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P2PRG                                                           S. Kamei
Internet-Draft                                           NTT Corporation
Intended status: Informational                                 T. Momose
Expires: November 21, 2010                                 Cisco Systems
                                                                T. Inoue
                                                            T. Nishitani
                                                      NTT Communications
                                                            May 20, 2010


 ALTO-Like Activities and Experiments in P2P Network Experiment Council
                  draft-kamei-p2p-experiments-japan-03

Abstract

   This document provides some suggestions about ALTO architecture
   through experiments made by P2P Network Experiment Council in Japan.
   This document also introduces experiments made by the Council in
   Japan to harmonize P2P technology with the infrastructure.
   Specifically, this document describes Hint Server technology, which
   is similar to ALTO technology.

Status of this Memo

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Copyright Notice

   Copyright (c) 2010 IETF Trust and the persons identified as the



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   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Background in Japan  . . . . . . . . . . . . . . . . . . . . .  3
     2.1.  P2P traffic  . . . . . . . . . . . . . . . . . . . . . . .  3
     2.2.  Impact on network infrastructure . . . . . . . . . . . . .  4
   3.  The object of P2P Network Experiment Council . . . . . . . . .  5
   4.  Activity in P2P Network Experiment Council . . . . . . . . . .  6
     4.1.  Dummy Node . . . . . . . . . . . . . . . . . . . . . . . .  6
     4.2.  Hint Server ('08)  . . . . . . . . . . . . . . . . . . . .  6
     4.3.  Difference between P4P and Hint Server technology  . . . . 10
     4.4.  Difference between ALTO and Hint Server technology . . . . 12
   5.  High-Level Trial Results . . . . . . . . . . . . . . . . . . . 12
     5.1.  Peer Selection with P2P  . . . . . . . . . . . . . . . . . 13
     5.2.  Peer Selection with the Hint Server  . . . . . . . . . . . 13
   6.  Next steps . . . . . . . . . . . . . . . . . . . . . . . . . . 13
   7.  Feedback to ALTO WG  . . . . . . . . . . . . . . . . . . . . . 14
     7.1.  Harmonizing a Hint Server with ALTO  . . . . . . . . . . . 14
     7.2.  Measurement mechanism  . . . . . . . . . . . . . . . . . . 15
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 15
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 15
   10. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 15
   11. Informative References . . . . . . . . . . . . . . . . . . . . 15
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16














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1.  Introduction

   An overlay network, which is used by P2P and other applications,
   offers the advantage of allowing flexible provision of services while
   hiding the lower layer network.  The downside is that inefficient
   routes are often taken in the lower IP network, thereby increasing
   the network load.  Several proposals have been made to build an
   overlay network that takes account of the information about the lower
   layer network.  Since the management of the Internet is highly
   distributed, it is difficult to implement such proposals and thus
   optimize a network without the cooperation of network providers.

   Recently, the controversy between the overlay network and the network
   providers have been rekindled.  Under these circumstances, some
   researchers have studied overlay network control technology that
   takes account of the network topology information obtained from
   network providers.

   One of activities concerning this issue has been made by the P2P
   Network Experiment Council in Japan.  This document reports on the
   issues addressed and experiments being made by the P2P Network
   Experiment Council in Japan, focusing on the experiments made from
   2007 to 2008.


2.  Background in Japan

2.1.  P2P traffic

   In Japan, the major of P2P applications used today is Winny.  P2P
   applications are the sources of a considerable volume of traffic.
   Recent study [1] showed more than 60% of Internet traffic in Japan is
   generated by P2P applications.

   Although traffic from P2P applications increased much more rapidly
   than traffic from client-server-type web applications, it has leveled
   off lately as a result of legal restrictions advocated by copyright
   management organizations and traffic control implemented by ISPs.
   According to [2], video delivery sites using Flash has again
   increased volume of web traffic per user, making P2P traffic
   relatively less conspicuous than before.

   Consequently, some believe that P2P traffic is no longer a threat to
   the infrastructure.  P2P applications, however, rapidly became widely
   used to get around the limit of the servers' capacity, which was
   caused by the increase in demand for delivery of music files.  It is
   likely that the traffic of client-server video delivery will shift to
   P2P delivery.



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   In fact, some P2P content delivery systems solve copyright issues,
   for example, Sharecast, Ocean-Grid, TVBand, and so on.  The
   transmission of President Obama's Inaugural Address, which is the
   largest-scale transmission of content in recent history, was mostly
   of the client-server type.  However, the delivery by CNN used a P2P
   plug-in made by Octoshape.  Traffic data observed by Illinois
   University revealed unique traffic patterns that the upstream traffic
   exceeded the downstream traffic.

