KR101462353B1 - Distributed Parent Peer Selection Method for Supporting Application-Layer Multicast Services - Google Patents

Abstract

Provided is a distributed parent peer selection method, wherein a server manages only the identification information of participating peers, and the respective participating peers determine the selection of a parent peer dispersively. A peer newly participating in a session obtains, from the server, identification information for partial peers which are participating in the session. The new participating peer requests the state information of the partial peers to the server, and calculates a probability to transmit a participation request message to each peer using the received state information. The new participating peer determines a peer to which the participation request message is to be transmitted, based on the calculated probability, and transmits the participation request message to the determined peer. The peer who has received the participation request message determines a peer to which the participation request message is to be transmitted through the same step, and transmits the participation request message to the determined peer. After this process is performed predetermined times, the peer who has received the participation request message is determined as a parent peer of the new participating peer. According to the present invention, the selection of the parent peer is performed dispersively and thus communication and processing load is distributed to a plurality of peers.

Description

{Distributed Parent Peer Selection Method for Supporting Application-Layer Multicast Services}

The present invention relates to a distributed peer selection method for providing an application layer multicast service, more specifically, a server manages only the identification information of participating peers, and the selection of a parent peer is a distributed To a method for selecting an enemy parent peer.

Multicast services are attracting interest as a way to economically provide real-time video streaming services such as Internet TV. Traditionally, multicast services have been thought to be provided at the IP layer. However, current deployment strategies lack a simple, scalable mechanism to commercially support IP multicast services, so IP multicast services have been successfully deployed in a carrier-grade network It is not.

Application layer multicast that does not require special support from an overlay network is emerging as an effective method for large-scale Internet broadcasting services such as real-time media streaming. Unlike conventional network-based multicast, application-layer multicast is achieved by a session-participant end-systems, called peers, forming an overlay network on the Internet and delivering the data they receive to other peers in a unicast manner. Therefore, the amount of resources provided by the overlay network increases in proportion to the number of participating peers, so application layer multicast is excellent in scalability.

Conventional overlay networks for application layer multicast have constructed an overlay network by newly requesting data from one of existing participating peers by arbitrarily selecting one of the existing participating peers under the assumption that the characteristics of the peers are homogeneous. However, since the peers differ in communication bandwidth, data processing capability, and data storage capacity, the selection method of the peer greatly affects the utility of the application layer multicast service.

That is, in order to prevent the problem that the data reception rate of a child peer having a large capacity is limited due to a small-capacity parent peer, the peers are configured to be sorted in descending order from the multicast source according to the capacity of the peer . In addition, since the end-to-end delay and jitter increase according to the number of hops in the multi-hop communication scheme, the overlay network should be configured in a short and wide shape centered on the multicast source.

However, due to the distributed nature of application layer multicast, the peers participating in the session can not know the status information of the overlay network and lack scalability when the server dedicated to the connection between participating peers is used. In order to solve this problem, a method of constructing an overlay network based on the bandwidth of a peer has been proposed. (M. Guo, and M. Ammar, "Scalable Live Video Streaming to Cooperative Clients using TIme Shifting and Video Patching," IEEE Infocom pp. 1501-1511, Mar. 2004), (K.-W. Kwang, and DHK Tsang , "Building Heterogeneous Peer-to-Peer Networks: Protocol and Analysis," IEEE / ACM Trans . on Networking , vol. 16, no. 2, pp. 281-292, Apr. 2008)

These techniques determine the probability of becoming a parent peer depending on the capacity of the peer and the number of child peers being supported, and the session - participant peer selects the parent peer in a distributed manner according to these probabilities. However, these techniques do not take into account the distance between the peer and the multicast source, which causes problems in terms of application service delay.

In order to solve this problem, a method for limiting the diameter of the overlay network has been proposed (A. Brocco, F. Frapolli, and B. Hirsbrunner, "Bounded Diameter Overlay Construction: A Self Organized Approach," IEEE SIS'09, pp 114-121, Mar. 2009). However, after assuming the same P2P system for all peers, it suggests a method to reduce the diameter of the overlay network in terms of the number of hops, so that the peer's capacity does not reflect the actual communication environment with different capacity.

