-related problems and
opportunities P2P systems pose;
o Exploring interfaces to IETF protocols to realize the models;
o Offering input to the IETF as a starting place for possible groups
standardizing new protocols that are useful in building P2P
applications.
3. Research Roadmap
The P2Pv6 has a Research Roadmap can be broadly defined as follows:
3.1. Provide Support to the IPv6 Deployment
P2P applications rely on the end-to-end transparency that originally
characterized the Internet. This action item aims to show how the
IPv6 protocol can provide an excellent environment for P2P-based
applications with the further goal of yielding a "killer-application"
to support the deployment of IPv6. We also envisage putting in place
explicit liaisons with the IPv6 Task Forces.
A primary goal of the P2PRG is to point out the return to end-to-end
connectivity that P2P infrastructures can provide. A key concept for
P2P systems is to permit any two peers to communicate with one
another in such a way that either ought to be able to initiate the
contact. From this perspective, the deployment of IPv6 systems will
be beneficial for P2P applications and could be boosted by the even
more demand for P2P-based frameworks.
Caviglione Expires September 13, 2006 [Page 4]
Internet-Draft P2Pv6 Problem Statement March 2006
3.2. Analysis of Inferences of P2P and Transitional Mechanisms
The wide deployment of IPv4, as well as intrinsic problems of large-
scale transitions, spawned thorough standardization tracks for
defining transitional mechanisms: Transitional mechanisms are
expected to populate the future Internet for a quite long time since
IPv4 and IPv6 are expected to operate simultaneously during this
transitional era.
On top of this scenario, the P2P layer will be required to adapt to
transport layer changes since it is in fact an application layer
interface to the transport layer. These adaptations are critical so
it will operate properly. Given this interface, P2P can then continue
to be viewed as building an “overlay” network, thus yielding a
playground that is isolated from the ongoing transport transitions
and that can be used for developing new applications and services.
We propose to study if the transitional mechanisms developed for
managing the transition and coexistence of IPv4/IPv6 are critical for
P2P applications, thus providing a pioneer study for future massive
deployment campaigns. This particular research item could also
establish cooperation with standardization groups (inside the IETF)
in order to enhance some transitional mechanisms or to develop brand
new solution carefully tweaked for the peculiarities of P2P.
3.3. Analysis of Legacies
A variety of P2P algorithms currently exist that have been shown to
properly operate on the Internet. For many reasons, some P2P
algorithms may not properly operate when ported to IPv6 or vice-
versa.
The analysis of legacies is aimed to discover and resolve (if any)
legacy algorithm dependencies with the underlying transport level.
Moreover, we would provide a pioneer roadmap for porting and
developing P2P applications that will be independent of every IP
version.
In order to provide a clear understanding of legacy / transport
dependencies several legacy examples will be given where these
dependencies exist, and if possible where they do not exist. We do
expect that some P2P infrastructures provide a suitable
virtualization of the transport layer so as to isolate applications
from underlying changes. It will indeed be interesting to categorize
several of the existing P2P systems in this manner.
Caviglione Expires September 13, 2006 [Page 5]
Internet-Draft P2Pv6 Problem Statement March 2006
3.3.1. Implementation Oriented Legacies
Nearly all of the P2P algorithms have been developed on the IPv4
platform. The main foreseen legacy problem is related to how the
software implementation handles L3 addresses. For example, many
client interfaces hardcode IPv4 addresses in 4 byte variables. In
this perspective the migration to IPv6 needs a rewrite, even if
small, of a portion of the software. This resembles in many ways the
now passed “Y2000” software problem.
3.3.2. Algorithm Oriented Legacies
Algorithm Oriented Legacies arise when the P2P algorithm relies on
features in protocols only available for a specific version of the IP
protocol. In addition, such legacies cannot be solved by an
implementation workaround or by software rewriting, the difficulty
being tightly coupled with a specific incarnation of the employed
technologies. For example, one can imagine a P2P routing algorithm
with strong dependencies on the IPv4 address structure because the
P2P infrastructure upon which it is defined did not implement a
suitable virtualization that is independent of the underlying IPv4
transport.
3.4. Augmenting P2P Capabilities Via IPv6 Functionalities
IPv6 offers, as built-in, many features developed for IPv4 as add-
ons. We propose to study how the functionalities (e.g., security and
a unique IPv6 address) of IPv6 can be used by P2P applications in
order to build the next-generation of P2P algorithms and
applications.
