Implementing ISA Server Caching

Basics of Web Proxy Caching Definition: A Web cache sits between one or more Web servers (also known as origin servers) and a client or many clients, and watches requests come by, saving copies of the responses for itself. Then, if there is another request for the same URL, it can use the response that it has, instead of asking the origin server for it again

Basics of Web Proxy Caching ISA Server supports caching as a way to improve the speed of retrieving information from the Internet. From the internal user’s point of view, caching improves Internet access performance From the network administrator’s point of view, caching provides the added benefit of reducing the use of network bandwidth

Basics of Web Proxy Caching Web server http://vnexpress.net http://vnexpress.net ISA SERVER http://vnexpress.net Cache http://vnexpress.net http://vnexpress.net

Benefit of Web Caching Improved performance:Because the request is satisfied from the client instead of the origin server, it takes less time for the client to get the object Reduced bandwidth usage:Because each object is only gotten once from the server, it reduces the amount of bandwith used by a client

Web Caching Types Forward caching: accelerates the response to outbound requests when users on the internal network request a Web object from a server on the Internet Reverse caching: accelerates the response when a user on the Internet makes a request for Web content that is located on a Web server on the internal network

Check the requested content How Web Caching Works Forward caching http://vnexpress.net http://vnexpress.net ISA SERVER Cache http://vnexpress.net http://vnexpress.net YES Check the requested content NO

Check the requested content How Web Caching Works Reverse caching http://vnexpress.net http://vnexpress.net ISA SERVER Cache http://vnexpress.net http://vnexpress.net YES Check the requested content NO

Content Download Jobs By monitoring and analyzing Internet access, can determine which Web content is most likely to be requested by internal clients. Content download jobs allow to schedule content for download at a specific time or at recurring times Improve Internet access performance and decrease the use of bandwidth to the Internet!!

How Content Download Job Works Web server http://vnexpress.net http://vnexpress.net ISA SERVER http://vnexpress.net Cache http://vnexpress.net http://vnexpress.net

ISA 2006’s Web Caching Enabling and Configuring Caching Understanding Cache Rules Understanding the Content Download Feature

Enabling and Configuring Caching The cache drive must be a local drive The cache drive must be on an NTFS partition When caching an object, ISA Server first places an object into the RAM cache and then writes objects to disk. By default, ISA Server uses 10 percent of the RAM Not use the same drive on which the operating system and/or ISA firewall application are installed!

Enabling and Configuring Caching

Understanding Cache Rules Cache rules allow customize what types of content will be stored in the cache and exactly how that content will be handled when a request is made for objects stored in cache. Content Types can be cached: Dynamic content Content for offline browsing Content requiring user authentication for retrieval

Understanding Cache Rules

Understanding Cache Rules If use Forward Caching

Understanding Cache Rules Using Cache Rules to Specify How Objects are Retrieved and Served from Cache

Understanding the Content Download Configuring Content Downloads: Ensure a content download job can run Create and configure a scheduled content download job Make changes to an existing content download job Disable or delete a content download job Export or import content download job configurations Run a content download job immediately

Understanding the Content Download Ensure a Content Download Job Can Run Enabling Web Proxy Clients

Understanding the Content Download Create and Configure Scheduled Content Download Jobs

Web Chaining and Caching Some organizations include multiple locations with computers running ISA Server deployed in each location. Combine caching with Web proxy chaining to optimize caching performance All Internet requests are routed through one location at the head office

Why use caching for web chaining? http://vnexpress.net http://dantri.com.vn http://tintuconline.net http://tuoitre.com.vn ISA cache Head Office http://tintuconline.net http://tuoitre.com.vn http://vnexpress.net http://dantri.com.vn ISA ISA Branch Office cache cache Branch Office

Implement Web Chaining and Caching Install ISA Server in each office Configure ISA Server at the branch offices to route all Internet requests to the ISA Server computer at the head office The head-office ISA Server will develop a large cache that contains many requested items.

Web Chaining and Caching Check requested content NO YES Check requested content NO ISA Send the request to upstream server cache YES Return requested content ISA cache Head Office Send request Branch Office