2.2.  Impact on network infrastructure

   One of advantage of using P2P technology for content delivery is that
   peers exchange content directly among themselves.  This reduces the
   physical load on servers .  Also, P2P applications can reduce
   upstream traffic from an original content server.  This is
   significant that the charge for upstream traffic is usually traffic-
   sensitive for content delivery services, and it is not negligible.

   Actually, the volume of traffic sent by the content server in
   TVBank's P2P content delivery was reduced by a maximum of 96%
   compared with the volume of traffic received by users [3].  This
   indicates the great cost-saving of P2P technology from the
   perspectives of the load on server hardware and the traffic relaying
   cost of data centers.  However, the story is quite different for
   network providers.  From viewpoint of network providers, the traffic
   that content servers generate has shifted to the edge network and the
   amount of traffic has not necessarily been reduced.  Another problem
   for network providers that an extremely inefficient routing may be
   selected has been raised.  It is because overlay network systems are
   configured without any regard to the structure of the lower layer
   network or network geometry.

   Traffic on the Internet used to be limited by the capacity of
   servers.  Today the improvement in the scalability of servers has
   made it likely that network resources will be used up before server
   resources are.  Using P2P applications increases the volume of
   traffic per user remarkably.

   Faced with increase in the load on network infrastructure, network
   providers are compelled to take actions to overcome the sudden
   increase in facilities' cost.  Representative actions include placing
   content in IXs or data centers, introducing bandwidth control, and
   raising the access fees [2].

   In the future, video posting sites, which has been delivered using
   client-server applications, may adopt P2P system.  The increase in
   traffic arising from such a shift will be a great threat to the
   network.



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3.  The object of P2P Network Experiment Council

   The Japanese Ministry of Internal Affairs and Communications, which
   has jurisdiction over information and communication systems in Japan,
   held meetings of an advisory panel on network neutrality from 2006 to
   2007 in order to study issues related to next generation networks,
   such as how to ensure fairness in the use of networks and how to
   define fairness in cost burden.  The panel took an interest in P2P
   technology as a solution to the impending traffic saturation in the
   backbone network resulting from the rapid expansion of broadband
   access in Japan, and formed a "Working Group on the P2P Network",
   which carried out an intensive study of P2P networks.

   The Working Group reported that it is necessary to undertake the
   following four activities, which are intended to encourage the
   government to adopt relevant policies [4]:

   o  Formulate guidelines to be self-imposed by the industry on P2P
      file delivery applications,

   o  Promote feasibility tests of P2P networks,

   o  Study the current state of traffic control and promote the sharing
      of information,

   o  Hold working group meetings on traffic control.

   The first two proposals led to the establishment of the P2P Network
   Experiment Council supported by the Japanese Ministry of Internal
   Affairs and Communications [5].  The Council, with membership from
   P2P delivery providers, content holders, and network providers, began
   a variety of delivery experiments, which were expected to strengthen
   cooperative control between different layers.  In contrast to P4P,
   which takes a relatively top-down approach of adopting architecture
   based on a proposal from a university, the Council is characterized
   by its bottom-up approach.  The aim of establishing the Council has
   been described as follows.

      The rapid growth of broadband access enables content delivery
      system to deliver high-quality and high-volume videos securely and
      efficiently.  Although P2P technology is an effective technology
      for this requirement, it still has some issues to be coped with.
      Therefore, the "P2P Network Experiment Council" was established
      with the support of the Japanese Ministry of Internal Affairs and
      Communications with its secretariat set up within the Foundation
      for MultiMedia Communications (FMMC) in order to formulate
      guidelines for providers and conduct feasibility tests so that
      users can receive video delivery services safely.



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   The activities of the P2P Network Experiment Council can be
   classified into two categories.  The first is activities to formulate
   guidelines for the promotion of the commercial use of P2P technology.
   These will enable users to use P2P technology safely, and providers
   to have clear rules they must observe.  The other is feasibility
   tests of P2P technology.  The next section mainly reports on
   experiments conducted from 2007 to 2008.


