Cloud Definable Networking: Caching

Nowadays, caching technology is no longer a new technology to reduce the response time to the user’s request through various ways, such as proxy caching [32] and transparent proxy caching [2]. Through Web caching, the network traffic is minimized when the user is surfing the Internet, while the access speed is also extensively raised [5]. As the core of Content Distribution Network (CDN) is to increase the access speed of the Internet, caching technology is one of the most important technology for CDN, and the Web cache server is the core of caching system and CDN [28].

Cache server can be a common server installing with the caching software or a special equipment including the software and hardware system. In brief, cache server plays the role of filtration and agency between the original server and users.

It can filter the users redundant request to save the bandwidth of backbone network and increase the response speed. In addition, it can get the information for users from the original server as an agency. As shown in Fig. 4.1, it illustrates the position and function of the cache server. If the requested content is reserved in the cache server, it will response to the user’s request directly. Otherwise, the cache server will send the request to the original server on behalf of the user and then copy and retransmit the response to the user.

Web caching reserves the frequently accessed content in the cache server at the edge of network and provides the users with these contents rapidly. Thus, it could release the burden of the original server and the redundant flow of backbone network, while the response time is shortened.