P2PRG                                                           S. Kamei
Internet-Draft                                        NTT Communications
Intended status: Informational                                 T. Momose
Expires: April 18, 2013                                    Cisco Systems
                                                                T. Inoue
                                                            T. Nishitani
                                                      NTT Communications
                                                        October 15, 2012

 ALTO-Like Activities and Experiments in P2P Network Experiment Council


   This document introduces experiments to clarify how ALTO-like
   approach was effective to reduce network traffic made by a Council in
   Japan to harmonize P2P technology with the infrastructure.  And this
   also provides some suggestions that might be useful for ALTO
   architecture learned through our experiments.  Especially, experiment
   for application independent ALTO-like server operation.

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   This Internet-Draft will expire on April 18, 2013.

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   carefully, as they describe your rights and restrictions with respect
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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
     2.3.  The object of P2P Network Experiment Council . . . . . . .  5
   3.  The object of P2P Network Experiment Council . . . . . . . . .  5
   4.  The details of the experiments . . . . . . . . . . . . . . . .  7
     4.1.  Dummy Node . . . . . . . . . . . . . . . . . . . . . . . .  7
   5.  Hint Server ('08)  . . . . . . . . . . . . . . . . . . . . . .  8
   6.  High-Level Trial Results . . . . . . . . . . . . . . . . . . . 13
     6.1.  Peer Selection with P2P  . . . . . . . . . . . . . . . . . 13
     6.2.  Peer Selection with the Hint Server  . . . . . . . . . . . 13
   7.  Considerations . . . . . . . . . . . . . . . . . . . . . . . . 14
     7.1.  Next steps . . . . . . . . . . . . . . . . . . . . . . . . 14
     7.2.  Feedback to ALTO WG  . . . . . . . . . . . . . . . . . . . 15
       7.2.1.  Hierarchical architecture for ALTO servers . . . . . . 15
       7.2.2.  Measurement mechanism  . . . . . . . . . . . . . . . . 15
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 16
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 16
   10. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 16
   11. Informative References . . . . . . . . . . . . . . . . . . . . 16
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17

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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. [1] [2] 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 about network resource wastefulness has 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 the activities concerning this issue has been made by the P2P
   Network Experiment Council in Japan.  We planned some experiments in
   the council.  This document reports on the issues addressed and
   experiments being made by the council.

   This experiment made from 2007 to 2008, because P2P traffic had
   reduced due to rivision of copyright law in Japan.  And recently,
   dominant traffic is HTTP based flash streaming in Japan, U.S, and so
   on.  However, P2P traffic remains in large traffic, like PPStreaming,
   in Asia (except Japan)[3], and P2P technology is very userful in such
   a realtime streaming area.

   Our experience in this experiment might be useful for ALTO
   architecture, especially for application independent and multi
   application ALTO-like server operations.  We suggest that generic
   measurement mechanism is important because each application has
   different mechanism and it is difficult to compare the effectiveness.

   This document is a product of the P2P RG.  The views in this document
   were considered controversial by the P2P RG but the RG reached a
   consensus that the document should still be published.

2.  Background in Japan

2.1.  P2P traffic

   As of 2008, the world most popular P2P file sharing application,
   Bittorrent, isn't widely deployed in Japan.  Instead, other Japan
   specific file sharing P2P applications such as Winny [4], Share [5],

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   and so on, still occupy 40% of the Internet traffic in Japan even
   though many those P2P users were arrested for sharing illegal files
   with these P2P apps.

   Each P2P file sharing application has a unique protocol and none of
   them have a large market share therefore making it hard to
   effectively control.

2.2.  Impact on network infrastructure

   One of the advantage of using P2P technology for content delivery is
   that peers exchange content directly among themselves without server
   bottleneck.  This reduces the load on servers.  Also, P2P
   applications can reduce upstream traffic from an origin content
   server.  This reduce server cost dramatically.

   It is also known that server cost could be reduced with P2P
   technology.  However, the story is quite different for network
   providers.  From the 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 with using P2P
   technology for reducing server cost.  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.

   In some cases, the total amount of traffic on the Internet used to be
   limited by the capacity of servers.  For those cases, P2P technology
   can improve the scalability of servers , however it may exhaust
   network resources.  Moreover, 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 internet exchanges or data centers, introducing bandwidth
   control, and raising the access fees [6].

