121 research outputs found
Reliable downloading algorithms for bittorrent-like systems
In this paper we study a reliable downloading algorithm for BitTorrent-like systems, and attest it in mathematics. BitTorrent-like systems have become immensely popular peer-to-peer file distribution tools in the internet in recent years. We analyze them in theory and point out some of their limitations especially in reliability, and propose an algorithm to resolve these problems by using the redundant copies in neighbors in P2P networks and can further optimize the downloading speed in some condition. Our preliminary simulations show that the proposed reliable algorithm works well; the improved BitTorrent-like systems are very stable and reliable.<br /
Improving BitTorrent's Peer Selection For Multimedia Content On-Demand Delivery
The great efficiency achieved by the BitTorrent protocol for the distribution
of large amounts of data inspired its adoption to provide multimedia content
on-demand delivery over the Internet. As it is not designed for this purpose,
some adjustments have been proposed in order to meet the related QoS
requirements like low startup delay and smooth playback continuity.
Accordingly, this paper introduces a BitTorrent-like proposal named as
Quota-Based Peer Selection (QBPS). This proposal is mainly based on the
adaptation of the original peer-selection policy of the BitTorrent protocol.
Its validation is achieved by means of simulations and competitive analysis.
The final results show that QBPS outperforms other recent proposals of the
literature. For instance, it achieves a throughput optimization of up to 48.0%
in low-provision capacity scenarios where users are very interactive.Comment: International Journal of Computer Networks & Communications(IJCNC)
Vol.7, No.6, November 201
Modeling and Control of Rare Segments in BitTorrent with Epidemic Dynamics
Despite its existing incentives for leecher cooperation, BitTorrent file
sharing fundamentally relies on the presence of seeder peers. Seeder peers
essentially operate outside the BitTorrent incentives, with two caveats: slow
downlinks lead to increased numbers of "temporary" seeders (who left their
console, but will terminate their seeder role when they return), and the
copyright liability boon that file segmentation offers for permanent seeders.
Using a simple epidemic model for a two-segment BitTorrent swarm, we focus on
the BitTorrent rule to disseminate the (locally) rarest segments first. With
our model, we show that the rarest-segment first rule minimizes transition time
to seeder (complete file acquisition) and equalizes the segment populations in
steady-state. We discuss how alternative dissemination rules may {\em
beneficially increase} file acquisition times causing leechers to remain in the
system longer (particularly as temporary seeders). The result is that leechers
are further enticed to cooperate. This eliminates the threat of extinction of
rare segments which is prevented by the needed presence of permanent seeders.
Our model allows us to study the corresponding trade-offs between performance
improvement, load on permanent seeders, and content availability, which we
leave for future work. Finally, interpreting the two-segment model as one
involving a rare segment and a "lumped" segment representing the rest, we study
a model that jointly considers control of rare segments and different uplinks
causing "choking," where high-uplink peers will not engage in certain
transactions with low-uplink peers.Comment: 18 pages, 6 figures, A shorter version of this paper that did not
include the N-segment lumped model was presented in May 2011 at IEEE ICC,
Kyot
Swarming Overlay Construction Strategies
Swarming peer-to-peer systems play an increasingly instrumental role in
Internet content distribution. It is therefore important to better understand
how these systems behave in practice. Recent research efforts have looked at
various protocol parameters and have measured how they affect system
performance and robustness. However, the importance of the strategy based on
which peers establish connections has been largely overlooked. This work
utilizes extensive simulations to examine the default overlay construction
strategy in BitTorrent systems. Based on the results, we identify a critical
parameter, the maximum allowable number of outgoing connections at each peer,
and evaluate its impact on the robustness of the generated overlay. We find
that there is no single optimal value for this parameter using the default
strategy. We then propose an alternative strategy that allows certain new peer
connection requests to replace existing connections. Further experiments with
the new strategy demonstrate that it outperforms the default one for all
considered metrics by creating an overlay more robust to churn. Additionally,
our proposed strategy exhibits optimal behavior for a well-defined value of the
maximum number of outgoing connections, thereby removing the need to set this
parameter in an ad-hoc manner
Size Does Matter (in P2P Live Streaming)
Optimal dissemination schemes have previously been studied for peer-to-peer
live streaming applications. Live streaming being a delay-sensitive
application, fine tuning of dissemination parameters is crucial. In this
report, we investigate optimal sizing of chunks, the units of data exchange,
and probe sets, the number peers a given node probes before transmitting
chunks. Chunk size can have significant impact on diffusion rate (chunk miss
ratio), diffusion delay, and overhead. The size of the probe set can also
affect these metrics, primarily through the choices available for chunk
dissemination. We perform extensive simulations on the so-called random-peer,
latest-useful dissemination scheme. Our results show that size does matter,
with the optimal size being not too small in both cases
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