4.  Activity in P2P Network Experiment Council

4.1.  Dummy Node

   While the effect of delivery using P2P technology on reducing the
   traffic and the load on servers is well known, traffic behavior in
   the Internet is not known.  However, it is not realistic to measure
   the behavior of P2P applications at user terminals connected to the
   Internet because that would require a large-scale arrangement for
   measurement, such as using Deep Packet Inspection (DPI) on aggregated
   lines.  To solve this problem, dummy nodes have been introduced.
   Dummy nodes have been settled in the Internet and P2P applications
   have been installed on these nodes.  Dummy nodes enable us to measure
   and analyze communication among peers.

   Specifically, Linux servers were installed at 40 sites of some ISPs,
   and a virtual Windows environment was installed on the servers.  P2P
   applications which were target to measure were running on that
   environment, and packets were captured by a Linux program to obtain
   information on communication destinations and communication
   frequencies.

4.2.  Hint Server ('08)

   In Japan, bottleneck in IP networks will shift from access networks
   to backbone networks and equipments, such as bandwidth between ISPs
   and capacity in IXs, since FTTH has rapidly spread all over Japan.
   Under this situation. the Council proposed a less restrictive and
   more flexible cooperation between ISPs than ALTO.  The proposed
   method consists of the following elements: (1) P2P clients, (2) P2P
   control servers, and (3) a peer selection hint server, and a Hint
   Server. (1) and (2) are existing systems but whether (2) exists
   depends on each application. (3) is a server that provides a hint as
   to the selection of a peer, and plays a role equivalent to that of
   iTracker in P4P's study.  Note that this proposal was based on
   results of experiments using dummy nodes.  The results showed that it
   was possible to reduce unnecessary traffic that flows across the
   boundaries of districts or ISPs through providing information about
   the physical network to P2P applications.



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   When a peer joins the network, it registers its location information
   (IP address) and supplementary information (line speed, etc.) with
   the Hint Server.  The Hint Server makes a mapping of the new peer
   (P2P client) based on network topology information obtained from the
   ISP, generates a routing table in which peers are listed in the order
   of priority for selection, and returns the table to the peer.

   If all information can be made public, the above procedure can
   produce a result which is close to overall optimization.  However,
   some information held by ISPs can often be confidential.  Besides, in
   some cases, the volume of calculation required to process all
   information can be excessive.  To avoid these problems, it is planned
   to conduct experiments with a limited set of functions, analyze
   experiment results, and gradually expand the scope of optimization.

   A control mechanism that makes use of all possible information is
   difficult not only technically but also because it is difficult to
   achieve coordination among providers.  In consideration of these
   difficulties, the P2P Network Experiment Council has been limiting
   the implementation and experiments to the following scope since 2006.

   Figure 1 shows an outline of the hint server.


   +---------+   GetLocation    +-------------GeoIP DB Server---------+
   |         |  +-----------+   |   +----------+      +-----------+   |
   |         |--|IP Address |-->|   | GeoIP DB |      |Quagga etc |   |
   |         |  +-----------+   |   +----------+      +-----------+   |
   |         |                  | +-------------+  +----------------+ |
   |         |  +-----------+   | |  District   |  |    Routing     | |
   |         |--|AS Code:   |---| | information |  |information(DGP)| |
   |         |  |Regional   |   | |             |  |                | |
   |P2P Peers|  |Information|   | |   Range of  |  |AS Code(origin) | |
   |   or    |  +-----------+   | | IP address  |  |                | |
   | Contro| |                  | +-------------+  +----------------+ |
   | Server  |                  +-------------------------------------+
   |         |                                  |      ^
   |         |  PeerSelection                   v      |
   |         |  +-----------+   +--------------------------------------+
   |         |--|IP Address |-->| +--Prioryty Node Selection System--+ |
   |         |  |    List   |   | |                                  | |
   |         |  +-----------+   | |     Peer candidate ranking       | |
   |         |  +-----------+   | |                                  | |
   |         |--|  Ranking  |-->| +----------------------------------+ |
   |         |  +-----------+   +--------------------------------------+
   +---------+

                                 Figure 1



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   The network information used by the Hint Server is not information
   solicited from individual ISPs but the AS number and district
   information, which are more or less already public.  Routing tables
   are not generated.  Instead, peers within the same ISP or the same
   district are selected with higher priority in order to confine
   traffic to within the same ISP or the same district.

   When the Hint Server receives an IP address, it returns its attribute
   information, to achieve the above.  A peer can select a peer based on
   the returned information.  This operation is called GetLocation.
   However, in preparation for the time when it becomes necessary to
   hide topology information, an interface is provided through which a
   priority order is returned in response to an input of a list of
   candidate peers.  This operation is called PeerSelection.

