Turning on web caching for HTTP and HTTPS traffic

Web caching can be applied to any HTTP or HTTPS traffic by enabling web caching in a security policy that accepts the traffic. This includes IPv4, IPv6, WAN optimization and explicit web proxy traffic. Web caching caches all HTTP traffic accepted by a policy on TCP port 80.

You can add web caching to a policy to:

• Cache Internet HTTP traffic for users on an internal network to reduce Internet bandwidth use. Do this by selecting the web cache option for security policies that allow users on the internal network to browse web sites on the Internet.
• Reduce the load on a public facing web server by caching objects on the FortiGate unit. This is a reverse proxy with web caching configuration. Do this by selecting the web cache option for a security policy that allows users on the Internet to connect to the web server.
• Cache outgoing explicit web proxy traffic when the explicit proxy is used to proxy users in an internal network who are connecting to the web servers on the Internet. Do this by selecting the web cache option for explicit web proxy security policies that allow users on the internal network to browse web sites on the Internet.
• Combine web caching with WAN optimization. You can enable web caching in any WAN optimization security policy. This includes manual, active, and passive WAN optimization policies and WAN optimization tunnel policies. You can enable web caching on both the client-side and the server-side FortiGate units or on just one or the other.

For optimum performance you can enable web caching on both the client-side and server-side FortiGate units. In this way only uncached content is transmitted through the WAN optimization tunnel. All cached content is access locally by clients from the client side FortiGate unit.

One important use for web caching is to cache software updates (for example, Win- dows Updates or iOS updates. When updates occur a large number of users may all be trying to download these updates at the same time. Caching these updates will be a major performance improvement and also have a potentially large impact on redu- cing Internet bandwidth use. You may want to adjust the maximum cache object size to make sure these updates are cached. See Max cache object size on page 2891.