3.5. Interoperability Between the P2P Virtual Layer and IPv6
Analyze and solve potential interoperability problems between the
IPv6 layer and the P2P virtualization layer.
3.6. Analogies between IPv6 and P2P Addressing Schemes
IPv6 offers along with its larger address scheme a rich set of
addressing modes and configuration techniques, ranging from self-
configuration to DHCP driven configuration procedures. From this
perspective, this portion of the research will investigate how to
create a P2P addressing scheme based on the IPv6 analogies and
discover which, if any, synergies between the two schemes are
exploitable.
Caviglione Expires September 13, 2006 [Page 6]
Internet-Draft P2Pv6 Problem Statement March 2006
4. Subgroup Milestones
Different milestones are envisaged in order to bootstrap further
research and provide solid foundations for future standardization
activities. Milestones conform to the Research Roadmap. Moreover,
each milestone is intended as an input for the overall IETF – IRTF
world, trying to explain behaviors of P2P from different points of
view.
In more detail:
o Problem statement draft about P2P over v4: How problems are solved
with IPv4 (e.g., rendezvous nodes, relaying nodes, push
messages...) and how at least some of these problems can be
avoided using IPv6.
o "Reverse" problem statement draft: How the transition mechanism
could endanger the use of P2P applications by adding complexity to
the algorithms in order to cope with the presence of such
mechanisms.
o P2P on IPv6 Best Common Practices: How the use of IPv6 could
either add functionalities to the actual P2P technology pool, or
simply permit the same functionalities but by the means of less
complicated algorithms.
o Problem statement draft about P2P applications and IPv4
dependencies: Investigation of P2P technologies already
standardized by the IETF or under discussion (e.g., MIKEY,
P2PSIP).
o P2P and IPv6 addressing synergies and analogies.
o A final document explaining the requirements for P2P applications
and their associated network deployment in order to have a working
and convenient P2P system for IPv6 applications.
4.1. Additional Considerations on Milestones
Milestones are not solely introduced as checkpoints or goals to sync
and evaluate the subgroup’s outcome. Milestones are also intended to
provide help to WG’s that might be engaged in studying P2P networking
jointly with other IETF technologies. For instance, a contribution of
the P2Pv6 subgroup might avoid another subgroup investigating low-
level requirements when developing new solutions (e.g., the P2PSIP
working group).
Caviglione Expires September 13, 2006 [Page 7]
Internet-Draft P2Pv6 Problem Statement March 2006
5. Intermediate Outcomes
While preparing this document, some preliminary discussions about the
joint use of P2P and IPv6 have taken place. In one instance, a
discussion about the use of mobile features of IPv6 and P2P has been
done. Moreover, this discussion conforms to the Research Roadmap and
is will be reported.
5.1. Persistent Infrastructure features inherited from IPv4
When deploying P2P in a fully compliant IPv6 infrastructure, some
strategies used with IPv4 will persist. For example, in spite of the
adoption of IPv6 the use of NAT-like boxes to hide real networks can
be expected to continue.
In this vein, if there is the need to contact a peer (e.g., a home
gateway or set top box), and a NAT/firewall is in place, then end-to-
end connection problems will arise. One simple solution is a super-
peer network in the open Internet that proxies connections and
provides store and forward capabilities for the peers it hosts.
Hence, in a complex IPv6 deployment, a mixture of the two approaches,
i. e., thep2p layer along with NAT traversal protocols, will require
investigation.
5.1.1 Strengths of IPv6 and end-to-end transparency
Even if not strictly related to the P2Pv6 subgroup, an important
analysis about NAT traversal techniques has been discussed in the
IRTF P2P RG[2]. Many P2P applications have some countermeasures
(e.g., ad-hoc algorithms or signaling mechanisms) to exploit
workarounds for the lack of transparency due to the presence of
mediating devices. In this perspective, two major considerations can
be made:
o In a full IPv6 deployment NAT/firewall devices will continue
protect or isolate portions of local area networks. Hence,
evaluating traversal techniques exploited by the P2P layer is
mandatory to understand if they can be ported from IPv4 to IPv6.
o Many “low-level” techniques, such as the UDP hole punching have
been proven to be effective as a means to by-pass the lack of
transparency introduced by NAT devices [2]. Thus, the restoration
of end-to-end transparency should not be the only “technology
driver” for the adoption of IPv6 as the underlying technology for
P2P systems.
