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SmoothCache: HTTP-live streaming goes peer-to-peer
KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS.
KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS.ORCID iD: 0000-0002-6718-0144
2012 (English)In: Networking 2012, Springer Berlin/Heidelberg, 2012, Vol. 7290 LNCS, no PART 2, 29-43 p.Conference paper (Refereed)
Abstract [en]

In this paper, we present SmoothCache, a peer-to-peer live video streaming (P2PLS) system. The novelty of SmoothCache is threefold: i) It is the first P2PLS system that is built to support the relatively-new approach of using HTTP as the transport protocol for live content, ii) The system supports both single and multi-bitrate streaming modes of operation, and iii) In Smoothcache, we make use of recent advances in application-layer dynamic congestion control to manage priorities of transfers according to their urgency. We start by explaining why the HTTP live streaming semantics render many of the existing assumptions used in P2PLS protocols obsolete. Afterwards, we present our design starting with a baseline P2P caching model. We, then, show a number of optimizations related to aspects such as neighborhood management, uploader selection and proactive caching. Finally, we present our evaluation conducted on a real yet instrumented test network. Our results show that we can achieve substantial traffic savings on the source of the stream without major degradation in user experience.

Place, publisher, year, edition, pages
Springer Berlin/Heidelberg, 2012. Vol. 7290 LNCS, no PART 2, 29-43 p.
, Lecture Notes in Computer Science, ISSN 0302-9743 ; 7290
Keyword [en]
caching, CDN, HTTP-Live streaming, peer-to-peer
National Category
Computer and Information Science
URN: urn:nbn:se:kth:diva-99907DOI: 10.1007/978-3-642-30054-7_3ScopusID: 2-s2.0-84861653146ISBN: 978-364230053-0OAI: diva2:543418
11th International IFIP TC 6 Networking Conference, NETWORKING 2012; Prague; 21 May 2012 through 25 May 2012
Swedish e‐Science Research CenterICT - The Next Generation

QC 20120808

Available from: 2012-08-08 Created: 2012-08-02 Last updated: 2013-11-22Bibliographically approved
In thesis
1. A System, Tools and Algorithms for Adaptive HTTP-live Streaming on Peer-to-peer Overlays
Open this publication in new window or tab >>A System, Tools and Algorithms for Adaptive HTTP-live Streaming on Peer-to-peer Overlays
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In recent years, adaptive HTTP streaming protocols have become the de facto standard in the industry for the distribution of live and video-on-demand content over the Internet. In this thesis, we solve the problem of distributing adaptive HTTP live video streams to a large number of viewers using peer-to-peer (P2P) overlays. We do so by assuming that our solution must deliver a level of quality of user experience which is the same as a CDN while trying to minimize the load on the content provider’s infrastructure. Besides that, in the design of our solution, we take into consideration the realities of the HTTP streaming protocols, such as the pull-based approach and adaptive bitrate switching.

The result of this work is a system which we call SmoothCache that provides CDN-quality adaptive HTTP live streaming utilizing P2P algorithms. Our experiments on a real network of thousands of consumer machines show that, besides meeting the the CDN-quality constraints, SmoothCache is able to consistently deliver up to 96% savings towards the source of the stream in a single bitrate scenario and 94% in a multi-bitrate scenario. In addition, we have conducted a number of pilot deployments in the setting of large enterprises with the same system, albeit tailored to private networks. Results with thousands of real viewers show that our platform provides an average offloading of bottlenecks in the private network of 91.5%.

These achievements were made possible by advancements in multiple research areas that are also presented in this thesis. Each one of the contributions is novel with respect to the state of the art and can be applied outside of the context of our application. However, in our system they serve the purposes described below.

We built a component-based event-driven framework to facilitate the development of our live streaming application. The framework allows for running the same code both in simulation and in real deployment. In order to obtain scalability of simulations and accuracy, we designed a novel flow-based bandwidth emulation model.

In order to deploy our application on real networks, we have developed a network library which has the novel feature of providing on-the-fly prioritization of transfers. The library is layered over the UDP protocol and supports NAT Traversal techniques. As part of this thesis, we have also improved on the state of the art of NAT Traversal techniques resulting in higher probability of direct connectivity between peers on the Internet.

Because of the presence of NATs on the Internet, discovery of new peers and collection of statistics on the overlay through peer sampling is problematic. Therefore, we created a peer sampling service which is NAT-aware and provides one order of magnitude fresher samples than existing peer sampling protocols.

Finally, we designed SmoothCache as a peer-assisted live streaming system based on a distributed caching abstraction. In SmoothCache, peers retrieve video fragments from the P2P overlay as quickly as possible or fall back to the source of the stream to keep the timeliness of the delivery. In order to produce savings, the caching system strives to fill up the local cache of the peers ahead of playback by prefetching content. Fragments are efficiently distributed by a self-organizing overlay network that takes into account many factors such as upload bandwidth capacity, connectivity constraints, performance history and the currently being watched bitrate.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. xix, 41 p.
TRITA-ICT-ECS AVH, ISSN 1653-6363 ; 13:18
peer-to-peer, distributed caching, nat traversal, congestion control, adaptive HTTP streaming, live streaming
National Category
Computer Science
Research subject
urn:nbn:se:kth:diva-134351 (URN)978-91-7501-915-4 (ISBN)
Public defence
2013-12-12, Sal D, Forum, KTH-ICT, Isafjordsgatan 39, Stockholm, 13:00 (English)

QC 20131122

Available from: 2013-11-22 Created: 2013-11-21 Last updated: 2016-01-21Bibliographically approved

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