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authorThomas Voss <mail@thomasvoss.com> 2024-11-27 20:54:24 +0100
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+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
+
+Abstract
+
+ 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.
+
+ 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.
+
+ Information about the current status of this document, any errata,
+ and how to provide feedback on it may be obtained at
+ http://www.rfc-editor.org/info/rfc6875.
+
+
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+
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+Kamei, et al. Informational [Page 1]
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+RFC 6875 P2P Experiments in Japan February 2013
+
+
+Copyright Notice
+
+ Copyright (c) 2013 IETF Trust and the persons identified as the
+ document authors. All rights reserved.
+
+ This document is subject to BCP 78 and the IETF Trust's Legal
+ Provisions Relating to IETF Documents
+ (http://trustee.ietf.org/license-info) in effect on the date of
+ publication of this document. Please review these documents
+ carefully, as they describe your rights and restrictions with respect
+ to this document.
+
+Table of Contents
+
+ 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
+ 2. 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
+
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+Kamei, et al. Informational [Page 2]
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+RFC 6875 P2P Experiments in Japan February 2013
+
+
+1. Introduction
+
+ 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.
+
+ 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.
+
+
+
+
+
+
+
+
+
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+Kamei, et al. Informational [Page 3]
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+RFC 6875 P2P Experiments in Japan February 2013
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+
+2. Background in Japan
+
+2.1. P2P Traffic
+
+ 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.
+
+ 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
+
+ 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
+
+
+
+Kamei, et al. Informational [Page 4]
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+RFC 6875 P2P Experiments in Japan February 2013
+
+
+ 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
+
+ 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.
+
+
+
+
+
+
+
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+Kamei, et al. Informational [Page 5]
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+RFC 6875 P2P Experiments in Japan February 2013
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+3. Objectives of the 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 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.
+
+ 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 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 about 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 [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]).
+
+ 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
+
+
+
+
+
+Kamei, et al. Informational [Page 6]
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+RFC 6875 P2P Experiments in Japan February 2013
+
+
+ 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 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.
+
+4. Details of the Experiment
+
+ 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]
+
+ 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
+
+ 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.
+
+
+
+
+
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+
+ 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.
+
+ 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
+
+
+
+
+
+
+Kamei, et al. Informational [Page 8]
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+RFC 6875 P2P Experiments in Japan February 2013
+
+
+5. Hint Servers
+
+ 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.
+
+ 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.
+
+
+
+
+
+
+
+
+
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+Kamei, et al. Informational [Page 9]
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+RFC 6875 P2P Experiments in Japan February 2013
+
+
+ +---------+ 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.
+
+
+
+Kamei, et al. Informational [Page 10]
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+RFC 6875 P2P Experiments in Japan February 2013
+
+
+ +--------------------+------------+
+ | 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)
+
+ 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.
+
+ o Geographical distance
+
+ 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
+
+
+
+
+
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+RFC 6875 P2P Experiments in Japan February 2013
+
+
+ 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
+
+ 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=transaction 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
+ 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
+
+
+
+
+
+
+
+
+Kamei, et al. Informational [Page 12]
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+RFC 6875 P2P Experiments in Japan February 2013
+
+
+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 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.
+
+ +-----------------------------------------+------------+------------+
+ | 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
+
+ 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.
+
+
+
+
+
+
+Kamei, et al. Informational [Page 13]
+
+RFC 6875 P2P Experiments in Japan February 2013
+
+
+7. Considerations
+
+ 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.
+
+ 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.
+
+ 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.
+
+ 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.
+
+ 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
+
+ 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.
+
+
+
+Kamei, et al. Informational [Page 14]
+
+RFC 6875 P2P Experiments in Japan February 2013
+
+
+ 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
+
+ This section describes what the authors learned from these
+ experiments that might be useful to the ALTO WG.
+
+7.2.1. Hierarchical Architecture for ALTO Servers
+
+ 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.
+
+ o First, use coarse-grained information about whole the network to
+ select ISPs.
+
+ o Second, use fine-grained information within the ISP to select a
+ peer.
+
+7.2.2. Measurement Mechanisms
+
+ 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 How to treat the priority order of peers suggested by a hint
+ server could not be predetermined for P2P applications.
+
+
+
+Kamei, et al. Informational [Page 15]
+
+RFC 6875 P2P Experiments in Japan February 2013
+
+
+ From these experiences, the authors consider that clarifying the
+ requirements about measurement mechanisms for P2P applications is
+ necessary in ALTO.
+
+8. Security Considerations
+
+ This document does not propose any kind of protocol, practice, or
+ standard.
+
+9. Acknowledgments
+
+ 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.
