A First Look at a Hybrid Content Delivery System
Ming-Chen Zhao, Paarijaat Aditya, Yin Lin
Andreas Haeberlen, Peter Druschel, Bruce Maggs, and William Wishon
Akamai Network Deployment
85800+ 1795+ 1000+ 79+
POPs Networks Countries
Servers
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Akamai Peak Instant and Daily Statistics
• Bit rate (01/09/11): 4.8 Tbps
• Request rate (02/21/11): 16.7 million hits/sec
• Bytes delivered (12/27/10): 42.3 Pbytes
• HTTP requests received (02/21/11): 961.5 billion
• Unique client IPs (02/16/11): 471.5 million
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Download Manager Product/Service
• Hybrid between a fixed-infrastructure CDN
and a pure peer-to-peer delivery system
• Based on technology developed by
Red Swoosh (acquired by Akamai in 2007)
• Goal is to deliver large files at lower cost
• In beta operation today
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NetSession Interface
• client-side software
• runs as a service on Windows or MacOS
• provides an API to installation software or
browser
• stays connected to an Akamai Control Node
• each installation is supposed to have a
unique GUID
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Growth in Number of Installations
Full product roll-out expected summer 2011.
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Architecture
Peers
Akamai Control Nodes
Akamai Edge Servers
• BitTorrent-like protocol with control nodes
serving as “trackers” and assigning peers
• CDN acts as a backstop
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Logging
• Content providers want all downloads to be
logged
• Peers must report P2P downloads to control
nodes as they occur
• Akamai Edge Servers also log downloads from
peers
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Statistics from December 2010 Logs
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Locations of Clients per EdgeScape
Granularity of predictions varies by continent.
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December Client Logins
What happened December 8?
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IP Addresses per GUID in December
Category 3 (flagged) look like multiple
installations with the same GUID.
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Clients Leave P2P Setting Unchanged
Content provider decides on initial setting.
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File Size Distribution
For customers other than J and F, median file
size was 872MB.
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P2P Efficiency for Largest Enabled Customers
Matches or exceeds earlier predictions.
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Efficiency versus Number of Peers
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Success Rates, All Downloads
Over 86% success rate in December 2010.
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Terminations and Failures Occur Early
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Performance
Majority P2P downloads average several Mbps.
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Content Popularity
Typical?
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NetSession Versions Observed in Field
NetSession should excel at downloading itself.
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Ongoing Work
• Designing mechanisms to protect the logging
system against attacks
• (Successfully attacked it ourselves.)
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© 2011 Akamai