   Although the priority node is selected based on the criterion that it
   is within the same ISP or the same district, this type of selection
   is not very effective if the number of participating peers is small.
   Table 1 shows ratio of peers within the same AS or the same
   prefecture calculated from the distribution of ASs and prefectures in
   the IP address space from one-day data on a Winny network.

                      +--------------------+--------+
                      | Conditions         |  ratio |
                      +--------------------+--------+
                      | AS matches         |  6.70% |
                      | Prefecture matches | 12.76% |
                      | Both match         |  2.09% |
                      | Neither match      | 78.45% |
                      +--------------------+--------+

                 Table 1: AS and prefecture distributions

   Since, in addition to the above, the presence/absence of content
   affects the result, the control of selecting a peer within the same
   district may be inadequate.  Therefore, it is necessary to introduce
   the weight of a continuous quantity that reflects the physical
   distance or the AS path length as an indicator of the proximity of
   the areas involved.

   In consideration of the above, the following two measures are used
   for the evaluation of proximity between peers in a Hint Server.

   o  AS path length (distance between ISPs)

      Distances between peers are weighted using the degree of paths'
      matching from an origin AS to ASs that target peers belong to.
      The degree of paths' matching means ratio of common paths from an



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      origin AS (for example, 4/6 between A-B-C, and A-B-D, 6/8 between
      A-B-C-D and A-B-C-E).  In this year, the OCN is used as an origin
      AS.  Distance is calculated as int((1.0- degree of matching of AS
      paths)*15).  Distance is 15 if either of AS path is indefinite,
      and is 0 if there is a perfect match.

   o  Physical distance

      Distances between peers are measured using physical distance of
      prefectural capitals that target peers belong to.  The distance
      between prefectural capitals is used to calculate physical
      distance.  Distances between prefectural capitals are sorted into
      ascending order, and then into bands, with weights 1 to 15
      assigned to them so that there are a more or less equal number of
      "capital pairs" in each band.  If either of their location is
      indefinite, distance is equal to 15 and, if they are in the same
      prefecture, distance is equal to 0.

      Evaluation of distances between peers showed that the distribution
      of distances was almost uniform when distances between peers are
      normalized.  This result suggests that using normalized distances
      expands the area where the control by a Hint Server is effective.

   An example of the request and the response

   o Request


       POST /PeerSelection HTTP/1.1
       Host: ServerName
       User-Agent: ClientName
       Content-Type: text/plain; charset=utf-8

       v=Version number
       [application=Application identifier]
       ip=IP address of physical interface
       port=Port number of physical interface
       [nat={no|upnp|unknown}]
       [nat_ip=Global IP address using UPnP]
       [nat_port= Global port number using UPnP]
       [trans_id=transcation ID]
       [pt=Flag of port type]
       [ub=upload bandwidth]
       [db=download bandwidth]







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   o Response


      HTTP/1.1 200 OK
      Date: Timestamp
      Content-Type: text/plain; charset=utf-8
      Cache-control: max-age=max age
      Connection: close

      v=Version number
      ttl=ttl
      server=hint server name
      ...
      trans_id=transaction ID
      pt=Flag of port type
      client_ip=Peer IP address observed from server
      client_port=Peer port number observed from server
      numpeers=number of respond peer
      n=[src address] dst address / cost / option

4.3.  Difference between P4P and Hint Server technology

   To explain difference between P4P and Hint Server technology, the
   architecture proposed by P4P is described.  P4P aims to control
   traffic in such a way that traffic is confined within the same
   district or AS.  As shown in Figure 2, iTracker provides an interface
   for P2P content delivery using appTracker and peers in BitTorrent.
   This arrangement provides a framework for efficient control based on
   network information.

   In this framework, it is proposed that ISPs and applications share
   the following types of information through iTracker:

   o  Info: information about peers within an ISP

      - ASID AS number

      - Group number of PID node (peer)

      - LOC: virtual and geographical coordinates

   o  Policy: information about policy on usage specified by an ISP

      - Ratio between outgoing traffic and incoming traffic that flows
      between domains






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      - Desirable daily traffic variation pattern on a link

      - Specifications about relations between peer groups (PID)

   o  Capability: information about the capability of an ISP

      - Information about usable service classes

      - Information about the cache server

   Note that [6] reports on the results of a field test in which it was
   attempted to reduce overall traffic by using the above concept to
   confine traffic exchange destinations to within the same ISP or the
   same city.  It reports that, in an evaluation with a Verizon network,
   traffic to locations outside an ISP was reduced by 30 to 50% and that
   the ratio of inter-city traffic to Verizon's total traffic was more
   or less halved.


