Internet Research Task Force (IRTF)                             S. Kamei
Request for Comments: 6875                            NTT Communications
Category: Informational                                        T. Momose
ISSN: 2070-1721                                            Cisco Systems
                                                                T. Inoue
                                                            T. Nishitani
                                                      NTT Communications
                                                           February 2013

The P2P Network Experiment Council's Activities and Experiments with Application-Layer Traffic Optimization (ALTO) in Japan




This document describes experiments that clarify how an approach similar to Application-Layer Traffic Optimization (ALTO) was effective in reducing network traffic. These experiments were performed in Japan by the P2P Network Experiment Council in an attempt to harmonize peer-to-peer (P2P) technology with network infrastructure. Based on what was learned from these experiments, this document provides some suggestions that might be useful for the ALTO architecture and especially for application-independent ALTO-like server operation.


Status of This Memo


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

このドキュメントはInternet Standards Trackの仕様ではありません。情報提供を目的として公開されています。

This document is a product of the Internet Research Task Force (IRTF). The IRTF publishes the results of Internet-related research and development activities. These results might not be suitable for deployment. This RFC represents the individual opinion(s) of one or more members of the Peer-to-Peer Research Group of the Internet Research Task Force (IRTF). Documents approved for publication by the IRSG are not a candidate for any level of Internet Standard; see Section 2 of RFC 5741.

この文書は、Internet Research Task Force(IRTF)の製品です。 IRTFは、インターネット関連の研究開発活動の結果を公開しています。これらの結果は、展開に適さない可能性があります。このRFCは、インターネットリサーチタスクフォース(IRTF)のピアツーピアリサーチグループの1人以上のメンバーの個々の意見を表します。 IRSGによる公開が承認されたドキュメントは、どのレベルのインターネット標準の候補にもなりません。 RFC 5741のセクション2をご覧ください。

Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at


Copyright Notice


Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved.

Copyright(c)2013 IETF Trustおよびドキュメントの作成者として識別された人物。全著作権所有。

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

この文書は、BCP 78およびこの文書の発行日に有効なIETF文書に関するIETFトラストの法的規定(の対象となります。これらのドキュメントは、このドキュメントに関するあなたの権利と制限を説明しているため、注意深く確認してください。

Table of Contents


   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Background in Japan  . . . . . . . . . . . . . . . . . . . . .  4
     2.1.  P2P Traffic  . . . . . . . . . . . . . . . . . . . . . . .  4
     2.2.  Impact on Network Infrastructure . . . . . . . . . . . . .  4
     2.3.  Overview of the P2P Network Experiment Council . . . . . .  5
   3.  Objectives of the P2P Network Experiment Council . . . . . . .  6
   4.  Details of the Experiment  . . . . . . . . . . . . . . . . . .  7
     4.1.  Dummy Node . . . . . . . . . . . . . . . . . . . . . . . .  7
   5.  Hint Servers . . . . . . . . . . . . . . . . . . . . . . . . .  9
   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 the ALTO WG  . . . . . . . . . . . . . . . . . 15
       7.2.1.  Hierarchical Architecture for ALTO Servers . . . . . . 15
       7.2.2.  Measurement Mechanism  . . . . . . . . . . . . . . . . 15
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 16
   9.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 16
   10. Informative References . . . . . . . . . . . . . . . . . . . . 16
1. Introduction
1. はじめに

An overlay network, which is used by P2P and other applications, offers the advantage of allowing flexible provisioning of services while hiding the lower-layer network. The disadvantage is that inefficient routing without considering the lower-layer network may cause increasing the network load. Several proposals have been made to build an overlay network that takes into account 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 to optimize a network, without the cooperation of network providers.

P2Pやその他のアプリケーションで使用されるオーバーレイネットワークには、下位層のネットワークを隠しながら、サービスを柔軟にプロビジョニングできるという利点があります。欠点は、下位層のネットワークを考慮しない非効率的なルーティングにより、ネットワーク負荷が増大する可能性があることです。下位層ネットワークに関する情報を考慮したオーバーレイネットワークを構築するために、いくつかの提案がなされています[1] [2]。インターネットの管理は高度に分散されているため、ネットワークプロバイダーの協力なしに、このような提案を実装してネットワークを最適化することは困難です。

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 into account the network topology information obtained from network providers.


One research effort regarding this issue were experiments planned and performed by the P2P Network Experiment Council in Japan. This document reports on these experiments and the issues they addressed.


