in order to accomodate content caching as you've described you need, for an enterprise class environment, you'll want to check out the Cisco CSS line of content switches.
a quick view of the CSS abilities for content caching includes:
(taken from cco documentation)
* examining network traffic for web content requests
* bypassing the cache automatically for non-cachable content
* distributing content requests to maximize cache hits
* bypassing the cache or redistributing requests among the remaining cache services if a cache service fails
* proxy caching capabilities.
among other capabilities, this device would allow you to create a 'farm' of web servers where your content can be housed utilizing faster response times and high availability.
please see the following link for more info on the CSS and its abilities:
(there are other 'model' versions of the CSS than the one linked here)
http://www.cisco.com/en/US/products/hw/contnetw/ps792/products_data_sheet0900aecd800f851e.html
