WO2012116582A1

WO2012116582A1 - P2p content distribution method and system

Info

Publication number: WO2012116582A1
Application number: PCT/CN2012/070410
Authority: WO
Inventors: 李漓春
Original assignee: 中兴通讯股份有限公司
Priority date: 2011-02-28
Filing date: 2012-01-16
Publication date: 2012-09-07
Also published as: CN102651757A

Abstract

Disclosed are a Peer to Peer (P2P) content distribution method and system. The method includes; a track server records the address of a content distribution node having content/a content fragment or participating in the distribution of content/a content fragment, and records the address of a storage server where the content/content fragment is stored; a second content distribution node queries a list of nodes having the specified content/content fragment or participating in the distribution of the specified content/content fragment from the track server, the track server returns a list of corresponding nodes to the second content distribution node, with the list of nodes at least including the address of a first storage server where the first content distribution node uploads the content/content fragment; the second content distribution node directly downloads the specified content/content fragment from the first storage server in the list of nodes, or downloads the same from the first storage server in the list of nodes via the second storage server. According to the present invention, the storage server can be fully utilized to reduce the traffic and improve the quality of service.

Description

Method and system for P2P content distribution

The present invention relates to content distribution technologies, and in particular, to a peer-to-peer (P2P, Peer to Peer) content distribution method and system. Background technique

The basic architecture of the P2P content distribution system consists of a tracker and a content distribution node. The tracker is also called a location server. The peer is a peer node. Usually all or most peers are user nodes. The tracker is managed. Peer and server for peer positioning. Common P2P content distribution systems include P2P systems using proprietary protocols such as BT (BitTorrent) and PPLive. Currently, the standard protocol for P2P content distribution is the P2P Peer to Peer Streaming Protocol (PPSP), which is being standardized by the Internet Engineering Task Force (IETF).

P2P content distribution traffic accounts for a large proportion of Internet traffic, and its large traffic brings network congestion. Network congestion affects users' P2P content distribution services and other services. The limited uplink bandwidth of users also limits the quality of P2P content distribution. P2P content distribution combined with the storage server can solve the above problems. Usually such a storage server is provided by a third party (usually a network operator), also known as a P2P cache. P2P content distribution combined with storage server has two ways, one is active storage mode, the storage server supports P2P protocol, and actively participates in content distribution; the other is passive storage mode, and the P2P content distribution system uses storage server storage that does not support P2P protocol. And forwarding content, such storage server representatives have IETF's application-independent data relay (DECADE, Decoupled Application Data Enroute) working group is standardizing the DECADE server. The passive storage mode does not require the storage server to support multiple P2P protocols, and does not require the storage server to be modified as the P2P protocol changes. As shown in FIG. 1, a P2P content distribution system using a storage server using a passive storage method includes a content distribution node (peer), a tracking server (tracker), and a storage server that does not support the P2P protocol. The content distribution node is used to upload and/or download content; the tracking server records the peer address participating in the content distribution, and can also record which content segments each peer owns; the storage server stores and distributes the content for the P2P content distribution system. Taking the system architecture shown in FIG. 1 as an example, the content distribution operation in the passive storage mode includes:

51. The content distribution node C joins the distribution group of the content by the tracking server, and reports the content/content fragment owned by the tracking server to the tracking server;

52. The content distribution node B joins the distribution group of the content by the tracking server, and reports the content/content fragment owned by the tracking server to the tracking server;

53. The content distribution node B uploads the content/content fragments it owns to the storage server to which it is connected;

54. The content distribution node A queries the tracking server for a peer list of downloadable content/content fragments;

55. The tracking server returns a peer list to the content distribution node A, where the peer list includes downloadable content/content fragment information and its corresponding peer address;

S6. The content distribution node A requests content/content fragments from the content distribution node C;

S7. The content distribution node C returns the content/content fragment to the content distribution node A;

S8. The content distribution node A requests the content distribution content B to the content distribution node B;

S9, the content distribution node B returns storage server information (including the address of the storage server, authentication information, etc.) to the content distribution node A;

S10. The content distribution node A uploads the content/content fragment storage server request content/content fragment to the content distribution node B;

S11. The storage server returns a content/content fragment to the content distribution node A.