These experiments were performed from 2007 to 2008, because P2P traffic decreased after Japanese copyright law was revised. While more recently, the dominant traffic in Japan, the United States, and elsewhere has been HTTP-based flash streaming, a large amount of traffic in Asia (outside Japan) is still P2P traffic, like P2P streaming [3], and P2P technology is very useful in such a real-time 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 a generic measurement mechanism is important because each application has different mechanism, which makes it difficult to compare their effectiveness.


This document is a product of the P2P Research Group (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.

このドキュメントは、P2P Research Group(RG)の製品です。このドキュメントの見解は、P2P RGによって議論の余地があると見なされましたが、RGは、ドキュメントを引き続き公開する必要があるというコンセンサスに達しました。

2. Background in Japan
2. 日本の背景
2.1. P2P Traffic
2.1. P2Pトラフィック

As of 2008, the world's most popular P2P file-sharing application, BitTorrent, was not widely deployed in Japan. Instead, other file-sharing P2P applications specific to Japan, such as Winny [4] and Share [5], still account for 40% of the Internet traffic in Japan, even though many those P2P users were arrested for sharing illegal files with these P2P applications.

2008年現在、世界で最も人気のあるP2Pファイル共有アプリケーションであるBitTorrentは、日本ではあまり普及していません。その代わり、Winny [4]やShare [5]など、日本固有のその他のファイル共有P2Pアプリケーションは、日本でのインターネットトラフィックの40%を占めていますが、これらのP2Pユーザーの多くは、これらと違法ファイルを共有したとして逮捕されました。 P2Pアプリケーション。

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


2.2. Impact on Network Infrastructure
2.2. ネットワークインフラストラクチャへの影響

One 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 reduces 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 by using P2P technology for reducing server cost. Another problem for network providers is that extremely inefficient routing may be selected 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 remarkably increases the volume of traffic per user.


Faced with an increase in the load on network infrastructure, network providers are compelled to take actions to overcome the sudden increase in facilities' costs. Representative actions include placing content in Internet Exchanges (IXs) or data centers, introducing bandwidth control, and raising access fees [6].


As mentioned above, the dominant traffic currently in Japan, the US, and elsewhere, is HTTP-based flash streaming. However, a large amount of traffic in Asia (outside Japan) is P2P traffic, like P2P Streaming [3], and P2P technology is very useful in such real-time streaming. The increase in traffic arising from such a shift may be a great threat to the network.


2.3. Overview of the P2P Network Experiment Council
2.3. P2Pネットワーク実験評議会の概要

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


The council developed regulations that include guidelines such as giving advance notice to heavy users before restricting their bandwidth. In accordance with the regulations, some ISPs introduced solutions that reduce traffic caused by P2P file-sharing applications.


In addition, the council, along with ISPs, carriers, contents providers, and P2P system vendors, looked for new ways to control traffic by commercial P2P applications. In this work, the council performed experiments that introduced an ALTO-like system and observed how the traffic was reduced when it was redirected to proper peers on the real Internet in Japan.


In our experiment, the council deployed hint servers, which are described in Section 5. Hint servers run a protocol that offers network distances to peers, and these distances are disclosed to P2P application vendors.


Using hint servers, P2P application vendors can introduce ALTO concepts easily into their P2P distribution systems. Because the protocol used by hint servers, as defined by the council, is independent of specific P2P application vendors like BitTorrent. The protocol needs to gather network information from ISPs so it can provide network distance to peers. However, many ISPs dislike disclosing such information to others. Therefore, hint servers are designed to offer little information about an ISP's network architecture to P2P application vendors.


To monitor the traffic of peers, the council also deployed a dummy node, which is described in Section 4.1.


The remainder of this memo provides an overview of the experiments.


3. Objectives of the P2P Network Experiment Council
3. P2Pネットワーク実験評議会の目的

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 in 2006 and 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 the 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 it formed a "Working Group on the P2P Network", which carried out an intensive study of P2P networks.

日本の情報通信システムを管轄する総務省は、2006年と2007年にネットワーク中立性に関する諮問委員会を開催し、次世代ネットワークの確保などの課題を検討ネットワークの使用における公平性、およびコスト負担における公平性の定義方法。パネルは、日本でのブロードバンドアクセスの急速な拡大に起因するバックボーンネットワークにおける差し迫ったトラフィック飽和の解決策としてP2Pテクノロジーに関心を持ち、集中的な研究を行った「P2Pネットワークに関するワーキンググループ」を結成しました。 P2Pネットワークの。

The working group reported that it would be necessary to undertake the following four activities, which are intended to encourage the government to adopt relevant policies [7]:


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

o P2Pファイル配信アプリケーションに関するガイドラインを策定し、業界が自ら課すようにします。

o Promote feasibility tests of P2P networks.

o P2Pネットワークの実現可能性テストを促進します。

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

o 交通管制の現状を把握し、情報共有を推進する。

o Hold working group meetings about traffic control.

o 交通規制に関するワーキンググループ会議を開催します。

The first two proposals led to the establishment of the P2P Network Experiment Council, supported by the Japanese Ministry of Internal Affairs and Communications [8] [9]. 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 (Proactive Network Provider Participation for P2P), which takes a relatively top-down approach of adopting an architecture based on a proposal from a university, the Council is characterized by its bottom-up approach. The aim of establishing the Council was described as follows (translated from [10]).

