Page requests are first passed to a front-end layer of Squid caching servers. Requests that cannot be served from the Squid cache are sent to load-balancing servers running the Perlbal software, which in turn pass the request to one of the Apache web servers for page-rendering from the database. The web servers deliver pages as requested, performing page rendering for all the language editions of Wikipedia. To increase speed further, rendered pages for anonymous users are cached in a filesystem until invalidated, allowing page rendering to be skipped entirely for most common page accesses. To further accelerate response times, Wikimedia is building a global network of caching servers, beginning with three caching servers in France. Two larger clusters in the Netherlands and Korea now handle much of Wikipedia's traffic load.