An object of the present invention is to provide a distributed peer selection method considering both the capacity difference of a peer and the number of hops between a multicast source and a hop to effectively provide an application layer multicast service. The present invention also works in a distributed manner to distribute communication and processing load to all peers and mitigates the problem that the reception ratio of the child peer is limited due to the capacity difference of the peers because the large capacity peers support the small capacity small peers And a method of selecting a distributed parent peer that can keep the diameter of the overlay network small.

In order to achieve the above object, a method of selecting a distributed parent peer according to the present invention comprises: a first step of acquiring identification information on a part of a new participating new peer participating in a session from a server; A second step of the participating peer requesting the status information of the part of the peers to the server; calculating a probability of transmitting the participation request message to each of the peers using the status information received from the server by the new participating peer; A third step of determining a peer to which the participation request message is to be transmitted from the probability and transmitting the participation request message to the determined peer; and a third step of transmitting the participation request message to the peer having received the participation request message, Determines a peer to which the join request message is to be transmitted from the calculated probability, and transmits the join request message to the determined peer A fourth step of transmitting a join request message and a step of determining a peer receiving the join request message as a parent peer of the new participating peer after performing the predetermined number of times.

Or the fourth step is a step in which the peer having received the participation request message requests the server of the status information of the peers having the identification information thereof and transmits the participation request message to each of the peers using the status information received from the server It is also possible to calculate the probability of transmission, determine a peer to transmit the participation request message from the calculated probability, and transmit the participation request message to the determined peer.

The probability of transmitting the join request message to each peer is proportional to the maximum capacity of the corresponding peer, and the probability of transmitting the participation request message for each peer may be inversely proportional to the number of hops of the multicast source and the corresponding peer. Also, the probability of sending a join request message for each peer may be inversely proportional to the number of child peers supported by that peer.

On the other hand, if the peer participating in the session leaves the overlay network, the child peers of the peer can repeat the second through fifth steps to determine a new parent peer.

According to the present invention, the communication and processing load are distributed to a plurality of peers because the selection of the parent peer is distributedly operated. In addition, since a large capacity peer supports a small number of small peers, it is possible to mitigate the problem that the reception ratio of the child peer is limited due to the capacity difference of the peer, and the diameter of the overlay network can be kept small. In addition, when selecting the parent peer, the application layer multicast service can be effectively provided since both the capacity difference of the peer and the number of hops between the multicast source are considered.

1 is a diagram illustrating an example of an overlay network for application layer multicast to explain the present invention.
FIG. 2 is a flow chart showing operations at a new participating peer for selecting a parent peer in a newly participating new participating peer in a session.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

In the following description, the number of peers that are participating in the session N, the maximum capacity of the participating peer i x _i, peer i is supported being child peer number of n _i, a multicast can hop between peer i to the source h _i of And that the participating peer maintains information on some of the peers participating in the session, that is, M neighboring peers.

A new peer participating in the overlay network must select a peer with x _i / ( n _i h _i ) as its parent peer. However, since the new participating peer can not know the information of the existing participating peers, the present invention selects the parent peer by a distributed method based on the random walk.

In FIG. 1, a peer j newly participating in a session receiving multicasting from a multicast source obtains information on M peers among N peers currently participating. A common way for a participating peer to initially acquire M peer information is to use a server such as a tracker. However, unlike the conventional method in which the server determines the parent peer selection by maintaining the state information of the participating peers such as the available bandwidth or the connection type of the participating peer, the server manages only the identification information of the participating peers, The selection of the parent peer is decentralized by each participating peer.

To this end, the new participating peer j obtains identification information for some peers, that is, M peers from the server (step S10). The new participating peer j that has obtained the identification information of the M peers requests and obtains their status information { x _i / n _i , h _i } from the server to select one of them (step S 20).

Using the received state information, the new participating peer j determines the probability p _ji to transmit the participation request message for each peer (step S30). That is, when p _i is expressed as c _i = x _i n _i , p _ji is determined as shown in Equation (1).

