Content Delivery Network Design Research Articles

Tapping the Knowledge of Dynamic Traffic Demands for Optimal CDN Design

The content delivery network (CDN) intensively uses cache to push the content close to end users. Over both traditional Internet architecture and emerging cloud-based framework, cache allocation has been the core problem that any CDN operator needs to address. As the first step for cache deployment, CDN operators need to discover or estimate the distribution of user requests in different geographic areas. This step results in a statistical spatial model for the user requests, which is used as the key input to solve the optimal cache deployment problem. More often than not, the temporal information in user requests is omitted to simplify the CDN design. In this paper, we disclose that the spatial request model alone may not lead to truly optimal cache deployment and revisit the problem by taking the dynamic traffic demands into consideration. Specifically, we model the time-varying traffic demands and formulate the distributed cache deployment optimization problem with an integer linear program (ILP). To solve the problem efficiently, we transform the ILP problem into a scalable form and propose a greedy diagram to tackle it. Via experiments over the North American ISPs points of presence (PoPs) network, our new solution outperforms traditional CDN design method and saves the overall delivery cost by 16% to 20%. We also study the impact of various traffic demand patterns to the CDN design cost, via experiments with both real-world traffic demand patterns and extensive synthetic trace data.

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.

Design and Deployment of Low-Delay Hybrid CDN–P2P Architecture for Live Video Streaming Over the Web

In the recent years, with the development of high-speed and broadband networking, the content delivery service has been grown up widely. There are a lot of providers for online streaming via content delivery network (CDN) and peer to peer (P2P) network, each having its own set of advantages and disadvantages. CDN provide excellent quality to end-users when the work load is within the provisioning limits. However, CDN servers are expensive to deploy and maintain. While P2P network has better scalability and less deployment costs, but the instability of dynamic peers, and the low performance when participated peers are insufficient are a bottleneck. So, by combining advantages of two system we will take advantage of both. In this paper, we propose the hybrid CDN---P2P structure for live video streaming over the Web in order to decrease the number of requests to CDN servers that means reduce the cost of transmission. Also by set up short timeout for request to server and split video into small chunk, our system has smaller end-to-end delay than unconnected mesh system in Seyyedi and Akbari (Hybrid CDN---P2P architectures for live video streaming: comparative study of connected and unconnected meshes. In: International symposium on computer networks and distributed systems, 2011). By set up a reality, we compare two metrics: the number of requests to CDN server and end-to-end delay with previous researches. Through experiment, we will show that a hybrid CDN---P2P approach is very effective approach in providing a live streaming service to the public.

YouLighter: A Cognitive Approach to Unveil YouTube CDN and Changes

YouTube relies on a massively distributed content delivery network (CDN) to stream the billions of videos in its catalog. Unfortunately, very little information about the design of such CDN is available. This, combined with the pervasiveness of YouTube, poses a big challenge for Internet service providers (ISPs), which are compelled to optimize end-users’ quality of experience (QoE) while having almost no visibility and understanding of CDN decisions. This paper presents YouLighter , an unsupervised technique that builds upon cognitive methodologies to identify changes in how the YouTube CDN serves traffic. YouLighter leverages only passive measurements and clustering algorithms to group caches that appear colocated and identical into edge-nodes. This automatically unveils the YouTube edge-nodes used by the ISP customers. Next, we leverage a new metric, called Pattern Dissimilarity , that compares the clustering results obtained from two different time snapshots to pinpoint sudden changes. By running YouLighter over 10-month long traces obtained from two ISPs in different countries, we pinpoint both sudden changes in edge-node allocation, and small alterations to the cache allocation policies, which actually impair the QoE that the end-users perceive.

Complexity Results for the Design Problem of Content Distribution Networks

Content Delivery Network (CDN) has evolved to overcome a network bottleneck and improve user perceived Quality of Service (QoS). A CDN replicates contents from the origin server to replica servers to reduce the overload of the origin server. CDN providers would try to achieve an acceptable performance at the least cost including the storage space or processing power. In this paper, we introduce a new optimization model for the CDN design problem considering the user perceived QoS and single path (non-bifurcated) routing constraints and analyze the computational complexity for some special cases.

The location-dispatching problem: Polyhedral results and content delivery network design

Let G=(V,A) be a directed graph and F be a set of items. The Location-Dispatching Problem consists of determining subsets Li⊆F located at nodes i∈V, minimizing the sum of two costs: a piecewise linear installation cost associated with Li and an access cost for each node of V to reach a copy of each item of F. We formulate this problem as a linear program with binary variables x and integer variables z. We propose a facial study of the associated polytope and we introduce the so-called integrity hop cost inequalities that force z to be an integer as soon as x is binary. Using this, we devise a branch-and-cut algorithm and report some experimental results. This algorithm has been used to solve Content Delivery Network instances in order to optimize a Video On Demand (VoD) system.

The Location-Dispatching Problem: polyhedral results and Content Delivery Network Design

Abstract Let G = ( V , A ) be a directed graph and F be a set of items. The Location-Dispatching Problem consists of determining subsets L i ⊆ F , i ∈ V , minimizing the sum of two costs: an installation cost associated with nodes i of V such that L i ≠ ∅ and an access cost to each item of F. We formulate this problem as an integer linear program and propose a facial study of the associated polytope. We describe valid inequalities and give sufficient conditions for these inequalities to be facet defining. Using this, we devise a Branch-and-Cut algorithm and report some preliminary experimental results. This algorithm has been used to solve Content Delivery Network instances in order to optimize a Video On Demand (VoD) system.