Akamai Content Delivery Network

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Akamai Content Delivery Network

• Slides from Bruce Maggs

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HTML Title Page for www.xyz.comwith Embedded
Objects

• lthtmlgt
• ltheadgt
• lttitlegtWelcome to xyz.com!lt/titlegt
• lt/headgt
• ltbodygt
• ltimg src
• ltimg src
• lth1gtWelcome to our Web site!lt/h1gt
• lta hrefpage2.htmlgtClick here to enterlt/agt
• lt/bodygt
• lt/htmlgt

http//www.xyz.com/logos/logo.gifgt
http//www.xyz.com/jpgs/navbar1.jpggt
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Downloading www.xyz.com - before Akamai
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WWW.XYZ.COM

• Browser obtains IP addresses for hostnames listed
  in URLs of objects embedded on page

• User enters www.xyz.com

• Browser requests IP address for www.xyz.com

• Browser requests embedded objects

• DNS returns IP address

• Browser requests HTML

• Content providers web server returns embedded
  objects

• Content providers web server returns HTML

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DNS Resolution
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Problems with the Centralized Approach

• Slow
• content must traverse multiple backbones and long
  distances
• Unreliable
• delivery may be prevented by congestion or
  backbone peering problems
• Not scalable
• usage limited by bandwidth available at master
  site
• Inferior streaming quality
• packet loss, congestion, and narrow pipes degrade
  stream quality

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The Akamai Solution

• Monitors the Internet and routes around trouble
  spots
• Distributes all forms of content and supports
  applications
• Provides feedback on hit counts to content
  providers

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Downloading www.xyz.com - The Akamai way

• Content providers web server returns page with
  Akamaized URLs

• User enters www.xyz.com

• Browser obtains IP address of optimal Akamai
  server for embedded objects

• Browser requests IP address for www.xyz.com

• DNS returns IP address

• Browser obtains objects from optimal Akamai server

• Browser requests HTML

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Content Delivery Using Akamai

• lthtmlgt
• ltheadgt
• lttitlegtWelcome to xyz.com!lt/titlegt
• lt/headgt
• ltbodygt
• ltimg src
• ltimg src
  
• lth1gtWelcome to our Web site!lt/h1gt
• lta hrefpage2.htmlgtClick here to enterlt/agt
• lt/bodygt
• lt/htmlgt

http//www.xyz.com/logos/logo.gifgt
http//www.xyz.com/jpgs/navbar1.jpggt
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Typical Page Content
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Akamai DNS Resolution
End User
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Advantages of the Akamai Solution

• Fast
• Content is served from locations near to end
  users
• Reliable
• No single point of failure
• Automatic fail-over
• Scalable
• Master site no longer requires massive available
  bandwidth

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Network Deployment
10000Servers
500Networks
55Countries
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Results
Web Site Performance Typical Improvement with
Akamai
Noon May 15
Noon May 16
Noon May 17
Noon May 18
Noon May 19
Noon May 20
Noon May 21
Noon May 22
Noon May 23
Noon May 24
Noon May 25
Noon May 26
Noon May 27
Web object delivered by Akamai
Web object delivered without Akamai
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Over 1300 Web Sites are Now Akamaized
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Hashing
E.g., h(x) (((a x b) mod P) mod B) ,
where P is prime, P gt U a,b chosen uniformly
at random from ZP x is a serial number
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Difficulty changing number of buckets
4 3 2 1 0
bucket
5 7 10 11 27 29 36 38 40 43
object
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Consistent Hashing
Idea Map both objects and buckets to unit
circle.