CDNs with DASH and iDASH Using Priority Caching

Abstract

Global Internet traffic shows an upward trend mainly driven by the increasing demand for video services. In addition the further spread of mobile Internet leads to an increased diversification of access data rates and internet terminals. In such a context, Content Delivery Networks (CDNs) are forced to offer content in multiple versions for different resolutions. Moreover multiple bitrates are needed, such that emerging adaptive streaming technologies are enabled to adapt to network congestion. This enormous proliferation of the multimedia content becomes more and more a challenge for the efficiency of existing network and caching infrastructure. Dynamic Adaptive Streaming over HTTP (DASH) is an emerging standard which enables adaptation of the media bitrate to varying throughput conditions by offering multiple representations of the same content. The combination of Scalable Video Coding (SVC) with DASH, called improved DASH (iDASH) consists basically of relying on SVC to provide the different representations. This paper shows how prioritized caching strategies can improve the caching performance of (i)DASH services. Results obtained from statistics of a real world CDN deployment and a simple revenue model show a clear benefit in revenue for content providers when priority caching is used especially in combination with iDASH.