最初の2つの提案は、日本の総務省によってサポートされたP2Pネットワーク実験評議会の設立につながりました[8] [9]。カウンシルは、P2P配信プロバイダー、コンテンツホルダー、ネットワークプロバイダーのメンバーで構成され、さまざまな配信実験を開始しました。これは、異なるレイヤー間の協調制御を強化することが期待されていました。大学からの提案に基づいてアーキテクチャを採用する比較的トップダウンのアプローチを取るP4P(P2Pのプロアクティブネットワークプロバイダー参加)とは対照的に、理事会はそのボトムアップアプローチが特徴です。評議会の設立の目的は次のとおりです([10]から翻訳)。

The rapid growth of broadband access enables content delivery systems 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.

ブロードバンドアクセスの急速な成長により、コンテンツ配信システムは高品質で大量のビデオを安全かつ効率的に配信できます。 P2P技術はこの要件に対して効果的な技術ですが、それでも対処すべきいくつかの問題があります。そこで、総務省の支援を得て「マルチメディア通信財団(FMMC)」内に事務局を設置する「P2Pネットワーク実験協議会」を設置し、事業者向けガイドラインの策定とフィージビリティテストを実施しました。ユーザーが安全にビデオ配信サービスを受けることができるように。

The activities of the P2P Network Experiment Council can be classified into two categories. The first is formulating guidelines for promoting the commercial use of P2P technology. These guidelines will enable users to use P2P technology safely and will give providers clear rules they must observe. The second is feasibility testing of P2P technology. Section 4 describes experiments conducted in 2007 and 2008.

P2Pネットワーク実験評議会の活動は、2つのカテゴリに分類できます。 1つ目は、P2P技術の商用利用を促進するためのガイドラインを策定することです。これらのガイドラインにより、ユーザーはP2Pテクノロジーを安全に使用できるようになり、プロバイダーが遵守しなければならない明確なルールが提供されます。 2つ目は、P2Pテクノロジーの実現可能性テストです。セクション4では、2007年と2008年に行われた実験について説明します。

4. Details of the Experiment
4. 実験の詳細

The Council investigated data offered by the members of the Council and learned that the server cost could be reduced by using P2P technology for content delivery. For example, the data from the vendors showed the following:


Traffic was reduced by 90% with UGLive by Utagoe, Inc. [11].


The cost of delivering to tens of thousands of subscribers was reduced by 80% with BBbroadcast with TV Bank Corp. [12]

TV Bank Corp.とのBBbroadcastにより、数万人の加入者への配信コストが80%削減されました。[12]

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


In order to visualize the reduction of network cost, we modeled P2P applications and a multi-ISP environment. This model was also needed for visualizing the effectiveness of the ALTO-like approach.


4.1. Dummy Node
4.1. ダミーノード

As mentioned above, while the effect of using P2P technology to reduce the traffic and the load on servers is well known; however, traffic behavior in the inter-ISP area is not known. In Japan, the ISPs and IXes cooperated to create a backbone traffic report [13]. However, the measurements gathered for that report required capturing packets on subscribers' lines in order to determine the end users' activities. 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 running P2P applications. Every P2P node provided by participating vendors in the experiment was configured so it always contacted the hint server.


By introducing dummy nodes and measuring the traffic on them, we were able to observe and evaluate how much the P2P applications affected the networks. Since this method can't measure every subscriber's traffic, the accuracy is less than other methods. However, using dummy nodes makes it possible to adapt to situations in which many different P2P applications coexist on a network. We decided that using dummy nodes was suitable for these experiments.


A dummy node consisted of an Intel PC server running Linux (CentOS), VMWare, and Windows XP on VMWare. With this configuration, all packets can be captured without any impact on the behavior of the network, nodes, or applications. Also, this configuration enabled us to use different P2P applications for Windows and evaluate them generally.