The new participating peer j determines the peer to which each participation request message is to be transmitted using the calculated probability (step S40). To this end, the set _{{p ji: i = 1,} ..., M} is assumed to be sorted in ascending order according to the size of the p _ji, j is the peer according to the uniform distribution U (0,1) [0,1] generate in a random number p, and sends a request to the peer i participation message (message JOIN_REQ) satisfying the following expression (2).

The peer i that has received the participation request message from the peer j according to Equation (2) uses the state information of its neighboring peers to perform the steps S20 to S40 or the state information of the peers, The next peer to receive the join request message is determined. The participation request message to the peer in the same way j is spread on the overlay network peer j and transmits the participation request message specified in the join request message forwarding number τ. After receiving the join request message, the peers decrease τ by 1, and if τ> 0, transmit the message and the peer with τ = 0 is selected as the parent peer of j .

If the participating peer k leaves the overlay network, the child peers of k select the new parent peer by the same method to maintain the multicast session.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. That is, within the scope of the present invention, all of the components may be selectively coupled to one or more of them. In addition, although all of the components may be implemented as one independent hardware, some or all of the components may be selectively combined to perform a part or all of the functions in one or a plurality of hardware. As shown in FIG. The codes and code segments constituting the computer program may be easily deduced by those skilled in the art. Such a computer program can be stored in a computer-readable storage medium, readable and executed by a computer, thereby realizing an embodiment of the present invention. The storage medium of the computer program may include a semiconductor recording medium, a magnetic recording medium, an optical recording medium, a carrier wave medium, and the like.

Furthermore, the terms "comprises", "comprising", or "having" described above mean that a component can be implanted unless otherwise specifically stated, But should be construed as including other elements.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

100 multicast source
200 Tracker Server

Claims (8)

A first step in which a new participating new participating peer acquires identification information on some peers participating in the session from a server;
A second step of the new participating peer requesting status information of the part of the peers from the server;
The new participating peer calculates the probability of transmitting the participation request message to each of the peers using the status information received from the server, determines a peer to transmit the participation request message from the calculated probability, and transmits the participation request message to the determined peer A third step of,
The peer receiving the participation request message calculates the probability of transmitting the participation request message to the peers having the status information, determines the peer to transmit the participation request message from the calculated probability, and transmits the participation request message to the determined peer A fourth step of,
Determining a peer that has received the participation request message as a parent peer of the new participating peer after performing the predetermined number of times of the fourth step
And,
When the maximum capacity of a peer i x _i, peer i is supported that is the number of hops between the own peer number of n _i, the multicast source and the peer i as h _i, and denoted as c _i = x _i / n _i, new The probability p _ji that the participating peer j will send a join request message to peer i

Lt; / RTI >
Determining a peer to which to send a join request message from the computed probability,
Generating an arbitrary number p between 0 and 1,
When the calculated probabilities are sorted in ascending order according to their sizes,

I. ≪ / RTI > A first step in which a new participating new participating peer acquires identification information on some peers participating in the session from a server;
A second step of the new participating peer requesting status information of the part of the peers from the server;
The new participating peer calculates the probability of transmitting the participation request message to each of the peers using the status information received from the server, determines a peer to transmit the participation request message from the calculated probability, and transmits the participation request message to the determined peer A third step of,
The peer receiving the participation request message requests status information of the peers having the identification information to the server, calculates the probability of transmitting the participation request message to each of the peers using the status information received from the server, A fourth step of determining a peer to which the join request message is to be transmitted, and transmitting the join request message to the determined peer,
A fifth step of determining the peer that has received the participation request message as the parent peer of the new participating peer after the fourth step is performed a predetermined number of times,
And,
When the maximum capacity of a peer i x _i, peer i is supported that is the number of hops between the own peer number of n _i, the multicast source and the peer i as h _i, and denoted as c _i = x _i / n _i, new The probability p _ji that the participating peer j will send a join request message to peer i

Lt; / RTI >
Determining a peer to which to send a join request message from the computed probability,
Generating an arbitrary number p between 0 and 1,
When the calculated probabilities are sorted in ascending order according to their sizes,

I. ≪ / RTI > delete delete delete delete delete 3. The method according to claim 1 or 2,
When the peer participating in the session leaves the overlay network, the child peers of the peer repeat the second through fifth steps to determine a new parent peer.

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