Adopt P2P content distribution combined with storage server to make users from the storage server The content is fast, the delay is small, and good service quality can be obtained; and the same content of the storage server can be downloaded multiple times, thereby reducing the traffic of the user uploading content. However, in the prior art adopting the passive storage method, the information transfer of the storage server is slow, and the storage server cannot be fully utilized. As shown in Figure 1, the content distribution node (peer) requests content from other peers without knowing which peers own the storage server. If the requested peer does not have a storage server for the peer, it can only obtain from the requested peer. Content, but can not get content from the storage server of other peer peers, which is not conducive to improving the quality of service, which is also not conducive to reducing the upload traffic of the requested peer. It can be seen that the prior art cannot fully utilize the storage server to reduce traffic and improve service quality. Summary of the invention

In view of this, the main object of the present invention is to provide a method and system for P2P content distribution to fully utilize a storage server to reduce traffic and improve service quality.

In order to achieve the above object, the technical solution of the present invention is achieved as follows:

The present invention provides a method for P2P content distribution, the method comprising:

The tracking server records the address of the distribution node having the content/content fragment or the content/content fragment distribution, and records the storage server address where the content/content fragment is located;

The second content distribution node queries the tracking server for a list of nodes that own the specified content/content segment, or participates in the specified content/content segment distribution, and the tracking server returns a corresponding node list to the second content distribution node, in the node list At least an address of the first storage server that the first content distribution node uploads the content/content fragment;

The second content distribution node downloads the specified content/content fragment directly from the first storage server in the node list, or indirectly downloads the specified content from the first storage server in the node list via the second storage server Content fragment.

The tracking server records an address of a content distribution node having a content/content fragment or participating in content/content fragment distribution, and records a storage server address where the content/content fragment is located, Specifically:

The first content distribution node uploads the content/content fragment to the first storage server;

The first storage server stores the received content/content fragment;

The first content distribution node reports the first storage server address to the tracking server, and the content/content fragments it possesses;

The tracking server records the first storage server address and the content/content fragments it owns. The tracking server records an address of the content distribution node that owns the content/content fragment or participates in the distribution of the content/content fragment, and records the storage server address where the content/content fragment is located, specifically:

The tracking server requests the first content distribution node to upload the specified content/content fragment to the first storage server;

The first content distribution node uploads the specified content/content fragment to the first storage server; the first storage server stores the received content/content fragment;

The first content distribution node reports to the tracking server that the specified content/content fragment has been successfully uploaded to the first storage server;

The tracking server records that the first storage server has the corresponding content/content fragment.

The tracking server records an address of the content distribution node that owns the content/content fragment or participates in the distribution of the content/content fragment, and records the storage server address where the content/content fragment is located, specifically:

The tracking server requires the first storage server to obtain the specified content/content fragment from the first content distribution node;

The first storage server requests a corresponding content/content fragment from the first content distribution node; the first content distribution node uploads the corresponding content/content fragment to the first storage server; the first storage server stores the received content/content fragment, The tracking server reports that the specified content/content fragment has been successfully obtained; The tracking server records that the first storage server has the corresponding content/content fragment.

The list of nodes returned by the tracking server to the second content distribution node further includes an address of the content distribution node having the specified content/content fragment, or participating in the specified content/content fragment distribution.

The present invention also provides a system for P2P content distribution, the system comprising: a tracking server, a first content distribution node, a second content distribution node, a first storage server, and a second storage server, wherein

The tracking server is configured to record an address of a content distribution node that owns content/content fragments, or participate in content/content fragment distribution, and records a storage server address where the content/content fragment is located; and is also used to provide a content distribution node Query service;

The second content distribution node is configured to query the tracking server for a node list that has a specified content/content segment, or participates in a specified content/content segment distribution, and the corresponding list returned by the tracking server includes at least a first content distribution. The node uploads the address of the first storage server of the content/content fragment; and is further configured to download the specified content/content fragment directly from the first storage server in the node list, or indirectly from the node list via the second storage server The first storage server in the downloading the specified content/content fragment;

The first content distribution node is configured to upload a content/content fragment owned by the first content distribution server to the first storage server;

The first storage server is configured to provide a second content distribution node with a direct download or an indirect download service of the specified content/content segment;

The second storage server is configured to, in the indirect download service, forward the specified content/content segment downloaded from the first storage server to the second content distribution node.

