9.5. An Overview of Existing Platforms
We have considered a large number of proxy cooperation models. Not all of them have been widely deployed. This section describes platforms for cooperative caching that are deployed on the Internet at the time of this writing.
9.5.1. Cache Hierarchies
Many geographical regions have built extensive caching hierarchies. They were initially constructed around the broadcast queries cooperation model and the ICP protocol that implements them. They have since evolved to include a mix of broadcast queries, cache digests, and URL namespace partitioning (which is equivalent to URL hashing where the hash function is defined manually in the configuration files of individual proxies). Together, cache hierarchies comprise ...