704 IEEE COMMUNICATIONS LETTERS, VOL. 22, NO. 4, APRIL 2018
SCDN: A Novel Software-Driven CDN for Better Content Pricing and Caching
Jie Duan, Yuan Xing , Ruilin Tian, Guofeng Zhao, Shuai Zeng, Yuanni Liu, and Chuan Xu
Abstract—In conventional content delivery networks (CDNs),
where the content providers (CPs) are lack of the topology
information, it is difficult for them to determine the content
caching and pricing scheme. Furthermore, the small CPs cannot
maintain their own cache servers as it is costly. To solve these
problems, we propose a novel CDN architecture named software-
driven CDN (SCDN) by leveraging the benefit provided by
the software defined networks. In SCDN, the infrastructure
provider (IP) hosts the cache servers at the back of the digital
subscriber line access multiplexer, and it takes over the tasks to
determine the content pricing and caching. By adopting a suitable
revenue sharing scheme, SCDN achieves a win-win situation
between IP and CPs. Simulation results show that with SCDN,
the CPs can get about 25% more revenue than they can get in
conventional CDNs.
Index Terms— SCDN, content pricing, caching, revenue.
I. INTRODUCTION
N
OWADAYS, more and more people get information from
the Internet, entertain themselves with the online video
and audio streaming. All of these result in the exponential
growth of content-based services and applications. It is esti-
mated that the video traffic will be 82 percent of all consumer
Internet traffic by 2021 [1]. Accordingly, it is important for
content providers (CPs) to offer good content delivery services.
To this end, some researchers proposed a framework
named Content Delivery Networks (CDNs) [2]. In CDNs,
the CPs host many cache servers, whenever a customer
requests some content, the corresponding CP let the most
suitable cache server (usually the closest one) to respond
to the request. This is a way to enhance the Quality of
Services (QoS) of the customers, however, it is not the best
solution as it has following drawbacks: 1) CPs do not have the
topology information, which is hosted by the Infrastructure
Provider (IP), and hence it is difficult for the CPs to derive
the best decision on which contents to be cached; 2) it is
difficult to estimate which cache server is the best one that
should respond to the customer’s request, since the closest
one is not always the quickest one that responds to the
request, as the content should be delivered cross the Internet;
3) for small CPs, it is expensive for them to operate their
own cache servers, which limits the application of CDNs.
There are some existing works that are focusing on how
to optimize the content caching and delivery in the CDNs.
Manuscript received January 6, 2018; accepted February 4, 2018. Date
of publication February 8, 2018; date of current version April 7, 2018.
This work was supported by the National Natural Science Foundation of
China under Grant Nos. 61701058, 61501075, 61671130 and 61671124; the
Foundation for Sci & Tech Research Project of Chongqing under Grant
No. cstc2016jcyjA0560. The associate editor coordinating the review of this
letter and approving it for publication was G. Zheng. (Corresponding author:
Guofeng Zhao.)
The authors are with the School of Communication and Informa-
tion Engineering, Chongqing University of Posts and Telecommunications,
Chongqing 400065, China (e-mail: duanjie@cqupt.edu.cn; xingystudy@
foxmail.com; trlwork@foxmail.com; zhaogf@cqupt.edu.cn; zengshuai@
cqupt.edu.cn; liuyn@cqupt.edu.cn; xuchuan@cqupt.edu.cn).
Digital Object Identifier 10.1109/LCOMM.2018.2803808
As one of the representative works, the authors in [3] assume
the CPs host cache servers at the access network in order
to shorten the latency that customers experience and mitigate
the workload in the backbone networks. However, hosting
cache server by each CP is very costly for the small CPs.
Furthermore, they did not consider how to price the content
so as to maximize the revenue. Reference [4] also discusses
how to cache and deliver content based on the cache server
location and routing policy. This work assumes the network
topology is known to the CPs, however, this is not the case
in most of the networks. Cloud-Oriented Content Delivery
Network (CCDN) [5] improves the conventional CDNs by
introducing the Cloud concept. It treats the CDN as multiple
cloud and leverages the technologies in cloud computing
to optimize the content delivery. Similar to other related
works, CCDN does not consider the pricing scheme to opti-
mize the revenue. The CDN-as-a-Virtual-Network-Function
approach [6] is proposed by using the distributed network
functions virtualization platform at the edge of ISP’s network
to solve the ISP-CDN collaboration revenue problem. How-
ever, only the pricing part is considered.
Recently, Software Defined Networks (SDN) [7] is proposed
to enhance the functionality of network plane. Based on the
most famous SDN protocol, OpenFlow, the IP can record
the content request information on the network switches.
In addition, it has the entire network topology information.
Motivated by this fact, we propose a novel CDN architecture
named Software-driven CDN (SCDN). In SCDN, the IP hosts
all the cache servers behind the Digital Subscriber Line
Access Multiplexer (DSLAM) [8], which are used to cache
the contents for the customers in the same area.
In SCDN, we suggest the IP taking over the permission
of pricing and making the cache decision. In this way, not
only the customers can experience a better QoS, but also
the IP can better optimize the pricing and caching schemes.
By leveraging a suitable revenue sharing scheme, both the IP
and CPs can get more revenue with SCDN than that they are
in the conventional CDNs. Even if the CPs would not like
to release the permission of pricing and caching decision to
the IP, they can rent the cache capacity from the IP and offer
a better QoS to the customers and earn more revenue.
The remaining part of this letter is organized as follows.
We introduce the SCDN and discuss how to make the con-
tent pricing and caching decisions in SCDN in Section II,
followed by extensive performance evaluations in Section III.
In Section IV, we conclude this letter.
II. A
RCHITECTURE AND ANALYSIS
To clarify presentation, we first introduce the SCDN archi-
tecture detailedly in Section II-A. Based on the SCDN,
in Section II-B, we theoretically analyze how the IP caches the
content and set the price of the content requested by customers.
Then, we present a way for the IP to share the revenue in
Section II-C. At last, in Section II-D, we discuss the case that
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