Abstract
Along with the continuing evolution of the Internet and its applications, Content Delivery Networks (CDNs) have become a hot topic with both opportunities and challenges. CDNs were mainly proposed to solve content availability and download time issues by delivering content through edge cache servers deployed around the world. In our previous work, we presented a novel CDN architecture based on a Fog computing environment as a promising solution for real-time applications. In such architecture, we proposed to use a name-based routing protocol following the Information Centric Networking (ICN) approach, with a popularity-based caching strategy to guarantee overall delivery performance. To validate our design principle, we have implemented the proposed Fog-based CDN architecture with its major protocol components and evaluated its performance, as shown through this article. On the one hand, we have extended the Optimized Link-State Routing (OLSR) protocol to be content aware (CA-OLSR), i.e., so that it uses content names as routing labels. Then, we have integrated CA-OLSR with the popularity-based caching strategy, which caches only the most popular content (MPC). On the other hand, we have considered two similar architectures for conducting performance comparative studies. The first is pure Fog-based CDN implemented by the original OLSR (IP-based routing) protocol along with the default caching strategy. The second is a classical cloud-based CDN implemented by the original OLSR. Through extensive simulation experiments, we have shown that our Fog-based CDN architecture outperforms the other compared architectures. CA-OLSR achieves the highest packet delivery ratio (PDR) and the lowest delay for all simulated numbers of connected users. Furthermore, the MPC caching strategy shows higher cache hit rates with fewer numbers of caching operations compared to the existing default caching strategy, which caches all the pass-by content.
Highlights
Content retrieval has become the primary usage of the Internet
Content Delivery/Distribution Networks (CDNs) have become the main part of Internet architecture, since they help improve the quality of Internet services (QoS) as well as the quality of users’ experience (QoE) [2]
To evaluate the caching strategy of Fog CDN approaches, we have studied the impact of popularity threshold and Fog node cache size on caching performance in terms of the following measures: (i) Local cache hit rate (LCHR): the ratio of requests that are satisfied by the local caches of attached Fog nodes (HL) versus the total number of requests (R)
Summary
Content retrieval has become the primary usage of the Internet. To solve content availability and download time issues, Content Delivery/Distribution Networks (CDNs) [1, 2] have evolved as virtual overlay networks built on top of existing network infrastructures. Real-time and latencysensitive applications, like video streaming, are delivered out of place, and the user experience is affected To overcome this issue, we have proposed [5] a Fog-based CDN architecture, in which Fog nodes are introduced at the edges of CDN servers without disrupting the conventional CDN infrastructure. The performance of the proposed model is evaluated using a network simulator tool and is compared with two similar architectures The first is another Fog-based CDN model, in which Fog nodes are introduced as native cache resources, while the request routing is performed by the original OLSR (IP-based routing).
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