The first content distribution section is further configured to report the first storage server address and the content/content fragment owned by the tracking server to the tracking server after uploading the content/content fragment to the first storage server;

Correspondingly, the tracking server records the first storage server address, and the content it owns/inside Rong pieces.

The tracking server is further configured to: ask the first content distribution node to upload the specified content/content fragment to the first storage server;

Correspondingly, after uploading the content/content fragment to the first storage server, the first content distribution node reports to the tracking server that the specified content/content fragment has been successfully uploaded to the first storage server; the tracking server records that the first storage server owns The corresponding content/content fragment.

The tracking server is further configured to: ask the first storage server to obtain the specified content/content segment from the first content distribution node;

Correspondingly, after acquiring the specified content/content segment and storing the first storage server, reporting to the tracking server that the specified content/content segment has been successfully obtained; the tracking server records that the first storage server has the corresponding content/content segment .

The present invention provides a method and system for P2P content distribution, so that a content distribution node can quickly locate a storage server having a desired content, and thus the present invention is compared with a P2P content distribution method and system using an existing storage server. Take advantage of storage servers to better reduce traffic and improve service quality. DRAWINGS

1 is a schematic structural diagram of a P2P content distribution system using a storage server in the prior art; FIG. 2 is a schematic diagram of a P2P content distribution system using a storage server according to the present invention; FIG. 3 is a P2P content distribution method according to the present invention; Flow chart

4 is a flowchart of obtaining a content/content fragment by a storage server and tracking a content/content fragment obtained by a storage server by the storage server according to an embodiment of the present invention;

5 is a flowchart of another storage server obtaining content/content fragments and tracking content and content fragments obtained by the storage server according to an embodiment of the present invention; FIG. 6 is a flowchart of still obtaining a content/content fragment by a storage server, and tracking a content/content fragment obtained by the storage server by the storage server according to an embodiment of the present invention; FIG.

7 is a flowchart of downloading content/content fragments directly from a first storage server by a second content distribution node according to an embodiment of the present invention;

Figure 8 is a flow diagram of a second content distribution node indirectly downloading content/content fragments from a first storage server in accordance with an embodiment of the present invention. detailed description

The technical solutions of the present invention are further elaborated below in conjunction with the accompanying drawings and specific embodiments. The P2P content distribution system utilizing the storage server in the present invention comprises: at least one tracking server, at least two content distribution nodes (peers), and at least one storage server.

The tracking server is configured to record a peer address that has or may have a content/("/" representation or) piece of content, and records a storage server address where the content/content fragment is located; the tracking server may also record a certificate required to access the storage server. Right information. In addition, the tracking server is also used by the content distribution node to query a download list that provides or may provide a content/content snippet containing at least the address of the storage server that can provide the content/content snippet.

A content distribution node for uploading and/or downloading content; a content distribution node can upload only content, or only download content, or both upload content and download content. The content distribution node can upload content/content fragments to the storage server, or download content/content fragments from the storage server; the content/content fragments can also be directly passed between the peers.

A storage server for uploading and downloading content for the content distribution node. The storage server does not support the P2P protocol.

The storage server can be provided directly to the content distribution node by the storage service provider. In this case, the content distribution node grasps the information of the storage server it uses (including the address of the storage server, and may also include other information such as the authentication information of the storage server), and can provide the information of the storage server to the tracking server. And other content distribution nodes for other content The distribution node accesses its storage server.

The storage server may also be provided by the storage service provider to the content distribution application provider and then provided to the content distribution node by the content distribution application provider. In this case, the tracking server grasps the information of the storage server it uses (including the address of the storage server, and may also include other information such as the authentication information of the storage server), and can provide the information of the storage server to the content distribution node. , so that the content distribution node accesses its storage server. The storage service provider and the content distribution application provider can be integrated.

It should be noted that the download list described in the present invention includes at least an address of a storage server capable of providing a content/content fragment; if the access of the storage server requires authentication, it also needs to include a reference required to access the storage server. Right information. Additionally, the download list may also include an address of a content distribution node that can provide or may provide content/content segments. A content distribution node that may provide content/content fragments refers to a content distribution node that participates in the distribution of corresponding content/content fragments. When the download list includes both the address of the storage server that can provide the content/content fragment and the address of the content distribution node that can provide or may provide the content/content fragment, the content distribution node that requests the download preferentially selects The storage server that provides the content/content fragment requests downloading, which ensures that the content distribution node downloads the required content/content fragments from the storage server as much as possible, and minimizes the operation of downloading the content/content fragments directly from the content distribution node, thereby facilitating the operation. Make full use of the storage server, thereby reducing the upload traffic of the requested content distribution node and improving the quality of service.

