Content Delivery Network Infrastructure Research Articles

Minimizing the In-Cloud Bandwidth for On-Demand Reactive and Proactive Streaming Applications

Video streaming services are one of the most resource-consuming applications on the Internet. Thus, minimizing the consumed resources at runtime in general and the server/network bandwidth in particular are still challenging for researchers. Currently, most streaming techniques used on the Internet open one stream per client request, which makes the consumed bandwidth increases linearly. Hence, many broadcasting/streaming protocols have been proposed in the literature to minimize the streaming bandwidth. These protocols can be divided into two main categories, namely, reactive and proactive broadcasting protocols. While the first category is recommended for streaming unpopular videos, the second category is recommended for streaming popular videos. In this context, in this paper we propose an enhanced version of the reactive protocol Slotted Stream Tapping (SST) called Share All SST (SASST), which we prove to further reduce the streaming bandwidth with regard to SST. We also propose a new proactive protocol named the New Optimal Proactive Protocol (NOPP) based on an optimal scheduling of video segments on streaming-channel. SASST and NOPP are to be used in cloud and CDN (content delivery network) networks where the IP multicast or multicast HTTP on QUIC could be enabled, as their key principle is to allow the sharing of ongoing streams among clients requesting the same video content. Thus, clients and servers are often services running on virtual machines or in containers belonging to the same cloud or CDN infrastructure.

Content Delivery Network Security: A Survey

A content delivery network (CDN) is a distributed infrastructure to deliver digital contents to end users with high performance. CDNs are critical to provide and protect the availability of Internet contents. However, adversaries can not only evade the CDN protection but also weaponize CDN resources to mount more sophisticated attacks. In this paper, we provide the first survey on CDN security. We categorize CDN security challenges per CDN infrastructure components, discuss possible countermeasures and their effectiveness, and delineate future research directions. This paper aims to highlight the state of CDN security and identify important research challenges in this area.

On Private CDNs with Off-Sourced Network Infrastructures: a Model and a Case Study

The delivery of multimedia contents through a Content Delivery Network (CDN) is typically handled by a specific third party, separated from the content provider. However, in some specific cases, the content provider may be interested in carrying out this function using a private CDN, possibly using a off-sourced network infrastructure. The differences between this scenario and the typical content delivery one can be summarized as follows. First, we have a different workload as the content consumer are typically part of the same organization that is the content provider. Second, the off-sourced nature of the network infrastructure has a major impact on the available choices for CDN design. In this paper we discuss the optimization model for the design of such CDN infrastructure and we validate the results through a real case study.

Application of SAND Technology in DASH-Enabled Content Delivery Networks and Server Environments

MPEG Dynamic Adaptive Streaming over HTTP (DASH) provides formats that are suitable to stream segmented media content over HTTP. DASH clients follow a client-pull paradigm by adapting their requests based on the available bandwidth and other local resources. This has proven to be easier to deploy over content delivery network infrastructure than server-push technologies. However, this decentralized nature introduces new challenges such as offering a consistent and higher quality of service for premium users. MPEG addresses this issue in the recently published MPEG-DASH part 5, Server and Network-Assisted DASH (SAND). The key features of SAND are asynchronous network-to-client and network-to-network communication of quality-related assisting information. This way, the quality of services can be improved by the DASH clients reacting realtime to the assistance and recommendation sent by the service provider. In addition, DASH-Industry Forum (DASH-IF) is further defining interoperable guidelines to optimize SAND deployments in a variety of environments: home network, over-the-top, and so on. DASH-IF is expected to publish this new interoperable guideline by the end of 2017.

Applying a rateless code in content delivery networks

Content delivery network (CDN) allows internet providers to locate their services, to map their coverage into networks without necessarily to own them. CDN is part of the current internet infrastructures, supporting multi server applications especially social media. Various works have been proposed to improve CDN performances. Since accesses on social media servers tend to be short but frequent, providing redundant to the transmitted packets to ensure lost packets not degrade the information integrity may improve service performances. This paper examines the implementation of rateless code in the CDN infrastructure. The NS-2 evaluations show that rateless code is able to reduce packet loss up to 50%.

Optimal Delivery of Rate-Adaptive Streams in Underprovisioned Networks

The growth of Internet video traffic imposes a severe capacity problem in today's Content Delivery Network (CDN). Rate-adaptive streaming technologies, such as the Dynamic Adaptive Streaming over HTTP (DASH) standard, reinforces this problem in the core CDN infrastructure since delivering one video means delivering multiple representations for an aggregated bit-rate that is commonly over 10 Mbps. In this paper, we explore better trade-offs between CDN infrastructure cost and Quality of Experience (QoE) of the end-users for live broadcast video streaming applications. We consider in particular underprovisioned CDN networks, our goal being to maximize the QoE for the population of heterogeneous end-users despite the lack of resources in the intermediate CDN equipments. We show that previous theoretical models based on elastic bit-rates do not fit for this context. We propose a user-centric discretized streaming model where the satisfaction of end-users is related to the context and where a stream has to be either delivered in its entirety, or not delivered at all. We first formulate an Integer Linear Program (ILP) that achieves the optimal delivery through a multi-tree delivery overlay. The evaluation of the ILP shows the benefits of this model. We then design a practical system by revisiting the three main algorithms implemented in CDN: user-to-server assignment, content placement and content delivery. At last, we use a realistic trace-driven large-scale simulator to study the performances of our system. In particular, we show that the population of users is reasonably well served (three quarters of the population do not experience degradation) even when the CDN infrastructure experiences a severe underprovisioning (less than half of the required infrastructure).