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Relay discovery and selection for large-scale P2P streaming

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.


CDF of the optimality ratio using indirect measurements.
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pone.0175360.g009: CDF of the optimality ratio using indirect measurements.

Mentions: The proposed two-phase relay selection approach is essentially a heuristic approach. In the following, we evaluate the optimality of the two-phase selection using the metric of the optimality ratio, which is defined as the ratio of the end-to-end RTT using the selected relay and the RTT using the optimal relay. The optimal relay is identified using brute force. In Fig 9, we plot the CDFs of the optimality ratio of the different relay selection methods. Around 90% of the pairs can find a relay path with at most 50% larger RTT than the optimal relay path using the two-phase methods. In addition, we observe that, the King-guided relay selection has a much better performance than ICS since the King estimations are much more accurate than ICS as we showed in previous sections. This two-phase selection has significant improvements for both the King-guided and ICS-guided algorithms. In particular, “King Opt 1” can find the optimal relay path for about 20% pairs; when using “King Opt 5”, this value increases almost to 60%, which has a 40% improvement. Nevertheless, the improvement of “Opt 5” over “Opt 1” is only about 10% for ICS.


Relay discovery and selection for large-scale P2P streaming
CDF of the optimality ratio using indirect measurements.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0175360.g009: CDF of the optimality ratio using indirect measurements.
Mentions: The proposed two-phase relay selection approach is essentially a heuristic approach. In the following, we evaluate the optimality of the two-phase selection using the metric of the optimality ratio, which is defined as the ratio of the end-to-end RTT using the selected relay and the RTT using the optimal relay. The optimal relay is identified using brute force. In Fig 9, we plot the CDFs of the optimality ratio of the different relay selection methods. Around 90% of the pairs can find a relay path with at most 50% larger RTT than the optimal relay path using the two-phase methods. In addition, we observe that, the King-guided relay selection has a much better performance than ICS since the King estimations are much more accurate than ICS as we showed in previous sections. This two-phase selection has significant improvements for both the King-guided and ICS-guided algorithms. In particular, “King Opt 1” can find the optimal relay path for about 20% pairs; when using “King Opt 5”, this value increases almost to 60%, which has a 40% improvement. Nevertheless, the improvement of “Opt 5” over “Opt 1” is only about 10% for ICS.

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.