Intel 1520 User Manual

Intel NetStructure Cache Appliance Administrator’s Guide

The Intel NetStructure Cache Appliance is a high-performance caching proxy 
server. It is designed to efficiently handle multiple client connections 
simultaneously and supports HTTP, FTP, NNTP, ICP, and WCCP 2.0 protocols. 

The idea behind Web caching is to store copies of frequently accessed documents 
close to users and serve this information to them on demand. Users get their 
information faster, and Internet bandwidth is freed up for other tasks. 

Users direct their requests to Web servers all over the Internet. For a caching 
server to serve these requests, it must act as a Web proxy server. A Web proxy 
server fields user requests to arbitrary Web servers and either serves the requests, 
or forwards them on to the origin server (the Web server that contains the original 
copy of the requested information). 

The proxy supports both transparent proxy caching, where the user’s client 
software is unaware that it is communicating with a proxy, and explicit proxy 
caching, where client software (typically a browser) must be expressly pointed at 
the proxy. Transparent proxy caching is discussed in more detail on page 120.

A day in the life of a cache request

Here is an overview of the steps that take place as the appliance acts as a proxy 
cache and serves a user request.

The appliance receives a user request for a document, image, news article, or 
other Web object.

With the object address in hand, the appliance looks up the requested object in its 
object database (cache).

If the object is in the cache, the appliance checks to see if the object is fresh 
enough to serve. (See Ensuring cached object freshness‚ on page 115 for details.) 
If the object is fresh, the appliance serves it to the user as a cache hit (Figure 1). 

request

a cache hit

returned document

client