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Relay discovery and selection for large-scale P2P streaming

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ABSTRACT

In peer-to-peer networks, application relays have been commonly used to provide various networking services. The service performance often improves significantly if a relay is selected appropriately based on its network location. In this paper, we studied the location-aware relay discovery and selection problem for large-scale P2P streaming networks. In these large-scale and dynamic overlays, it incurs significant communication and computation cost to discover a sufficiently large relay candidate set and further to select one relay with good performance. The network location can be measured directly or indirectly with the tradeoffs between timeliness, overhead and accuracy. Based on a measurement study and the associated error analysis, we demonstrate that indirect measurements, such as King and Internet Coordinate Systems (ICS), can only achieve a coarse estimation of peers’ network location and those methods based on pure indirect measurements cannot lead to a good relay selection. We also demonstrate that there exists significant error amplification of the commonly used “best-out-of-K” selection methodology using three RTT data sets publicly available. We propose a two-phase approach to achieve efficient relay discovery and accurate relay selection. Indirect measurements are used to narrow down a small number of high-quality relay candidates and the final relay selection is refined based on direct probing. This two-phase approach enjoys an efficient implementation using the Distributed-Hash-Table (DHT). When the DHT is constructed, the node keys carry the location information and they are generated scalably using indirect measurements, such as the ICS coordinates. The relay discovery is achieved efficiently utilizing the DHT-based search. We evaluated various aspects of this DHT-based approach, including the DHT indexing procedure, key generation under peer churn and message costs.

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Performance comparison between different relay selection methods.
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pone.0175360.g002: Performance comparison between different relay selection methods.

Mentions: To evaluate the delay performance using a relay for one peer pair, we define RTT comparison ratio as the ratio between the total end-to-end RTT via the selected relay to the direct RTT. Fig 2 shows the Cumulative Distribution Function (CDF) of the RTT comparison ratio. Note that when this ratio equals 1, the peer pair does not achieve any benefit to decrease the RTT using a relay. The “brute force” method serves as a benchmark of the optimal relay selection in that all the relay candidates are examined and the one is selected which has the minimal end-to-end RTT for a peer pair using this relay.


Relay discovery and selection for large-scale P2P streaming
Performance comparison between different relay selection methods.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5391927&req=5

pone.0175360.g002: Performance comparison between different relay selection methods.
Mentions: To evaluate the delay performance using a relay for one peer pair, we define RTT comparison ratio as the ratio between the total end-to-end RTT via the selected relay to the direct RTT. Fig 2 shows the Cumulative Distribution Function (CDF) of the RTT comparison ratio. Note that when this ratio equals 1, the peer pair does not achieve any benefit to decrease the RTT using a relay. The “brute force” method serves as a benchmark of the optimal relay selection in that all the relay candidates are examined and the one is selected which has the minimal end-to-end RTT for a peer pair using this relay.

View Article: PubMed Central - PubMed

ABSTRACT

In peer-to-peer networks, application relays have been commonly used to provide various networking services. The service performance often improves significantly if a relay is selected appropriately based on its network location. In this paper, we studied the location-aware relay discovery and selection problem for large-scale P2P streaming networks. In these large-scale and dynamic overlays, it incurs significant communication and computation cost to discover a sufficiently large relay candidate set and further to select one relay with good performance. The network location can be measured directly or indirectly with the tradeoffs between timeliness, overhead and accuracy. Based on a measurement study and the associated error analysis, we demonstrate that indirect measurements, such as King and Internet Coordinate Systems (ICS), can only achieve a coarse estimation of peers’ network location and those methods based on pure indirect measurements cannot lead to a good relay selection. We also demonstrate that there exists significant error amplification of the commonly used “best-out-of-K” selection methodology using three RTT data sets publicly available. We propose a two-phase approach to achieve efficient relay discovery and accurate relay selection. Indirect measurements are used to narrow down a small number of high-quality relay candidates and the final relay selection is refined based on direct probing. This two-phase approach enjoys an efficient implementation using the Distributed-Hash-Table (DHT). When the DHT is constructed, the node keys carry the location information and they are generated scalably using indirect measurements, such as the ICS coordinates. The relay discovery is achieved efficiently utilizing the DHT-based search. We evaluated various aspects of this DHT-based approach, including the DHT indexing procedure, key generation under peer churn and message costs.

No MeSH data available.