Transparently Guaranteeing Fault Tolerance, Geographic Affinity, and Load Balanced Mirror Sites

Brian Wingenroth, Web Development Specialist, Johns Hopkins University Press, Baltimore, Maryland, US. Email: brian@muse.jhu.edu

Thomas Maszczenski, Unix Systems Administrator, Johns Hopkins University Press, Baltimore, Maryland, US. Email: thom@muse.jhu.edu

Keywords

DNS Failover, Closest Copy, Geolocation, Geo-location, Mirroring, Replicated Web Sites, Web Mirror

Abstract

In theory, content providers use mirror sites to enhance the reliability, efficiency and flexibility of their web sites. However simply setting up a mirror site guarantees none of these benefits. Each mirror site is configured with a different Internet Protocol (IP) address and possibly a different domain name. The only way one can access the mirror is by knowing its IP address a priori. Various solutions to this problem have been proposed, yet each has unique flaws. This paper presents another solution, that utilises communication between mirror sites to enable transparent failover in the event of a single site failure, transparent redirection of a user to the closest copy of the web site, and the incorporation of load balancing to distribute requests so that a single site is not disproportionately overburdened. We propose a solution that demands nothing of the end user and very little from the content provider. Our software solution can be implemented at any web site, realising the potential benefits of a mirror site.