Ming-Chen Zhao, Paarijaat Aditya, Yin LinAndreas Haeberlen, Peter Druschel, Bruce Maggs, and William Wishon

A First Look at a Hybrid Content Delivery System

Powering a Better Internet © 2011 Akamai

Akamai Network Deployment

160000+Servers

1000+Networks

79+Countries

2500+POPs

Powering a Better Internet © 2011 Akamai

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

Powering a Better Internet © 2011 Akamai

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

Powering a Better Internet © 2011 Akamai

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

Powering a Better Internet © 2011 Akamai

Growth in Number of Installations

Full product roll-out expected summer 2011.

Powering a Better Internet © 2011 Akamai

Architecture

• BitTorrent-like protocol with control nodes serving as “trackers” and assigning peers

• CDN acts as a backstop

Akamai Control Nodes Akamai Edge Servers

Peers

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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

Powering a Better Internet © 2011 Akamai

Statistics from December 2010 Logs

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Locations of Clients per EdgeScape

Granularity of predictions varies by continent.

Powering a Better Internet © 2011 Akamai

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.

Powering a Better Internet © 2011 Akamai

Ongoing Work

• Designing mechanisms to protect the logging system against attacks

• (Successfully attacked it ourselves.)