Web caching and SSL offloading

FortiGate web caching is a form of object caching that accelerates web applications and web servers by reducing bandwidth usage, server load, and perceived latency. Web caching supports caching of HTTP 1.0 and HTTP 1.1 web sites. See RFC 2616 for information about web caching for HTTP 1.1.

Web caching supports caching of Flash content over HTTP but does not cache audio and video streams including Flash videos and streaming content that use native streaming protocols such as RTMP.

The first time a file is received by web caching it is cached in the format it is received in, whether it be compressed or uncompressed. When the same file is requested by a client but in a different compression format, the cached file is converted to the new compressed format before being sent to the client.

There are three significant advantages to using web caching to improve HTTP and WAN performance:

• reduced bandwidth consumption because fewer requests and responses go over the WAN or Internet.
• reduced web server load because there are fewer requests for web servers to handle.
• reduced latency because responses for cached requests are available from a local FortiGate unit instead of from across the WAN or Internet.

You can use web caching to cache any web traffic that passes through the FortiGate unit, including web pages from web servers on a LAN, WAN or on the Internet. You apply web caching by enabling the web caching option in any security policy. When enabled in a security policy, web caching is applied to all HTTP sessions accepted by the security policy. If the security policy is an explicit web proxy security policy, the FortiGate unit caches explicit web proxy sessions.