A Survey on Content Placement Algorithms for Cloud-Based Content Delivery Networks <s> D. OTHER IMPLICATIONS 1) REQUEST REDIRECTION <s> YouTube is the most popular service in today's Internet. Google relies on its massive content delivery network (CDN) to push YouTube videos as close as possible to the end-users, both to improve their watching experience as well as to reduce the load on the core of the network, using dynamic server selection strategies. However, we show that such a dynamic approach can actually have negative effects on the end-user quality of experience (QoE). Through the comprehensive analysis of one month of YouTube flow traces collected at the network of a large European ISP, we report a real case study in which YouTube QoE-relevant degradation affecting a large number of users occurs as a result of Google's server selection strategies. We present an iterative and structured process to detect, characterize, and diagnose QoE-relevant anomalies in CDN distributed services such as YouTube. The overall process uses statistical analysis methodologies to unveil the root causes behind automatically detected problems linked to the dynamics of CDNs' server selection strategies. <s> BIB001 </s> A Survey on Content Placement Algorithms for Cloud-Based Content Delivery Networks <s> D. OTHER IMPLICATIONS 1) REQUEST REDIRECTION <s> Geographically distributed cloud platforms enable an attractive approach to large-scale content delivery. Storage at various sites can be dynamically acquired from (and released back to) the cloud ... <s> BIB002
Another research challenge is the effectiveness and cost analysis of a smarter CCDN request redirection scheme, which greatly impacts QoE BIB001 . Request redirection is aware of the surrogate servers and their content and redirects enduser requests based on load-balancing, QoS or network health metrics. This scheme can utilize neural network or reinforcement learning techniques to build a surrogate-content relationship table such that the redirection is simply a look up in the table. However, the exchange of information between the redirector and the surrogate servers incurs bandwidth and storage costs at the redirector. It is interesting to scrutinize the economic benefits of this redirector and the latency and responsiveness of this scheme. It remains a challenge to evaluate CP algorithms efficiency with BIB002 and without request redirection techniques.