                            ISP
                +------------------------+         Internet
                |   +----------------+   |      +------------+
                |   |  iTracker      |   |      | appTracker |
                |   |   *Info        |--------> +------------+
                |   |   *Policy      |   |            ^
                |   |   *capability  |   |            |
                |   +----------------+   |            |
                |                        |            |
                |   +----------------+   |            |
                |   |      Peer      |----------------+
                |   +----------------+   |
                +------------------------+

                                 Figure 2

   Comparing P4P with Hint Server technology, the following three
   differences are observed:

   o  Target of optimization:

      P4P technology focuses on optimization within an ISP, while Hint
      Server technology focuses on optimization in backbone traffic.

   o  Target applications:

      P4P technology focuses on supporting BitTorrent, while Hint Server
      technology does not specify any P2P applications.




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   o  Strength of cooperation between P2P providers and ISPs:

      P4P technology requires close cooperation between ISPs and P2P
      providers, while Hint Server technology does not require.

4.4.  Difference between ALTO and Hint Server technology

   ALTO technology is more general approach than P4P technology.  And
   Hint Server technology has more similar focus of this technology.

   Hint Server offers similar information of ALTO service and can easily
   supports following ALTO Services.

   o  Map Service

      The cost type is computed by physical distance and AS path length,
      and the mode is numerical.

      PID information, it is same as AS and physical location, does not
      offered to client.

   o  Map Filtering Service

   o  Endpoint Cost Service

      Hint Server only offers map information associated with requested
      IP addresses.

   ALTO framework has more generality but the following two points are
   not sufficiently improved or some operational solution should be
   offered.

   o  Target of optimization:

      ALTO technology focuses on optimization within an ISP, while Hint
      Server technology focuses on optimization in backbone traffic.

   o  Strength of cooperation between P2P providers and ISPs:

      ALTO technology requires close cooperation between ISPs and P2P
      providers, while Hint Server technology does not require.


5.  High-Level Trial Results







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5.1.  Peer Selection with P2P

   Table 2 shows the result of the analysis of communication in a node
   of an ISP installed in Tokyo, as an example of measurement results.

   +-----------------------------------------+------------+------------+
   | Conditions                              | Experiment | Experiment |
   |                                         |      1     |      2     |
   +-----------------------------------------+------------+------------+
   | *Peers selected within the same ISP     |     22%    |     29%    |
   | *Peers selected within the same         |     19%    |     23%    |
   | district                                |            |            |
   | *Peers selected within the same         |     5%     |     7%     |
   | district and the same ISP               |            |            |
   +-----------------------------------------+------------+------------+

         Table 2: Percentage of communication within the same ISP

   The table shows that the probability of communication with peers in
   the same ISP is proportional to the number of population and the
   share of the ISP in each district.  The data show that peers were
   selected at random.  Note that the vendor of a P2P application used
   in this experiment explained that the mechanism of selection a peer
   using network information can be implemented.  However, peer
   selection is normally based on past information because users often
   cannot actually perceive the effect of using network information.

5.2.  Peer Selection with the Hint Server

   Since the main objective of this experiment was to verify the
   operations of the Hint Server and P2P applications, the degree to
   which traffic in the network was actually reduced was not evaluated.
   However, the distances between a dummy node and a peer were obtained
   from data on the dummy nodes.  An examination of the distances
   between a dummy node and a peer revealed that mean value of distance
   after the Hint Server was introduced was reduced by 10% and that 95%
   value of that was reduced by 5%.


6.  Next steps

   This document has reported on activities aimed at achieving
   cooperative control between the P2P/overlay network and the network
   infrastructure.  Specifically, it has described issues to be
   addressed and the activities of the P2P Network Experiment Council in
   Japan, which was established to address these issues.  It has also
   introduced the Council's activities, from 2007 to 2008, focusing on
   the use of a Hint Server, which is a feature of the traffic



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   engineering mechanism proposed by the Council.

   The P2P Network Experiment Council has been renamed the Advanced
   Network Use Promotion Council.  The new Council aims to create new
   network services suitable for the broadband environment and to
   promote the widespread use of such services in rural areas.  It has
   expanded its scope of work to include all cache technologies,
   including P2P technology.  It will promote more advanced use of the
   network by encouraging an exchange of views among a broad spectrum of
   parties on how to use the network effectively, and by supporting a
   variety of feasibility tests.

