As a result of the unprecedented demand, news websites took a number of steps to enhance their ability to handle the traffic. Since the Internet technologies group at CNN was represented at the committee, CNN’s experience, in particular, and the strategies it employed are documented in the report. On September 11, CNN’s overall demand surged greatly, with page views increasing on September 11 to 132 million-nearly 10 times the more typical load of 14 million on September 10. The number of page hits (pages or images requested) doubled every 7 minutes, resulting in an order of magnitude increase in less than 30 minutes. The demand for news continued to increase following the attack, reaching 304 million page views on September 12-more than twice that measured on September 11 CNN responded with a combination of several techniques to deal with the load: Reduced web page complexity: CNN had a strategy in place for dealing with high-demand periods that called for reducing web page complexity. Accordingly, on 9/11, the CNN.com main web page was significantly reduced in size by eliminating elements such as headline pictures and graphical menu bars. In fact, the main page was stripped down to the bare bones –even further than the usual minimum –to increase its ability to serve pages. At its minimum complexity, the CNN.com home page could fit into a single IP packet. Adding more servers: CNN’s other servers normally used for other CNN and Turner Broadcasting content were experiencing significantly reduced volume that day. A number of them were reconfigured and added to the CNN.com server pool. Interestingly, CNN did retain server capacity for the Cartoon Network, which saw an increase in volume –likely reflecting parents’ desire to provide children with an alternative to the disturbing news. Temporarily employing a third-party content-distribution network. CNN increased its use of the Akamai content-delivery network to reduce the load on the CNN servers themselves.
5 CASE QUESTIONS 1.Describe some of the damage caused to communications networks due to Hurricane Katrina. (5) 2.Describe some of the damage caused to communications networks on 9/11. (10) 3.Why is text messaging and VoIP more reliable than circuit-switched voice networks? (10) 4.What are content delivery networks? How does content caching differ from content delivery network? How are the content delivery networks useful during disasters? (10) 5.What were some changes in Internet traffic patterns on 9/11? (5) 6.Why is it useful to reduce the size of a web page so it fits into one IP packet? (5) 7.What is a possible extreme disaster that is likely to strike your city? Create a disaster recovery plan for communication that will allow you to maintain communication with the two most important people in your life in case this disaster strikes your town. (5)