   However, current dominant traffic is HTTP based flash streaming in
   Japan, U.S, and so on.  However, P2P traffic remains in large
   traffic, like PPStreaming, in Asia (except Japan)[3], and P2P
   technology is very userful in such a realtime streaming area.  The
   increase in traffic arising from such a shift may be a great threat
   to the network.

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2.3.  The object of P2P Network Experiment Council

   In order to reduce Internet traffic and encourage legitimate use of
   P2P technologies, the Japanese government led to establish a new
   council called P2P Network Experiment Council conjunction with
   commercial P2P application vendors and ISPs in 2006.

   Then the council had started to develop regulations that include
   several guidelines such like an advance notice to restrict bandwidth
   to heavy traffic users.  In accordance with the regulations, some
   ISPs introduced solutions that reduce traffic caused by P2P file
   sharing applications.

   Besides this activity, the council also looked for new ways to
   control traffic by commercial P2P applications with ISPs, carriers,
   contents providers and P2P system vendors.  In this work, the council
   had experiments that introduced ALTO-like system and observed how the
   traffic was reduced by redirecting to proper peers on the real
   Internet in Japan.

   In our experiment, the council deployed hint servers, which are
   described in section 4.  Hint servers have a protocol offering
   network distance to peers, which is disclosed to P2P application

   Using hint server, P2P application vendors can introduce ALTO
   concepts easily to their P2P distribution systems.  Because the
   protocol provided of hint servers is independent on specific P2P
   application vendors like Bittorrent, the council defines the protocol
   to be able to use any P2P application vendors.  It needs to gather
   network information from ISPs to offer network distance to peers,
   however many ISPs dislike to disclose such information to others.
   Therefore, hint servers are designed to offer little information
   about ISPs' network architecture to P2P application vendors.

   To monitor traffic of peers, the council also deployed dummy node,
   which are described in section 3.1.

   This memo describes the overview of the experiments.

3.  The object of P2P Network Experiment Council

   Ministry of Internal Affairs and Communications Japan, 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

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   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 [7]:

   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 Ministry of Internal Affairs and
   Communications Japan [8].  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.

   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 describes mainly

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   experiments conducted from 2007 to 2008.

4.  The details of the experiments

   The council has already learned that the server cost could be reduced
   with using P2P technology for contents delivering by investigating
   data offered by the members of the council.  For example, the data
   brought by the vendors shows as follows:

      90% of traffic was reduced with UG Live by Utagoe Inc [9].

      The costs of delivering to tens of thousand subscribers was
      reduced to 1/5 with BBbroadcast with TV Bank Corp. [10]

   On the other hand, these reduced server costs may affect network
   load.  One of the goals of our experiments was to visualize the
   impacts and propose an architecture to reduce network load caused by
   these new technologies.

   In order to visualize the reduction of network cost, we had to
   modelize P2P applications and multi-ISP environment.  It will also
   needed for visualizing the effectiveness of ALTO-like approach.

4.1.  Dummy Node

   As mentioned before, while the effect of delivery using P2P
   technology on reducing the traffic and the load on servers is well
   known, traffic behavior in the inter-ISP is not known.  In Japan,
   there is a backbone traffic report cooperated with ISPs and IXes
   [11].  However, this measurement requires to capture packets on
   subscribers line to know end user's activity.  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 these problems, we put several nodes called 'dummy nodes' in
   the ISP's networks.  The dummy nodes emulate an end user's PC and P2P
   applications are running on the nodes.  Every P2P node provided by
   participating vendors in the experiment was configured so it always
   contacted the hint server.

   By introducing dummy nodes, we can observe and evaluate how much P2P
   applications have affected networks by measuring the traffic on dummy
   nodes.  Since this method can't measure every subscriber's traffic,
   the accuracy would be less than other methods.  But this make it
   possible to adapt to situations many different P2P applications

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   coexist on a network.  We can say this is suitable for these

   A dummy node consists of Intel PC server, Linux(CentOS), VMWare and
   Windows XP works on VMWare.  With this configuration, all packets can
   be captured without any impacts to the network, nodes and application
   behaviors.  And it enable us to use different P2P applications for
   windows and evaluate them generally.

   To see behaviors of the node, incoming and outgoing packets are
   captured on Linux because every packets are transmitted through it.
   In these experiments, we captured source/destination address, port
   number, amount of traffic and start/end time to see flow information.