ダミーノードは、Linux(CentOS)、VMWare、およびVMWare上のWindows XPを実行するIntel PCサーバーで構成されていました。この構成では、ネットワーク、ノード、またはアプリケーションの動作に影響を与えることなく、すべてのパケットをキャプチャできます。また、この構成により、Windows用のさまざまなP2Pアプリケーションを使用して、それらを一般的に評価することができました。

To see behaviors of the node, incoming and outgoing packets are captured on Linux because every packet is transmitted through it. To see flow information in these experiments, we captured the source and destination addresses, port number, amount of traffic, and start and end times.


We placed 60 dummy nodes on access networks of 40 different ISPs. They were placed as close as possible to the subscriber in each network.


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

Figure 1: Dummy node


5. Hint Servers
5. ヒントサーバー

Since fiber to the home (FTTH) has rapidly spread all over Japan, bottlenecks in IP networks have been shifting from access networks to backbone networks and equipment, such as bandwidth between ISPs and capacity in IXs. Under these circumstances, the Council proposed less restrictive and more flexible cooperation between ISPs than existent P4P experiments [14]. The proposed method consists of the following elements: (1) P2P clients, (2) P2P control servers, and (3) a hint server (specifically, a peer selection hint server). P2P clients and control servers are existing systems, but whether the P2P control servers exist is application dependent. The hint server is a server that provides a hint for peer selection and plays a role equivalent to that of the ALTO server. 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 geographical districts or ISPs by providing information about the physical network to P2P applications.

ファイバー・トゥ・ザ・ホーム(FTTH)が日本中に急速に広まったため、IPネットワークのボトルネックは、アクセスネットワークからバックボーンネットワークおよびISP間の帯域幅やIXの容量などの機器にシフトしています。これらの状況下で、理事会は、既存のP4P実験よりもISP間の制限が少なく柔軟な協力を提案しました[14]。提案された方法は、次の要素で構成されています:(1)P2Pクライアント、(2)P2Pコントロールサーバー、および(3)ヒントサーバー(具体的には、ピア選択ヒントサーバー)。 P2Pクライアントと制御サーバーは既存のシステムですが、P2P制御サーバーが存在するかどうかはアプリケーションによって異なります。ヒントサーバーは、ピア選択のヒントを提供し、ALTOサーバーと同等の役割を果たすサーバーです。この提案は、ダミーノードを使用した実験結果に基づいていることに注意してください。結果は、物理ネットワークに関する情報をP2Pアプリケーションに提供することにより、地理的地区またはISPの境界を越えて流れる不要なトラフィックを削減できることを示しました。

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 calculates the network distance between peers (P2P clients) 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 is public, the above procedure can produce results that are nearly optimal. However, some information held by ISPs is often confidential. Also, in some cases, the volume of calculation required to process all information can be excessive. To avoid these problems, the plan is to conduct experiments with a limited set of functions, analyze the 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 requires coordination among providers. In light of these difficulties, the council has been limiting the implementation and experiments to the technical scope.


Figure 2 shows an outline of the hint server.


   +---------+   GetLocation    +-------------GeoIP DB Server---------+
   |         |  +-----------+   |   +----------+      +-----------+   |
   |         |--|IP Address |-->|   | GeoIP DB |      |BGP daemon |   |
   |         |  +-----------+   |   +----------+      +-----------+   |
   |         |                  | +-------------+  +----------------+ |
   |         |  +-----------+   | |  District   |  |    Routing     | |
   |         |--|AS Code:   |---| | Information |  |Information(BGP)| |
   |         |  |Regional   |   | |             |  |                | |
   |P2P Peers|  |Information|   | |   Range of  |  |AS Code(origin) | |
   |   or    |  +-----------+   | | IP Addresses|  |                | |
   | Control |                  | +-------------+  +----------------+ |
   | Server  |                  +-------------------------------------+
   |         |                                  |      ^
   |         |  PeerSelection                   v      |
   |         |  +-----------+   +--------------------------------------+
   |         |--|IP Address |-->| +--Priority Node Selection System--+ |
   |         |  |    List   |   | |                                  | |
   |         |  +-----------+   | |     Peer Candidate Ranking       | |
   |         |  +-----------+   | |                                  | |
   |         |--|  Ranking  |-->| +----------------------------------+ |
   |         |  +-----------+   +--------------------------------------+

Figure 2: Hint server for peer selection


The network information used by the hint server is not information solicited from individual ISPs but is the Autonomous System (AS) number and district information, which are more or less public already. 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, in order to confine the traffic to within the nearer ISP or district. A peer can select another 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 the percentage of peers within the same AS or the same prefecture calculated from the distribution of ASes and prefectures in the IP address space from one-day data on a Winny network.


                    | Conditions         | Percentage |
                    | AS matches         |    6.70%   |
                    | Prefecture matches |   12.76%   |
                    | Both match         |    2.09%   |
                    | Neither match      |   78.45%   |

Table 1: AS and prefecture distributions


Because, in addition to the above, the presence or absence of content affects the results, controlling peer selection 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 this, the following two measures are used to evaluate the proximity of peers in a hint server.


o AS path length (distance between ISPs)

o ASパスの長さ(ISP間の距離)

AS path length is 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 count of both ISPs is too large. To avoid this, we use BGP information received from different ISPs and combine them. Based on this concept, we used BGP routing information offered by three ISPs operated by big telecommunication couriers and made a topology tree. Then, we were able to calculate the shortest path between two given ASes.

