An OpenFlow based Optimal Selection Mechanism for Multiple Web Servers.

Web based Internet services normally will be constructed with multiple redundant servers considering fault tolerance, load balancing and traffic distribution. As an easy and popular way Domain Name System (DNS) based round robin technology has been well used. An end client will receive multiple IP address for a web server from DNS based domain name resolution and normally the first one will be used for the access. However, the first IP address will not necessarily be the locationally nearer one or the one with lower workload. As a result, neither the service provider can provide efficient Internet service nor the end client can use the Internet service comfortably. In this paper, we propose an OpenFlow based optimal selection mechanism for multiple web servers with collaboration of DNS based domain name resolution in prior to accessing the web servers. In the proposed mechanism, the OpenFlow technology has been used for latency probing to each web server using the IP addressed received from the DNS response. A prototype system based on the proposed mechanism has been implemented in a local network environment and the functionalities have been evaluated. According to the results, we confirmed that the one with lower latency among the multiple web servers can be successfully selected for the end client and the sessions from the others can be reset with low overhead.