Interception caching is still somewhat controversial. Even though it sounds like a great idea initially, you should carefully consider the following issues before deploying it on your network.
If for some reason, one of your users encounters a problem with interception caching, he or she is going to have a difficult time getting around the cache. Possible problems include stale pages, servers that are incompatible with your cache (but work without it), and IP-based access controls. The only way to get around an interception cache is to configure a different proxy cache manually. Then the TCP packets are not sent to port 80 and thus are not diverted to the cache. Most likely, the user is not savvy enough to configure a proxy manually, let alone realize what the problem is. And even if he does know what to do, he most likely does not have access to another proxy on the Internet.
In my role as a Squid developer, I’ve received a number of email messages asking for help bypassing ISP settings. The following message is real; only the names have been changed to protect the guilty:
Duane, I am Zach Ariah, a subscriber of XXX Internet - an ISP who has recently installed... Squid/1.NOVM.21. All of my HTTP requests are now being forced through the proxy(proxy-03-real.xxxxx.net). I really don't like this, and am wondering if there is anyway around this. Can I do some hack on my client machine, or put something special into the browser, which will make ...