ASパス長は、BGPフルルートから計算されます。 ISPで取得された完全なルーティングテーブルには最適なパスしか表示されないため、両方のISPのASホップカウントが大きすぎると、正確な長さが得られない場合があります。これを回避するために、異なるISPから受信したBGP情報を使用して、それらを結合します。このコンセプトに基づいて、大手通信業者が運営する3つのISPから提供されるBGPルーティング情報を使用して、トポロジーツリーを作成しました。次に、2つの特定のAS間の最短経路を計算することができました。

o Geographical distance

o 地理的距離

Distances between peers are measured using the physical distance between the capitals of the prefectures to which the peers belong. Distances between prefectural capitals are sorted into ascending order, and then into bands, with weights 1 to 15 assigned to them so that each band contains roughly the same number of "capital pairs". If either of the peer's locations is indefinite, the distance is equal to 15; if they are in the same prefecture, the 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. The geographical distance is used only when the AS path length is the same between some candidates.


An example of the request and the response follows.


o Request

o リクエスト

      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=transaction ID]
      [pt=Flag of port type]
      [ub=upload bandwidth]
      [db=download bandwidth]

o Response

o 応答

     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 responding peers n=[src address] dst address / cost / option

v =バージョン番号ttl = ttl server =ヒントサーバー名... trans_id =トランザクションID pt =ポートタイプのフラグclient_ip =サーバーから観測されたピアIPアドレスclient_port =サーバーから観測されたピアポート番号numpeers =応答するピアの数n = [ src address] dst address / cost / option

6. High-Level Trial Results
6. 高レベルの試験結果
6.1. Peer Selection with P2P
6.1. P2Pによるピア選択

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


In these two experiments, we evaluated different P2P applications. In the first experiment, the P2P topology was generated by a tree algorithm; in the second experiment, it was generated by a mesh algorithm. Both resulted in similar performance.

これら2つの実験では、異なるP2Pアプリケーションを評価しました。最初の実験では、P2Pトポロジはツリーアルゴリズムによって生成されました。 2番目の実験では、メッシュアルゴリズムによって生成されました。どちらも同様のパフォーマンスをもたらしました。

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

Table 2: Percentage of communication within the same ISP


Table 2 shows that the probability of communication with peers in the same ISP is proportional to the population size 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 demonstrated that the mechanism for selecting 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
6.2. ヒントサーバーによるピアの選択

The main objective of these experiments was to verify the operation 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 the mean value of distance after the hint server was introduced was reduced by 10% and that the 95th percentile was reduced by 5%. The results show that introducing a hint server can reduce the network loads that result from P2P applications.


7. Considerations
7. 考慮事項

We clarified the following during our experiments.


1. Dispersed dummy nodes can determine the behavior of peers and traffic between inter-ISP networks and can determine the peer that each peer selects. Therefore, this result proves the importance of the peer-selection control mechanism that is proposed by ALTO.

1. 分散したダミーノードは、ピアの動作とISP間ネットワーク間のトラフィックを決定し、各ピアが選択するピアを決定できます。したがって、この結果は、ALTOによって提案されたピア選択制御メカニズムの重要性を証明しています。

2. Using our peer-selection control mechanism, called hint servers, can result in significant differences. Hint servers can lead each peer to select a closer peer.

2. ヒントサーバーと呼ばれるピア選択制御メカニズムを使用すると、大きな違いが生じる可能性があります。ヒントサーバーは、各ピアをより近いピアを選択するように導くことができます。

3. The 10% reduction of network cost is not satisfactory for ISPs, but the controllability of P2P applications is the most important point. When ISPs apply this mechanism to their real networks, they will set a very large cost for the most expensive network link.

3. ネットワークコストの10%削減はISPにとって満足のいくものではありませんが、P2Pアプリケーションの制御性が最も重要なポイントです。 ISPがこのメカニズムを実際のネットワークに適用すると、最も高価なネットワークリンクに非常に大きなコストがかかります。

In the experimental results for peer-selection control, the selection is smaller in intra-ISP traffic than in other experiments [15]. We think this is because there are fewer 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 fewer peers in one ISP, it is difficult to select peers in the same ISP. In our experiments, most of the ISPs had many peers in their networks, i.e., there were a small number of ISPs that had few peers in their networks.

