1. Implementing ISA Server Caching

2. 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

3. 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

4. Basics of Web Proxy Caching
Web server
ISA SERVER
Cache

5. 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

6. 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

7. Check the requested content
How Web Caching Works
Forward caching
ISA SERVER
Cache
YES
Check the requested content NO

8. Check the requested content
How Web Caching Works
Reverse caching
ISA SERVER
Cache
YES
Check the requested content NO

9. 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!!

10. How Content Download Job Works
Web server
ISA SERVER
Cache

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

12. 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!

13. Enabling and Configuring Caching

14. 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

15. Understanding Cache Rules

16. Understanding Cache Rules
If use Forward Caching

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

18. 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

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

20. Understanding the Content Download
Create and Configure Scheduled Content Download Jobs

21. 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

22. Why use caching for web chaining?
ISA
cache
Head Office
ISA
ISA
Branch Office
cache
cache
Branch Office

23. 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.

24. 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