   60 Dummy nodes are put on access networks that are closest subscriber
   as possible in different 40 ISP networks.

   ||| P2P Application  |||
   |||    WindowsXP     |||
   |||        +--+      |||
   ||+--------|N |------+||
   ||  VMware |e |       ||
   |+---------|t |-------+|
   |   Linux  |IF| capture|
   +----------|  |--------+

   Dummy nodes

                                 Figure 1

5.  Hint Server ('08)

   In Japan, bottleneck in IP networks have been shifting 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 these circumstances, the Council proposed a less
   restrictive and more flexible cooperation between ISPs than existent
   P4P experiments [12].  The proposed method consists of the following
   elements: (1) P2P clients, (2) P2P control servers, and (3) a hint
   server: a peer selection 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 ALTO Server.  Note that this proposal

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   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 geographical districts or ISPs through
   providing information about the physical network to P2P applications.

   When a peer joins the network, it registers its location information
   (IP address) and supplementary information (line speed, etc.) with&#
   12288;the hint server.  The hint server calculate network distance
   between peers (P2P client) based on network topology information
   obtained from the ISP and generates a priority table for peer
   selection.  The hint server returns the table to the peer.

   If all information can be made publicly, 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
   experiments 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 difficulties to achieve
   coordination among providers.  In consideration of these
   difficulties, the council has been limiting the implementation and
   experiments to the following scope since 2006.

   Figure 2 shows an outline of the hint server.

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   +---------+   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 |-->| +--Priority Node Selection System--+ |
   |         |  |    List   |   | |                                  | |
   |         |  +-----------+   | |     Peer candidate ranking       | |
   |         |  +-----------+   | |                                  | |
   |         |--|  Ranking  |-->| +----------------------------------+ |
   |         |  +-----------+   +--------------------------------------+

                        Peer selection hint server

                                 Figure 2

   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 target 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.

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                      | 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)

      AS path length calculated from BGP full routes.  Since a full
      routing table retrieved at an ISP can show only a best path, it
      may not get an accurate length if the AS hop of both ISPs is too
      large.  To avoid this, we use multiple BGP information received
      from different ISPs and combine them.  Based on this concept, we
      used BGP routing information's offered by three ISPs operated by
      big telecommunication couriers and made a topology tree.  Then it
      enables to calculate the shortest path between given two ASes.

   o  Geographical 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.

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      The geographical distance is only used when the AS path length is

   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_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]

   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
      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

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6.  High-Level Trial Results

6.1.  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.

   In these two experiments we evaluate different P2P applications, in
   1st experiment, the P2P topology is generated by tree algorithm, and
   in 2nd experiment, it is generated by mesh algorithm.  Both of them
   result in similar performance.

   | 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 these experiments 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.

6.2.  Peer Selection with the Hint Server

   The main objective of these experiments was to verify the operations
   of the hint server and P2P applications.  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 95th percentile was reduced by 5%.  The
   results show introducing hint server can reduce network loads by P2P

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7.  Considerations

   We clarified followings throughout our experiments.

   1.  Dispersed dummy nodes can figure out the behavior of peers and
       traffic between inter-ISP networks, which peers are selected by
       each peer.  Therefore it proves that the importance of peer
       selection control mechanism proposed in ALTO.

   2.  Using our peer selection control mechanism, called hint server,
       could achieve significant differences.  Our hint server can lead
       each peer to select nearer peer.

   3.  The result of 10% reduction of network cost is not satisfying
       effect for ISPs, but the controllability for P2P applicationis
       most important point.  When they apply this mechanism for their
       real ISP network, they will set very large cost for most
       expensive network link.

   In the experimental result of peer selection control, it is smaller
   in intra-ISP traffic than other experiments [13] We think that it is
   because there are smaller peers in each area of traffic control.
   When there are many peers in one ISP, it is easy to select peers in
   the same ISP.  However, when there are small peers in one ISP, it is
   difficult to select peers in the same ISP.  In the situation of our
   experiments, there are many ISPs of peers belonging, and there are
   relatively smaller peers exist in same ISP.

   Moreover, we didn't force P2P vendors to limit their implementation
   policy, therefore we can observe differences how each implementations
   weigh the information from the hint servers.  Especially, in tree
   overlay topology P2P applications, such mechanism is very effective,
   on the other hand, in mesh overlay system, less effective.