ピア選択制御の実験結果では、ISP内トラフィックの選択は他の実験よりも小さくなります[15]。これは、トラフィック制御の各領域にピアが少ないためと考えられます。 1つのISPにピアが多数ある場合、同じISPのピアを選択するのは簡単です。ただし、1つのISP内のピアが少ない場合、同じISP内のピアを選択することは困難です。私たちの実験では、ほとんどのISPはネットワーク内に多くのピアを備えていました。つまり、少数のISPがネットワーク内のピアをほとんど備えていませんでした。

Moreover, we didn't force P2P vendors to limit their implementation policy; therefore, we observed differences in how each implementation weighs the information from the hint servers. Specifically, in P2P applications when a tree topology is used, the hint-server mechanism is very effective; on the other hand, when a mesh topology is used, it less effective.


7.1. Next Steps
7.1. 次のステップ

In recent research, we've changed to an ALTO-based communication protocol on hint servers because the requirements of ALTO are documented in RFC 6708 [16] and the ALTO protocol is a work in progress [17]. In our implementation, protocol identifiers (PIDs) and the cost value are mapped to ISP subnets and to ISP distance, respectively. We also implement services for compatibility required by ALTO such as Map Services and Endpoint Cost Service. The Endpoint Cost Service (defined in [17]) is mainly used because of backward compatibility with our experiments.

最近の調査では、ヒントサーバーでALTOベースの通信プロトコルに変更しました。ALTOの要件はRFC 6708 [16]に文書化されており、ALTOプロトコルは進行中の作業[17]であるためです。この実装では、プロトコル識別子(PID)とコスト値は、それぞれISPサブネットとISP距離にマップされます。マップサービスやエンドポイントコストサービスなど、ALTOに必要な互換性のためのサービスも実装します。 Endpoint Cost Service([17]で定義)は、実験との下位互換性のために主に使用されます。

We are also studying a hierarchical structure of hint servers, in order to control traffic at a coarse level (in inter-ISP areas) and at a finer level (in intra-ISP areas). It is also effective for limiting the areas where information is disclosed.


7.2. Feedback to the ALTO WG
7.2. ALTO WGへのフィードバック

This section describes what the authors learned from these experiments that might be useful to the ALTO WG.

このセクションでは、ALTO WGに役立つ可能性があるこれらの実験から著者が学んだことについて説明します。

7.2.1. Hierarchical Architecture for ALTO Servers
7.2.1. ALTOサーバーの階層アーキテクチャ

In our experiments, we present the possibility of traffic control among multiple ISPs and multiple P2P applications using an ALTO mechanism. We found several problems when ISPs try to adopt the mechanism. One is the granularity of network information from Council members. Among inter-ISP areas, it is relatively easy to handle information for public purposes by using BGP full routes. On the other hand, among the intra-ISP areas, it may be difficult to disclose the private information of each ISP. Kiesel [18] proposes some modifications for the 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. Moreover, it is difficult to exchange the fine-grained information between ISPs. Considering this situation, we used only coarse-grained information to control backbone traffic in these experiments; however, in the future, there may be a demand for controlling traffic within an ISP using fine-grained information. Therefore, we decided to introduce hierarchical structures into ALTO in order to cope with both situations. Actually, adopting a hierarchical control mechanism that includes the following two steps will be useful.

私たちの実験では、ALTOメカニズムを使用して、複数のISPおよび複数のP2Pアプリケーション間のトラフィック制御の可能性を示します。 ISPがこのメカニズムを採用しようとしたときに、いくつかの問題が見つかりました。 1つは、評議会メンバーからのネットワーク情報の粒度です。 ISP間エリアの中で、BGPフルルートを使用することにより、公的な目的で情報を処理することは比較的簡単です。一方、ISP内では、各ISPの個人情報の開示が難しい場合があります。キーゼル[18]は、ISP情報を隠すためにALTOプロトコルのいくつかの変更を提案しています。階層構造を提案します。 ISP間の連携という観点からは、きめ細かな情報は必ずしも必要ではありません。また、ISP間のきめ細かな情報のやり取りが困難です。この状況を考慮して、これらの実験ではバックボーントラフィックを制御するために粗い情報のみを使用しました。ただし、将来的には、粒度の細かい情報を使用してISP内のトラフィックを制御する必要があるかもしれません。したがって、両方の状況に対処するために、ALTOに階層構造を導入することにしました。実際には、次の2つのステップを含む階層制御メカニズムを採用すると便利です。

o First, use coarse-grained information about whole the network to select ISPs.