In addition, in the case that the download list includes a content distribution node capable of providing content/content fragments, the content distribution node needs to notify the tracking server when the locally stored content/content fragment increases or decreases, and the tracking server records ;

For the case where the download list contains a content distribution node that may provide a content/content fragment, the content distribution node does not need to report to the tracking server what content/content fragment is stored locally, and only needs to report to the tracking server to join the certain Distribution of content/content fragments (reporting) The content distribution node may or may not have the content/content snippet. The content distribution node can only obtain a download list from the tracking server that may have the content/content snippet. Typically, the content distribution node obtains a download list from the tracking server that may have content (may be completely free of content, may have partial content, or may have all content), and the content distribution node selects a content distribution node from the download list to ask the other party to own After the content is fragmented, request the content piece that you want and that the other party owns.

In addition, the content distribution node may request the entire content/content fragment, or just a part of the content/content fragment, to a certain storage server or content distribution node, that is, the granularity of the data request is less than or equal to the granularity of the data location.

A P2P content distribution system architecture using a storage server is provided in the embodiment of the present invention. As shown in FIG. 2, the architecture includes: a tracking server, a first content distribution node, and a first storage server for uploading content/content fragments. And a second content distribution node and a second storage server. Wherein, the second content distribution node is the party that wants to obtain the content/content fragment, and the first content distribution node is the content/content fragment side required by the second content distribution node, but those skilled in the art should understand that in practical applications Any one of the content distribution nodes may have both the function of the first content distribution node and the function of the second content distribution node. In addition, the content can be movies, music, text, pictures, etc.; a piece of content is part of a complete piece of content, such as a movie, a section of a song.

Combined with the system architecture shown in FIG. 2, the P2P content distribution method using the storage server is as shown in FIG. 3, and mainly includes the following steps:

Step 301: The tracking server records the address of the content distribution node that owns the content/content fragment, or participates in the content/content fragment distribution, and records the storage server address where the content/content fragment is located.

Step 302: The second content distribution node queries the tracking server for the node list that owns the specified content/content segment, or participates in the specified content/content segment distribution, and the tracking server returns a corresponding node list to the second content distribution node, where the node list is at least The address of the first storage server containing the content/content fragment uploaded by the first content distribution node. Step 303: The second content distribution node directly downloads the specified content/content segment from the first storage server in the node list, or indirectly downloads the specified content/content segment from the first storage server in the node list via the second storage server. Specific operations regarding direct download or indirect download will be described in detail in the following embodiments.

An embodiment of the present invention provides a storage system architecture using a storage server. As shown in FIG. 2, the architecture includes: a tracking server, a first content distribution node, and a first storage server for uploading content/content fragments. And a second content distribution node and a second storage server. Wherein, the second content distribution node is the party that wants to obtain the content/content fragment, and the first content distribution node is the content/content fragment side required by the second content distribution node, but those skilled in the art should understand that in practical applications Any one of the content distribution nodes may have both the function of the first content distribution node and the function of the second content distribution node. In addition, the content can be movies, music, text, pictures, etc.; a piece of content is part of a complete piece of content, such as a movie, a section of a song. As shown in FIG. 4, in a embodiment of the present invention, a storage server obtains a content/content fragment and a process of tracking a server to record a content/content fragment obtained by the storage server, which mainly includes the following steps:

Step 401: The first content distribution node uploads the content/content fragment to the first storage server. The upload is determined autonomously by the first content distribution node. In this case, the first storage server is generally provided by the storage service provider for use by the first content distribution node, and the first content distribution node has information of the first storage server (including the address of the first storage server, and may also include Other information such as authentication information of the first storage server).

Step 402: The first storage server stores the received content/content fragment.

Step 403: The first storage server returns an upload success response to the first content distribution node. Step 404: The first content distribution node reports the first storage server address to the tracking server. And report the content/content fragment owned by the first storage server.

The first content distribution node may also report to the tracking server the authentication information required to access the first storage server.

Step 405: The tracking server records the first storage server address, and records the content/content fragment owned by the storage server.