   The Council aims to continue the analysis of the experiment results
   obtained, and further study by involving a wider spectrum of P2P
   providers, network providers and delivery service providers.


7.  Feedback to ALTO WG

   This section describes what the authors learned with this experiment
   would be useful for the ALTO WG.

7.1.  Harmonizing a Hint Server with ALTO

   As described before, a Hint Server control mechanism focuses on
   control between ISPs, while ALTO does control within an ISP.
   Generally speaking, control mechanism that a peer chooses a replica
   from its neighbors shows higher performance when probability of a
   peer having a content is higher.  This means ISP cooperation
   mechanism that enlarges area in choosing peers will have much impact
   on P2P performance.  The authors consider combination of these two
   mechanisms produce better P2P performance.  The authors propose
   hierarchical structure to harmonize a Hint Server with ALTO.  From
   viewpoint of cooperation between ISPs, fine information is not
   necessarily required and it is difficult to exchange fine information
   between ISPs.  Considering this situation, the authors use only
   coarse information to control backbone traffic in the experiments
   this year, though demand of controlling traffic within an ISP using
   fine information will arise in the near future.  The authors consider
   that introducing hierarchical structure into ALTO is necessary to
   cope with both situations.  Actually, the authors plan to try a
   hierarchical control mechanism in the next steps, which include the
   following two steps.

   o  In the first step, coarse information about whole the network is
      used to select ISPs.





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   o  Next, fine information within the ISP is used to select a peer.

7.2.  Measurement mechanism

   In experiments, there were two difficulties as follows:

   o  Evaluating effect of introducing a Hint Server was difficult,
      since P2P applications had their own measurement mechanisms.

   o  How to treat priority orders of peers suggested by a Hint Server
      could not be predetermined for P2P applications.

   From these experiences, the authors consider that clarifying
   requirements about measurement mechanisms for P2P applications are
   necessary also in Alto.


8.  Security Considerations

   There are no security considerations in this document.


9.  IANA Considerations

   No need to describe any request regarding number assignment.


10.  Acknowledgments

   These experiments were performed under cooperation among P2P Network
   Experiment Council members, and DREAMBOAT co.,ltd., Bitmedia Inc.,
   Utagoe.  Inc. and Toyama IX have especially supported analyses of the
   experimernts.  The authors appreciate Tohru Asami, Hiroshi Esaki and
   Tatsuya Yamshita for their constructive comments.


11.  Informative References

   [1]  Hiroshi Esaki, "The State of Traffic and the Effects of P2P",
        Special Symposium on Broadband, September 2008 (in Japanese).

   [2]  Yoichi Yamazaki, "ISPs have Begun to Explore Tomorrow due to the
        Expansion of Traffic", Nikkei Communications, December 2007 (in
        Japanese).

   [3]  TVBank, "Live Delivery using `BB Broadcast'Achieving 96% Saving
        in Traffic!", http:.wwww.tv-bank.com/jp/20081031.html, 2008 (in
        Japanese).



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   [4]  Ministry of Internal Affairs and Communications, "Disclosure of
        the Report `Working Group on P2P Networks'",
        http://www.soumu.go.jp/menu_news/s-news/2007/070629_11.html,
        2007 (in Japanese).

   [5]  The Foundation for MultiMedia Communications, "The P2P Network
        Experiment Council", http://www.fmmc.or.jp/P2P/about.htm, 2007
        (in Japanese).

   [6]  Open P4P, "P4P Field Tests: Yale-Pando-Verizon",
        http://www.openp4p.net/front/fieldests, 2009.


Authors' Addresses

   Satoshi Kamei
   NTT Service Integration Laboratories
   3-9-11, Midori-cho
   Musashino-shi, Tokyo  180-8585
   JP

   Phone: +81-422-59-6942
   Email: kamei.satoshi@lab.ntt.co.jp


   Tsuyoshi Momose
   Cisco Systems G.K.
   2-1-1 Nishi-Shinjuku
   Shinjuku-ku, Tokyo  163-0409
   JP

   Phone: +81-3-5324-4154
   Email: tmomose@cisco.com


   Takeshi Inoue
   NTT Communications
   3-4-1, Shibaura
   Minato-ku, Tokyo  108-8118
   JP

   Phone: +81-3-6733-7177
   Email: inoue@jp.ntt.net








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   Tomohiro Nishitani
   NTT Communications
   1-2-20, Shibaura
   Minato-ku, Tokyo  108-8118
   JP

   Phone: +81-50-3812-4742
   Email: tomohiro.nishitani@ntt.com











































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