+
+ The authors would also like to thank Martin Stiemerling, Stefano
+ Previdi, and Vijay K. Gurbani for their comments on this document.
+
+10. Informative References
+
+ [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.
+
+ [3] Sandvine, Inc., "Global Internet Phenomena Report: 2H 2012",
+ September 2012,
+ <http://www.sandvine.com/news/global_broadband_trends.asp>.
+
+ [4] Wikipedia, "Winny", July 2012, <http://en.wikipedia.org/w/
+ index.php?title=Winny&oldid=500744660>.
+
+ [5] Wikipedia, "Share (P2P)", January 2013,
+ <http://en.wikipedia.org/w/
+ index.php?title=Share_(P2P)&oldid=532999898>.
+
+ [6] Taniwaki, Y., "Broadband Competition Policy in Japan",
+ March 2008, <http://unpan1.un.org/intradoc/groups/public/
+ documents/apcity/unpan040329.pdf>.
+
+
+
+
+Kamei, et al. Informational [Page 16]
+
+RFC 6875 P2P Experiments in Japan February 2013
+
+
+ [7] Ministry of Internal Affairs and Communications, "Disclosure of
+ the Report 'Working Group on P2P Networks'" (in Japanese),
+ 2007,
+ <http://www.soumu.go.jp/menu_news/s-news/2007/070629_11.html>.
+
+ [8] The Foundation for MultiMedia Communications, "The P2P Network
+ Experiment Council" (in Japanese), 2007,
+ <http://www.fmmc.or.jp/P2P/about.htm>.
+
+ [9] Ministry of Internal Affairs and Communications, "P2P Network
+ Experiment Council Symposium to Be Held", February 2008,
+ <http://www.soumu.go.jp/main_sosiki/joho_tsusin/eng/Releases/
+ Telecommunications/news080201_1.html>.
+
+ [10] The Foundation for MultiMedia Communications, "The Aim of P2P
+ Network Experiment Council" (in Japanese), 2007,
+ <http://www.fmmc.or.jp/p2p_web/aim.html>.
+
+ [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,
+ <http://www.ietf.org/proceedings/76/slides/SAMRG-6.pdf>.
+
+ [12] TV Bank Corp., "Live Delivery Using 'BB Broadcast' Achieved a
+ 96% Saving in Traffic!" (in Japanese), October 2008,
+ <http://www.tv-bank.com/jp/20081031.html>.
+
+ [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.
+
+ [14] Xie, H., Yang, R., Krishnamurthy, A., Liu, Y., and A.
+ Silberscatz, "P4P: Provider Portal for Applications", SIGCOMM
+ '08, pages 351-362, 2008, <http://www.cs.yale.edu/homes/yry/
+ projects/p4p/p4p-sigcomm08.pdf>.
+
+ [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.
+
+ [16] Kiesel, S., Previdi, S., Stiemerling, M., Woundy, R., and Y.
+ Yang, "Application-Layer Traffic Optimization (ALTO)
+ Requirements", RFC 6708, September 2012.
+
+ [17] Alimi, R., Ed., Penno, R., Ed., and Y. Yang, Ed., "ALTO
+ Protocol", Work in Progress, September 2012.
+
+
+
+
+Kamei, et al. Informational [Page 17]
+
+RFC 6875 P2P Experiments in Japan February 2013
+
+
+ [18] Kiesel, S. and M. Stiemerling, "ALTO H12", Work in Progress,
+ March 2010.
+
+Authors' Addresses
+
+ Satoshi Kamei
+ NTT Communications Corporation
+ Granpark Tower 16F, 3-4-1 Shibaura
+ Minato-ku, Tokyo 108-8118
+ Japan
+
+ Phone: +81-50-3812-4697
+ EMail: skame@nttv6.jp
+
+
+ Tsuyoshi Momose
+ Cisco Systems G.K.
+ 9-7-1 Akasaka
+ Minato-ku, Tokyo 107-6227
+ Japan
+
+ Phone: +81-3-6738-5154
+ EMail: tmomose@cisco.com
+
+
+ Takeshi Inoue
+ NTT Communications Corporation
+ Kuredo Hakushima Building 3F, 14-15 Higashihakushimacho
+ Chuo-ku, Hiroshima-City, Hiroshima 730-0004
+ Japan
+
+ Phone: +81-82-563-5030
+ EMail: inoue@jp.ntt.net
+
+
+ Tomohiro Nishitani
+ NTT Communications Corporation
+ 1-1-6, Uchisaiwaicho
+ Chiyodaku, Tokyo 100-8019
+ Japan
+
+ Phone: +81-50-3812-4742
+ EMail: tomohiro.nishitani@ntt.com
+
+
+
+
+
+
+
+
+Kamei, et al. Informational [Page 18]
+