7.1.  Next steps

   Recent research, we've changed the communication protocol to hint
   servers to ALTO based because it is nearly standardized.  In our
   implementation, PIDs and the value of cost are mapped to ISP subnets,
   and ISP distance respectively.  We also implement services for
   compatibility required by ALTO such as Service Capability and Map
   Services.  But the Endpoint Cost Service is mainly used because of
   backward compatibility of our experiments.

   We also study hierarchical hint server structure, in order to control
   in coarse inter-ISPs and in detail intra-ISP.  It is also effective
   for limiting the area of information disclose.

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7.2.  Feedback to ALTO WG

   This section describes what the authors learned with these
   experiments would be useful for the ALTO WG.

7.2.1.  Hierarchical architecture for ALTO servers

   In our experiments, we present the possibility of traffic control
   among multi-ISPs and multi-P2P applications using ALTO mechanism.  On
   the other hand, we found several problems in ISP operations to adapt
   the mechanism.  One is the granularity of network information from
   council members.  Among inter-ISP area, it is relatively easy to
   treat information for public purpose using BGP full route.  On the
   other hand, among intra-ISP area, it may be difficult to disclose
   private information of each ISP. [14] propose some modification for
   ALTO protocol in order to hide ISP information.  We propose
   hierarchical structures.  From the viewpoint of cooperation between
   ISPs, fine-grained information is not necessarily required and
   moreover it is difficult to exchange the fine-grained information
   between ISPs.  Considering this situation, the authors use only
   coarse-grained information to control backbone traffic in this
   experiments, though demand of controlling traffic within an ISP using
   fine-grained information may arise in future.  Therefore it led us
   that introducing hierarchical structure into ALTO is necessary to
   cope with both situations.  Actually, to adapt a hierarchical control
   mechanism which include the following two steps will be useful.

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

   o  Next, fine-grained information within the ISP is used to select a

7.2.2.  Measurement mechanism

   In the 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.

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8.  Security Considerations

   This document does not propose any kind of protocol, practice or

9.  IANA Considerations

   No need to describe any request regarding number assignment.

10.  Acknowledgments

   Thanks to strong support by MIC (Ministry of Internal Affairs and
   Communications of Japanese government), the council was established.
   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
   experiments.  The authors appreciate Tohru Asami, Hiroshi Esaki and
   Tatsuya Yamshita for their constructive comments.

   And the authors would like to thank Martin Stiemerling, Stefano
   Previdi and Vijay K.Gurbani for the comments on this document.

11.  Informative References

   [1]   R.Kawahara, E.K.Lua, M.Uchida, S.Kamei, H.Yoshino, "On the
         Quality of Triangle Inequality Violation Aware Routing Overlay
         Architecture",  INFOCOM 2009: 2761-2765.

   [2]   Z.Li, "QRON: QoS-aware routing in overlay networks",  IEEE
         JANUARY 2004.

   [3]   Sandvine Corp, "Global Internet Phenomena Report: 1H 2012",
         September 2012,

   [4]   "Winny on Wikipedia", <http://en.wikipedia.org/wiki/Winny>.

   [5]   "Share on Wikipedia",

   [6]   Taniwaki, "Broadband Competition Policy in Japan", 2008,

   [7]   Ministry of Internal Affairs and Communications, "Disclosure of

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         the Report `Working Group on P2P Networks'",
         2007 (in Japanese).

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

   [9]   Utagoe Inc., "UGLive technology introduction",
         March, 2011.

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

   [11]  Cho, Fukuda, Esaki, and Kato, "The Impact and Implications of
         the Growth in Residential User-to-User Traffic",  SIGCOMM2006,
         pp207-218, Pisa, Italy, September 2006.

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

   [13]  "RFC5632: Comcast's ISP Experiences in a Proactive Network
         Provider Participation for P2P (P4P) Technical Trial",
         September 2009.

   [14]  "ALTO H12,draft-kiesel-alto-h12-02 (work in progress)", March

Authors' Addresses

   Satoshi Kamei
   NTT Communications Corporation
   Granpark Tower 17F, 3-4-1 Shibaura
   Minato-ku, Tokyo  108-8118

   Phone: +81-50-3812-4697
   Email: skame@nttv6.jp

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   Tsuyoshi Momose
   Cisco Systems G.K.
   9-7-1 Akasaka
   Minato-ku, Tokyo  107-6227

   Phone: +81-3-6738-5154
   Email: tmomose@cisco.com

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

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

   Tomohiro Nishitani
   NTT Communications
   1-1-6, Uchisaiwaicho
   Chiyodaku, Tokyo  100-8019

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

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