Optimized Selection of Streaming Servers with GeoDNS for CDN-Delivered Live Streaming

Abstract

CDNs (Content Delivery Networks) have been increasingly being employed to facilitate the delivery of live streaming. Being a standard practice, DNS is used to enable dynamic assignment of streaming servers to improve performance. GeoDNS, which provides DNS resolution by tracking the geographical locations of end-users and CDN servers, effectively redirects users to nearest CDN edge servers for traditional web-objects. However, the new application type of live streaming exposes unique characteristics and challenges that require more advanced design of GeoDNS. Unlike traditional web-objects fetching, which allows Edge Servers to cache contents and thus typically only involves edge servers for delivering contents, live streaming requires a real-time full CDN-streaming path that spans across an Ingest Server, an Origin Server and an Edge Server.Though the nearest Origin Server can be easily determined by regular GeoDNS, it may not be the optimal one from the perspectives of both CDN transit cost and the viewer's experience. In this work, we propose a livestreaming specific GeoDNS design for selecting optimal Origin Servers to serve Edge Servers, which can save transit cost for CDNs and achieve better end-viewer's experience. Named Sticky-DNS, the new design primarily aims at optimizing CDN delivery for less-popular live streams, but can also adapt to accommodate popular live streams.