Globally Distributed Content Delivery

Presenter: Baoning Wu03/25/2003

Motivation

• Flash crowd problem• Overload can crash web sites and

cause high response time

• Akamai’s system

Akamai’s network infrastructure

• Allocate more servers to sites experiencing high load and serve all clients from nearby servers.

• The system directs client requests to the nearest available server likely to have the requested content.

How to find servers?

• Dynamic DNS system

Criteria for name servers to resolve IP address

• Service requested• Server health• Server load• Network condition• Client location• Content requested

DNS resolution

• A7.g.akamai.net

• Root name server ->• .net name server ->• .akamai.net name server(top

level)->• .g.akamai.net name server(low

level)

Network services

• Static content– Use cache, apply lifetime

• Dynamic content– Assemble dynamic content on edge

server

• Streaming media– Windows Media, Real, Apple’s

QuickTime

Challenges

• Scalability– Must scale to many distributed

servers

• Reliability– Both hardware and software

• Software deployment– Deploy new network software in

stages

Challenges (continue)

• Content visibility and control– Cache consistency– Lifetime control– Authentication and authorization– Integrity control– Visibility into access patterns– billing

•Questions?