Caviglione Expires September 13, 2006 [Page 8]
Internet-Draft P2Pv6 Problem Statement March 2006
6. Related Work
A variety of discussions about the use of P2P and IPv6 have been
completed. The idea of mixing the “best of the two worlds” is
something that has been discussed and proposed in different
Industrial talks and Academic works. In addition, blending IPv6 with
P2P has been explicitly taken into account in the Recommendation
Document prepared by the Italian IPv6 Task Force [3].
In [4] an IPv6 based Node Discovery Stack (NDS) is proposed in order
to make the usage of personal P2P application possible. The work
clarifies the architecture under the Personal Inter-Network (PIN)
framework and shows how the NDS could enhance the personal
communication among cooperating devices. In the context of IPv6
enabled devices, [5] proposes a network monitoring system for a
variety of devices ready to provide their services via a network
using a hybrid P2P architecture. The P2P architectural flavor has
been selected to achieve scalability and a loose coupling of
networked entities.
Being more focused on exploiting peculiar techniques, [6] proposes to
implement an IPv6 routing infrastructure as a self-organizing overlay
network on top of the current IPv4 infrastructure. The work
highlights how different entities can be constructed to tunnel
through NAT’s and firewalls, as well as how to improve the robustness
of the routing infrastructure and to provide efficient and resilient
implementations for features such as multicast, anycast, and mobile
IP using currently available P2P protocols.
Regarding commercial services, [7] fully investigates a ”Durable
Storage” system based on P2P principles that is able to operate over
IPv4 and IPv6. Put briefly, the work describes a commercial service
that will use distributed resources, such as storage and bandwidth,
in a cooperative effort. The “Durable” adjective has been selected so
as to emphasize that the framework is able to guarantee the existence
of the data it contains in "any circumstance" at "any time".
Moreover, the proposed solution is not only IPv6 compatible, but it
could clearly benefit from an IPv6 only version.
7. Liaisons
We plan to put in place explicit liaisons with the IPv6 Task Force
(e.g., creating a bi-monthly “digest” of this project’s efforts to be
sent to the task force leaders). In addition, many IETF WG’s are now
engaged with the porting of preexistent IETF technologies on a P2P
based framework. For instance, the P2PSIP (Peer-to-Peer Session
Initiation Protocol)[8] is studying new architectural blueprints and
Caviglione Expires September 13, 2006 [Page 9]
Internet-Draft P2Pv6 Problem Statement March 2006
services based on the SIP protocol. The efforts undertaken by the two
groups could be considered somewhat overlapping, for instance
concerning the analysis of Legacies, and can profit from a liaison to
prevent reinventing the proverbial wheel.
8. Security Considerations
This document does not raise any new security considerations.
Caviglione Expires September 13, 2006 [Page 10]
Internet-Draft P2Pv6 Problem Statement March 2006
APPENDIX A: Original P2Pv6 Manifest
P2Pv6 (P2PRG-IRTF Activity) B. Yeager and L. Caviglione
Motivation and Scope
IPv6 (Internet Protocol version 6) offers some interesting
differences with respect to IPv4. On one hand it restores end-to-end
transparency, while on the other, it offers many features that are
implemented in IPv4 as add-ons. With such a foundation, IPv6 appears
as an ideal playground for developing Peer-to-Peer (P2P) applications
that rely by design on the interaction between end nodes.
We propose to study the joint use of the P2P paradigm and IPv6 in
order to:
o Show how the IPv6 protocol can provide an excellent environment
for P2P-based applications with the further goal of yielding a
"killer-application" to support the deployment of IPv6.
o Study if the transitional mechanisms developed for managing the
transition and coexistence of IPv4/IPv6 are critical for P2P
applications, thus providing a pioneer study for future massive
deployment campaigns.
o Discover and solve (if any) algorithm legacies and dependencies
with the peculiar network level and provide a pioneer roadmap to
port and develop P2P applications that will be suitable to work on
every IP version.
o Study how the functionalities (e.g., security) of IPv6 can be used
by P2P applications in order to build the next-generation of P2P
algorithms and applications.
o Analyze and solve potential interoperability problems between the
IPv6 layer and the virtualization layer provided by the P2P layer.
o Investigate how to create a P2P addressing scheme based on the
IPv6 analogies and discover if any synergies between the two
schemes are exploitable.