o まず、ネットワーク全体に関する大まかな情報を使用して、ISPを選択します。

o Second, use fine-grained information within the ISP to select a peer.

o 次に、ISP内の詳細な情報を使用してピアを選択します。

7.2.2. Measurement Mechanisms
7.2.2. 測定メカニズム

In these experiments, there were two difficulties as follows.


o Evaluating the effect of introducing a hint server was difficult because the P2P applications had their own measurement mechanisms.

o ヒントサーバーを導入する効果を評価することは、P2Pアプリケーションに独自の測定メカニズムがあったため、困難でした。

o How to treat the priority order of peers suggested by a hint server could not be predetermined for P2P applications.

o ヒントサーバーによって提案されたピアの優先順位を処理する方法は、P2Pアプリケーションに対して事前に決定できませんでした。

From these experiences, the authors consider that clarifying the requirements about measurement mechanisms for P2P applications is necessary in ALTO.


8. Security Considerations
8. セキュリティに関する考慮事項

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


9. Acknowledgments
9. 謝辞

The P2P Network Experiment Council was established thanks to strong support by the Japanese Ministry of Internal Affairs and Communications. These experiments were performed with cooperation among the P2P Network Experiment Council members. DREAMBOAT Co., Ltd., Bitmedia, Inc., Utagoe, Inc., and Toyama IX have especially supported the analyses of the experiments. The authors appreciate Tohru Asami, Hiroshi Esaki, and Tatsuya Yamashita for their constructive comments.

P2Pネットワーク実験評議会は、総務省の強力な支援を受けて設立されました。これらの実験は、P2Pネットワーク実験評議会メンバーの協力を得て行われました。 DREAMBOAT Co.、Ltd.、Bitmedia、Inc.、Utagoe、Inc.、およびToyama IXは、実験の分析を特にサポートしています。著者は、建設的なコメントのために浅見徹、江崎博、山下達也に感謝します。

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

著者はまた、このドキュメントに対するコメントについて、Martin Stiemerling、Stefano Previdi、およびVijay K. Gurbaniに感謝します。

10. Informative References
10. 参考引用

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

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

[2] Li, Z. and P. Mohapatra, "QRON: QoS-aware routing in overlay networks", IEEE Journal on Selected Areas in Communications, Vol. 22, No. 1, January 2004.

[2] Li、Z。およびP. Mohapatra、「QRON:オーバーレイネットワークにおけるQoS対応ルーティング」、IEEE Journal on Communications on Selected Areas、Vol。 22、No。1、2004年1月。

[3] Sandvine, Inc., "Global Internet Phenomena Report: 2H 2012", September 2012, <>.

[3] Sandvine、Inc。、「Global Internet Phenomena Report:2H 2012」、2012年9月、<>。

[4] Wikipedia, "Winny", July 2012, < index.php?title=Winny&oldid=500744660>.

[4] Wikipedia、「Winny」、2012年7月、< index.php?title = Winny&oldid = 500744660>。

[5] Wikipedia, "Share (P2P)", January 2013, < index.php?title=Share_(P2P)&oldid=532999898>.

[5] Wikipedia、「Share(P2P)」、2013年1月、< index.php?title = Share_(P2P)&oldid = 532999898>。

[6] Taniwaki, Y., "Broadband Competition Policy in Japan", March 2008, < documents/apcity/unpan040329.pdf>.

[6] 谷脇幸子、「日本のブロードバンド競争政策」、2008年3月、<>。

[7] Ministry of Internal Affairs and Communications, "Disclosure of the Report 'Working Group on P2P Networks'" (in Japanese), 2007, <>.

[7] 総務省、「P2Pネットワークに関するワーキンググループの報告書」2007年、<。 html>。

[8] The Foundation for MultiMedia Communications, "The P2P Network Experiment Council" (in Japanese), 2007, <>.

[8] マルチメディア通信財団、「P2Pネットワーク実験評議会」(日本語)、2007年、<>。

[9] Ministry of Internal Affairs and Communications, "P2P Network Experiment Council Symposium to Be Held", February 2008, < Telecommunications/news080201_1.html>.

[9] 総務省、「P2Pネットワーク実験評議会シンポジウム開催」、2008年2月、< Telecommunications / news080201_1.html>。

[10] The Foundation for MultiMedia Communications, "The Aim of P2P Network Experiment Council" (in Japanese), 2007, <>.