The tracking server may also record the authentication information required to access the first storage server.

Step 406: The tracking server returns a report success response to the first content distribution node.

As shown in FIG. 5, in another embodiment of the present invention, another storage server obtains a content/content fragment, and a tracking server records the content/content fragment obtained by the storage server, which mainly includes the following steps:

Step 501: The tracking server requests the first content distribution node to upload the specified content/content fragment to the first storage server.

The content/content fragment upload is determined by the tracking server. In this case, the general storage server is provided by the storage service provider to the content distribution application provider and then provided to the content distribution node by the content distribution application provider.

Step 502: The first content distribution node uploads the content/content fragment to the first storage server. Step 503: The first storage server stores the received content/content fragment.

Step 504: The first storage server returns an upload success response to the first content distribution node. Step 505: The first content distribution node reports to the tracking server that the specified content/content fragment has been successfully uploaded to the first storage server.

Step 506: The tracking server records that the first storage server has a corresponding content/content fragment.

As shown in FIG. 6, in another embodiment of the present invention, a storage server obtains a content/content fragment, and a tracking server records a content/content fragment obtained by the storage server, and the method includes the following steps: Step 601: The tracking server requests the first storage server to acquire the specified content/content segment from the first content distribution node.

Content/content fragment acquisition is determined by the tracking server. In this case, the general storage server is provided by the storage service provider to the content distribution application provider and then provided to the content distribution node by the content distribution application provider.

Step 602: The first storage server requests a corresponding content/content fragment from the first content distribution node.

Step 603: The first content distribution node uploads the corresponding content/content fragment to the first storage server.

Step 604, the first storage server stores the received content/content fragment.

Step 605: The first storage server reports to the tracking server that the specified content/content fragment has been successfully obtained.

Step 606: The tracking server records that the first storage server has a corresponding content/content fragment.

As shown in FIG. 7, in the P2P content distribution process shown in FIG. 3, the second content distribution node obtains the first storage obtained server information, and directly downloads the content/content fragment from the first storage server, specifically including the following steps. :

Step 701: The second content distribution node queries the tracking server for a download list of the specified content/content segment.

Step 702: The tracking server returns a download list including the first storage server to the second content distribution node.

The download list contains the address of the first storage server that can provide the content/content fragment; if the access of the first storage server requires authentication, it also needs to include the authentication information required to access the first storage server.

In addition, the download list may also contain other storage services that provide the content/content fragment. The content distribution node may also include a content distribution node that can provide or may provide the content/content fragment. Step 703: The second content distribution node requests the content/content segment from the first storage server. Step 704: The first storage server returns the content/content fragment to the second content distribution node. As shown in FIG. 8, in the P2P content distribution process shown in FIG. 3, the second content distribution node obtains the first storage server information, and indirectly downloads the content/content fragment from the first storage server via the second storage server. Specifically, the following steps are included:

Step 801: The second content distribution node queries the tracking server for a download list of the specified content/content segment.

Step 802: The tracking server returns a download list including the first storage server to the second content distribution node.

In addition, the download list may also contain other storage servers that provide the content/content snippets, and may also include content distribution nodes that provide or may provide the content/content snippets.

Step 803: The second content distribution node requests the second storage server to download the content/content fragment from the first storage server.

In this case, the second content distribution node needs to predict the address of the second storage server; if accessing the second storage server requires authentication, the second content distribution node also needs to predict the authentication information required to access the second storage server. In the scenario of indirect acquisition of content/content fragments, the second storage server is typically provided by the storage server provider for use by the second content distribution node, typically the second storage server is off the second content distribution node network than the first storage server The distance is close.

In the request message, the second content distribution node provides the address of the first storage server to the second storage server; if the access of the first storage server requires authentication, it should also include the authentication information required to access the first storage server. . Step 804: The second storage server requests the content/content segment from the first storage server. Step 805: The first storage server returns the content/content fragment to the second storage server. Step 806: The second storage server stores the content/content segment.

The content/content fragment stored by the second storage server can be provided to a plurality of content distribution nodes including the first content distribution node.

Step 807: The second storage server returns the content/content fragment to the second content distribution node. Step 808: The second content distribution node reports the address of the second storage server to the tracking server, and reports the content/content fragment owned by the second storage server.

The second content distribution node may also report to the tracking server the authentication information required to access the second storage server.

