Implementing ISA Server Caching

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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 users point of view, caching
  improves Internet access performance
• From the network administrators point of view,
  caching provides the added benefit of reducing
  the use of network bandwidth

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Basics of Web ProxyCaching
Web server
http//vnexpress.net
ISA SERVER
http//vnexpress.net
http//vnexpress.net
Cache
http//vnexpress.net
http//vnexpress.net
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Benefit of Web Caching

• Improved performanceBecause 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 usageBecause 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

http//vnexpress.net
http//vnexpress.net
ISA SERVER
Cache
http//vnexpress.net
http//vnexpress.net
YES
Check the requested content
NO
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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
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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
• Improve Internet access performance and decrease
  the use of bandwidth to the Internet!!

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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
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ISA 2006s 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 RAM
• Not use the same drive on which the operating
  system and/or ISA firewall application are
  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 Rules
If 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 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

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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?
http//vnexpress.net http//dantri.com.vn http//t
intuconline.net http//tuoitre.com.vn
ISA
cache
http//tintuconline.net http//tuoitre.com.vn
Head Office
http//vnexpress.net http//dantri.com.vn
ISA
ISA
Branch Office
cache
cache
Branch 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
Check requested content
NO
YES
Check requested content
NO
Send the request to upstream server
ISA
cache
YES
Return requested content
ISA
cache
Head Office
Send request
Branch Office