1 Implementing ISA Server Caching. 2 Basics of Web Proxy Caching Definition: A Web cache sits...

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Implementing ISA ServerCaching

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Basics of Web ProxyCaching

• 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

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Basics of Web ProxyCaching

• 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

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Basics of Web ProxyCaching

CacheCache

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Web serverWeb server

http://vnexpress.nethttp://vnexpress.net

http://vnexpress.nethttp://vnexpress.net

http://vnexpress.net

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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

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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

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How Web Caching Works

• Forward caching

CacheCache

http://vnexpress.net

Check the requested content

Check the requested content

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http://vnexpress.net

YESYES

NONO

http://vnexpress.net

http://vnexpress.net

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How Web Caching Works

• Reverse caching

CacheCache

http://vnexpress.net

Check the requested content

Check the requested content

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http://vnexpress.net

YESYES

NONO

http://vnexpress.net

http://vnexpress.net

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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

IImprove Internet access mprove Internet access performance and decrease the use of bandwidth decrease the use of bandwidth to the Internet!!

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How Content Download Job Works

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Web serverWeb server

http://vnexpress.nethttp://vnexpress.net

http://vnexpress.net

http://vnexpress.net

http://vnexpress.net

CacheCache

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ISA 2006’s Web Caching

• Enabling and Configuring Caching• Understanding Cache Rules• Understanding the Content Download Feature

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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 RAMNot use the same drive on which the operating Not use the same drive on which the operating

system and/or ISA firewall application are system and/or ISA firewall application are installed!installed!

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Enabling and Configuring Caching

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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

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Understanding Cache Rules

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Understanding Cache RulesIf use Forward CachingIf use Forward Caching

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Understanding Cache Rules

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

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Understanding the Content Download

• Configuring Content Downloads:Ensure a content download job can runCreate and configure a scheduled content

download jobMake changes to an existing content download

jobDisable or delete a content download jobExport or import content download job

configurationsRun a content download job immediately

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Understanding the Content Download

• Ensure a Content Download Job Can Run

• Enabling Web Proxy Clients

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Understanding the Content Download

• Create and Configure Scheduled Content Download Jobs

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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

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Why use caching for web chaining?

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cachecachecachecache

cachecache

http://vnexpress.nethttp://dantri.com.vn

http://tintuconline.nethttp://tuoitre.com.vn

http://vnexpress.nethttp://dantri.com.vn

http://tintuconline.nethttp://tuoitre.com.vn

http://vnexpress.nethttp://dantri.com.vnhttp://vnexpress.nethttp://dantri.com.vn

http://tintuconline.nethttp://tuoitre.com.vn

http://tintuconline.nethttp://tuoitre.com.vn

Branch OfficeBranch OfficeBranch OfficeBranch Office

Head OfficeHead Office

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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.

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Web Chaining and Caching

Branch OfficeBranch Office

Head OfficeHead OfficeSend request

Send the request to

upstream server

Return requested

contentcachecache

cachecache

Check requested

content

Check requested

content

NONO

YESYES

Check requested

content

Check requested

contentNONO

YESYES

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