Step 809, the tracking server records the second storage server address, and records the content/content fragment owned by the second storage server.

The tracking server may also record the authentication information required to access the second storage server.

Step 810: The tracking server returns a report success response to the second content distribution node.

It should be noted that, after the step 807 is completed, the second content distribution node has obtained the requested content/content fragment. Steps 808-810 are optional steps by which the tracking server learns that the second storage server stores the content/content fragment.

Although in the specific embodiment shown in FIG. 3 to FIG. 8, the second content distribution node is the party that wants to obtain the content/content fragment, the first content distribution node is the content/content fragment side required to have the second content distribution node. For example, the person skilled in the art should understand that the technical solution described in this specific embodiment is also applicable to other nodes in the P2P content distribution system that are in the same position.

The above is only the preferred embodiment of the present invention and is not intended to limit the scope of the present invention.

Claims

Claim

A method for point-to-point P2P content distribution, the method comprising:

The tracking server records an address of the content distribution node that owns the content/content piece, or participates in the distribution of the content/content piece, and records the storage server address where the content/content piece is located; the second content distribution node queries the tracking server for the ownership designation a content/content fragment, or a list of nodes participating in the distribution of the specified content/content fragment, the tracking server returning a corresponding node list to the second content distribution node, the node list including at least the content uploading content/content fragment of the first content distribution node The address of the first storage server;

2. The method of P2P content distribution according to claim 1, wherein the tracking server records an address of a content distribution piece that owns a content/content piece, or participates in content/content piece distribution, and records the content/content piece where Storage server address, specifically:

The first storage server stores the received content/content fragment;

The first content distribution node reports the first storage server address to the tracking server, and the content/content fragment it owns;

The tracking server records the first storage server address and the content/content fragments it owns.

3. The method of P2P content distribution according to claim 1, wherein said tracking server records an address of a content distribution piece that owns content/content pieces, or participates in content/content piece distribution, and records the content/content piece where Storage server address, specifically:

4. The method of P2P content distribution according to claim 1, wherein the tracking server records an address of a content distribution piece that owns a content/content piece, or participates in content/content piece distribution, and records the content/content piece where Storage server address, specifically:

The tracking server requests the first storage server to obtain the specified content/content fragment from the first content distribution node;

The first storage server requests a corresponding content/content fragment from the first content distribution node; the first content distribution node uploads the corresponding content/content fragment to the first storage server; the first storage server stores the received content/content fragment, The tracking server reports that the specified content/content fragment has been successfully obtained;

The method for distributing P2P content according to any one of claims 1 to 4, wherein the node list returned by the tracking server to the second content distribution node further includes owning the specified content/content segment, or participating in the specified content/ The address of the content distribution node to which the content fragment is distributed.

A system for peer-to-peer P2P content distribution, the system comprising: a tracking server, a first content distribution node, a second content distribution node, a first storage server, and a second storage server, wherein

The second content distribution node is configured to query the tracking server for a node list that has a specified content/content segment, or participates in a specified content/content segment distribution, the tracking server Returning the corresponding list at least the address of the first storage server of the first content distribution node uploading content/content fragment; also for downloading the specified content/content fragment directly from the first storage server in the node list, or Downloading the specified content/content segment from the first storage server in the node list indirectly via the second storage server;

The P2P content distribution system according to claim 6, wherein the first content distribution section is further configured to report the first storage server address to the tracking server after uploading the content/content fragment to the first storage server, And the content/content fragments it owns;

Correspondingly, the tracking server records the first storage server address and the content/content fragments it owns.

The P2P content distribution system according to claim 6, wherein the tracking server is further configured to: ask the first content distribution node to upload the specified content/content fragment to the first storage server;

The P2P content distribution system according to claim 6, wherein the tracking server is further configured to: ask the first storage server to acquire the specified content/content segment from the first content distribution node;

Correspondingly, after the first storage server obtains the specified content/content fragment and stores it, Reporting to the tracking server that the specified content/content fragment has been successfully obtained; the tracking server records that the first storage server has the corresponding content/content fragment.

The P2P content distribution system according to any one of claims 6 to 9, wherein the tracking server returns the node list returned to the second content distribution node, further comprising owning the specified content/content segment, or participating in the specified content/ The address of the content distribution node to which the content fragment is distributed.