Global Mirror for APS Research Journals (January 24, 2000)

We use the Digital Island [1] system for direct internet connectivity to many countries outside the United States. Our testing indicates it provides more consistent round-the-clock responsiveness than traditional internet service providers. We generally send all outgoing traffic to one of the listed countries over the Digital Island network; to get traffic flowing over this network in both directions, please use our mirror server at: http://mirror.publish.aps.org/ [2]

As of January 24, 2000 the covered countries are:

Australia, Brazil, Canada, China, France, Germany, Hong Kong, Ireland, Israel, Italy, Japan, Mexico, the Netherlands, Russia, Singapore, South Africa, South Korea, Spain, Sweden, Switzerland, Taiwan, the UK

Explanation

Since early 1997 the APS has been investigating reports of problems with international internet connectivity to the web sites supporting our research journals, for both the online journals and editorial and author support services. The fact that there were at least some problems was clear, although quantitative measurement and tracking of the sources proved more difficult. Many of the problems could be traced to congested inter-network bottlenecks such as the US Metropolitan Area Exchanges (MAE-East and West), others were clearly related to oversubscribed data links crossing the Atlantic and Pacific. Some of these problems were alleviated by improvements in international connectivity particularly among research and scientific networks. An upgraded link between the Japanese SInet and the US considerably improved the situation for researchers in Japan, and similar dramatic improvements were seen for various European countries as they were added to the Ten-34 network, which had high-capacity under-utilized links to the US.

In spite of these improvements, it seemed worthwhile for the APS to investigate possible active steps that could be taken to improve the international accessibility of our journal web sites. Many users suggested overseas mirrors, and in fact the APS headquarters web site (http://www.aps.org/ [3]) has had a mirror arrangement with the European Physical Society for some time (see http://epswww.epfl.ch/aps/ [4]). This particular arrangement did not prove suitable for extension to the research journals material of primary interest, however, and in particular was not capable of handling the many interactive functions (author submissions and inquiries for example) that are handled at the research journals web site. And just serving one geographical location is really not enough - probably a dozen locations would be more suitable, but then the cost for a dozen hundred-gigabyte storage systems and appropriate server machines becomes prohibitive (at least for the next few years), and there will likely be significant maintenance charges for most such arrangements.

Instead, in collaboration with Stanford University's HighWire Press [5], we began an investigation of buying dedicated "pipes" to our international users through the Digital Island [1] service. In brief, Digital Island is a commercial company that purchases connectivity to local internet providers in a variety of countries around the world (see table above) and then provides one-hop connections between those countries and a server located in a Digital Island data center or two-hop connections to an existing server elsewhere. Highwire has now been using the Digital Island service for over a year. We conducted some more extensive tests on our end and were not completely satisfied with some of the performance - nevertheless the improvement for some countries was significant, and from July 1998 we have a one-year contract, during which we will continue monitoring the performance levels.

In the current implementation the "mirror" and regular server machines are one and the same, the only difference being the network connectivity. The one exception is the online journals for which the regular server is AIP's OJPS site, and for which the "mirror" server works as a proxy. These details are likely to change in future as we try to improve the speed and reliability of the systems. The actual implementation of the networking is asymmetrical - all outgoing data from "publish.aps.org" and "mirror.publish.aps.org" flows over either the Digital Island link or our regular US internet link (currently UUNet), depending on the IP address of the destination. All incoming data to "publish.aps.org" comes through the UUnet link however, and all incoming data to "mirror.publish.aps.org" comes through the Digital Island network. These details may also change.

The "mirror" also provides us back-up internet connectivity in case our primary network links fail, as happened this past July when a fiber cable was cut near Philadelphia. It does not yet provide back-up in case of disaster at the publication office, but we are working towards a more redundant and reliable system in future. At the least it provides an alternate link that improves the connectivity and stability of the APS research journals web site. Feedback is more than welcome - please send any problems or other comments to help@aps.org [6].