Content Delivery Networks

1. Content Delivery Networks

3. History • Early 1990s sees 100% growth in internet traffic per year • 1994 • Netscape forms and releases their first browser • Yahoo created • W3C founded • 1995 - 1996, internet traffic grows by 1000% per year • 1995  • Java released • Internet Explorer released • 1996 • Google created at Stanford • WebTV Introduced • 1998 - Akamai forms • 1999 - Akamai signs a deal with Apple to deliver QuickTime content

4. Problems • Files keep getting larger • Internet Usage keeps increasing • Flash crowds/Slashdot effect • The distance between end points causes added latency

5. Solutions • Caching • Keep things in memory • Dynamic content is reused with TTL rather than regenerated • Caching proxy servers • Server Clusters • Load balancer routes to servers in a cluster, usually based on load • Edge Nodes • Requests are routed to edge nodes based on location

6. Request Routing • Layer 4 Load Balancer • Does not look at request content • Often knows the status of the servers it routes to • Layer 4-7/Web/Application Switch • Inspects request content • Can do some processing, such as SSL • Can be cookie aware • DNS Based Routing • Resolves a domain name to different IP addresses • Link Load Balancing • Often there is more than one route to a host, always make sure to select the best one

7. Clients Replicated Edge Servers Origin Server

8. Akamai • Over 61,000 servers in over 70 countries • Commodity hardware with distributed software • http://www.akamai.com/ • Data Visualization • Tour Akamai's NOC

9. P2P CDN • Pros • Efficient use of bandwidth • Lower Cost • Cons • No QoS • Requires cooperation from clients • Not good for unpopular things

10. P2PTV

11. BitTorrent