[10] マルチメディア通信財団、「P2Pネットワーク実験会議の目的」、2007年、<>。

[11] Shudo, K., "A Review of ALM Software in Practical Use", IRTF SAMRG (Scalable Adaptive Multicast Research Group) meeting, Proceedings of IETF 76, November 2009, <>.

[11] Shudo、K.、 "A Review of ALM Software in Practical Use"、IRTF SAMRG(Scalable Adaptive Multicast Research Group)ミーティング、Proceedings of IETF 76、November 2009、< slides / SAMRG-6.pdf>。

[12] TV Bank Corp., "Live Delivery Using 'BB Broadcast' Achieved a 96% Saving in Traffic!" (in Japanese), October 2008, <>.

[12] TV Bank Corp。、「「BB Broadcast」を使用したライブ配信により、トラフィックが96%削減されました!」 (日本語)、2008年10月、<>。

[13] Cho, K., Fukuda, K., Esaki, H., and A. Kato, "The Impact and Implications of the Growth in Residential User-to-User Traffic", SIGCOMM '06, pages 207-218, September 2006.

[13] Cho、K.、Fukuda、K.、Esaki、H.、and A. Kato、 "The Impact and Impacts of Growth of Growth in Growth of Residential User-to-User Traffic"、SIGCOMM '06、pages 207-218、September 2006。

[14] Xie, H., Yang, R., Krishnamurthy, A., Liu, Y., and A. Silberscatz, "P4P: Provider Portal for Applications", SIGCOMM '08, pages 351-362, 2008, < projects/p4p/p4p-sigcomm08.pdf>.

[14] Xie、H.、Yang、R.、Krishnamurthy、A.、Liu、Y.、and A. Silberscatz、 "P4P:Provider Portal for Applications"、SIGCOMM '08、pages 351-362、2008、<http://>。

[15] Griffiths, C., Livingood, J., Popkin, L., Woundy, R., and Y. Yang, "Comcast's ISP Experiences in a Proactive Network Provider Participation for P2P (P4P) Technical Trial", RFC 5632, September 2009.

[15] Griffiths、C.、Livingood、J.、Popkin、L.、Woundy、R。、およびY. Yang、「ComcastのISPエクスペリエンスにおけるP2P(P4P)テクニカルトライアルのプロアクティブネットワークプロバイダー参加」、RFC 5632、2009年9月。

[16] Kiesel, S., Previdi, S., Stiemerling, M., Woundy, R., and Y. Yang, "Application-Layer Traffic Optimization (ALTO) Requirements", RFC 6708, September 2012.

[16] キーゼル、S。、プレビディ、S。、スティームリング、M。、ウウンディ、R。、およびY.ヤン、「アプリケーション層トラフィック最適化(ALTO)の要件」、RFC 6708、2012年9月。

[17] Alimi, R., Ed., Penno, R., Ed., and Y. Yang, Ed., "ALTO Protocol", Work in Progress, September 2012.

[17] Alimi、R.、Ed。、Penno、R.、Ed。、and Y. Yang、Ed。、 "ALTO Protocol"、Work in Progress、2012年9月。

[18] Kiesel, S. and M. Stiemerling, "ALTO H12", Work in Progress, March 2010.

[18] キーゼル、S。およびM.スティーマーリング、「ALTO H12」、Work in Progress、2010年3月。

Authors' Addresses


Satoshi Kamei NTT Communications Corporation Granpark Tower 16F, 3-4-1 Shibaura Minato-ku, Tokyo 108-8118 Japan

さとし かめい んっt こっむにかちおんs こrぽらちおん Gらんぱrk とうぇr 16F、 3ー4ー1 しばうら みなとーく、 ときょ 108ー8118 じゃぱん

   Phone: +81-50-3812-4697

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

つよし ももせ しsこ Sysてms G。K。 9ー7ー1 あかさか みなとーく、 ときょ 107ー6227 じゃぱん

   Phone: +81-3-6738-5154

Takeshi Inoue NTT Communications Corporation Kuredo Hakushima Building 3F, 14-15 Higashihakushimacho Chuo-ku, Hiroshima-City, Hiroshima 730-0004 Japan

たけし いのうえ んっt こっむにかちおんs こrぽらちおん くれど はくしま ぶいlぢんg 3F、 14ー15 ひがしはくしまちょ ちゅおーく、 ひろしまーしty、 ひろしま 730ー0004 じゃぱん

   Phone: +81-82-563-5030

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

ともひろ にしたに んっt こっむにかちおんs こrぽらちおん 1ー1ー6、 うちさいわいちょ ちよだく、 ときょ 100ー8019 じゃぱん

   Phone: +81-50-3812-4742