Label Servers

Because proxy servers must deal with the entire data stream, they must be scaled to handle all of the data. Label servers only deal with the actual data being filtered - usually the URL and a bit of additional information from the HTTP request headers. This allows them to concentrate solely on filtering, offering much higher performance. In lab tests I've seen an improvement of 200 times (from 25 requests per second to 5000 requests per second) on identical hardware using identical filtering software and identical lists.

Label servers must be used in conjunction with some other software, as they don't offer a complete solution by themselves. This can either be proxy software, client software, or software embedded into a routing or switching device.

For example, Internet Explorer includes a PICS client which can be used with label servers. Unfortunately, there are no large-scale implementations of compatible label servers, so the capability is seldom, if ever, used.

There is at least one commercial implementation of a label server which can communicate with the freely available Squid proxy server. There are not yet any announced label server products that work with routers or switches.