Possible Milestones
Caviglione Expires September 13, 2006 [Page 11]
Internet-Draft P2Pv6 Problem Statement March 2006
Different milestones are envisaged in order to bootstrap further
research and provide solid foundations for future standardization
activities. In more detail:
o Problem statement draft about P2P over v4: How problems are solved
with IPv4 (e.g., rendezvous nodes, relaying nodes, push
messages...) and how at least some of these problems can be
avoided using IPv6.
o "Reverse" problem statement draft: How the transition mechanism
could endanger the use of P2P applications by adding complexity to
the algorithms in order to cope with the presence of such
mechanisms.
o P2P on IPv6 Best Common Practices: How the use of IPv6 could
either add functionalities to the actual P2P technology pool, or
simply permit the same functionalities but via less complex
algorithms.
o Problem statement draft about P2P applications and IPv4
dependencies: Investigation of P2P technologies already
standardized by the IETF or under discussion (e.g., MIKEY,
P2PSIP).
o P2P and IPv6 addressing synergies and analogies.
o A final document explaining requirements for P2P applications and
their associated network deployment in order to have a working and
convenient P2P over IPv6 applications.
Liaisons
Put in place explicit liaisons with the IPv6 Task Force (e.g.,
creating a bi-monthly "digest" of this project's efforts to be sent
to the task forces leaders).
Caviglione Expires September 13, 2006 [Page 12]
Internet-Draft P2Pv6 Problem Statement March 2006
9. References
9.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
9.2. Informative References
[2] S. Guha, P. Francis, “Characterization and Measurement of TCP
Traversal through NATs and Firewalls", IMC 2005. Available on-
line at: http://nutss.net/pub/imc05-tcpnat.pdf
[3] L. Ferracci (ed.), M. Morelli (ed.), E. Albertin, F. Capuzzo,
P. Casagranda, L. Caviglione, M. D’Itri, M. R. Spada, “IPv6
Task Force Italiana - Raccomandazione Finale”, only in Italian,
available on-line at:
http://www.it.ipv6tf.org/minutes/RaccomandazioneFinale.pdf
[4] F. Lin, C. Chen, H.-C. Chao, W.-M. Chen, “Personal
Internetworking Using P2P Architecture over IPv6”, Proceedings
of the 9th International Symposium on Consumer Electronics
(ISCE),June 2005, pp. 14-19.
[5] K. Kubo, J. Murakami, T. Hoshi, T. Yokogawa, “Hybrid Peer-to-
Peer System for Network Monitoring of Field Devices”, SICE 2003
Annual Conference, August 2003, pp. 2818-2823.
[6] L. Zhou, R. van Renesse, M. Marsh, “Implementing IPv6 as a
Peer-to-Peer Overlay Network”, Proceedings of the 21st IEEE
Symposium on Reliable Distributed Systems, October 2002, pp.
347-351.
[7] E. Jacob, J.J. Unzilla, M.V. Higuero, P. Saiz, M. Aguado, C.
Pinedo,”A dual (IPv4/IPv6) <<Durable Storage>>" Commercial
Service”, Proceedings of 9th International Conference on
Advanced Information Networking and Applications (AINA), March
2005, Vol. 2, pp. 856-861.
[8] P2PSIP Mailing List,
https://lists.cs.columbia.edu/pipermail/p2p-sip/
Caviglione Expires September 13, 2006 [Page 13]
Internet-Draft P2Pv6 Problem Statement March 2006
Authors' Addresses
Luca Caviglione
CNIT
University of Genoa Research Unit
Via Opera Pia 13
16145 Genoa, Italy
Email: luca.caviglione@cnit.it
William Yeager
Peerouette, Inc.
Menlo Park
U.S.A., CA.
Email: Bill@Peerouette.com
Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org
Disclaimer of Validity
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
Caviglione Expires September 13, 2006 [Page 14]
Internet-Draft P2Pv6 Problem Statement March 2006
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement
Copyright (C) The Internet Society (2006).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
Acknowledgment
Funding for the RFC Editor function is currently provided by the
Internet Society.
Caviglione Expires September 13, 2006 [Page 15]