Transcript Implementing ISA Server Caching

Implementing ISA Server
Caching
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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
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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
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Basics of Web Proxy
Caching
Web server
http://vnexpress.net
http://vnexpress.net
ISA SERVER
http://vnexpress.net
http://vnexpress.net
Cache
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
http://vnexpress.net
http://vnexpress.net
ISA SERVER
Cache
http://vnexpress.net
http://vnexpress.net
YES
NO
Check the
requested
content
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How Web Caching Works
• Reverse caching
http://vnexpress.net
http://vnexpress.net
http://vnexpress.net
ISA SERVER
Cache
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
ISA SERVER
http://vnexpress.net
http://vnexpress.net
Cache
http://vnexpress.net
http://vnexpress.net
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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 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?
Branch Office
http://vnexpress.net
http://dantri.com.vn
http://tintuconline.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
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
NO
YES
ISA
NO
cache
Check
requested
content
YES
ISA
Head Office
cache
Send
request
Branch Office
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