Above is a cybernetic model of TCP/IP protocol in the context of sending or receiving a 50 KB photo. The TCP/IP protocol functions as a comparator - a component of a closed-loop system that compares information coming from a sensor to the system goal. In the case of TCP/IP, the protocol checks if a data transmission (divided into packets) is complete and assembled in the right order; anything less than completion and the protocol can request for parts of that data to be transmitted again.
This exercise seeks to determine the what of my thesis, the content; it does not necessarily refer to the overall topic, but the actual category and detail of content so as to define the why, how, who for, who by, where, and when. This exercise is not a linear process where defining what first is necessary, rather to grasp exactly what is being studied, however granular.
On pursuing a thesis about the environmental effects of cloud-based computing, I need to better understand what I am measuring as well as the infrastructure (so I can determine where and when is the best point for intervention). The what in my case is data - little bits of 0’s and 1’s that live on your hard drive, and are subsequently stored and transmitted by remote server(s). The more data, the more energy consumed by the server.
Data is measured in bits and bytes (8-bits); you’ve most likely seen the data on your computer in megabytes (MB) or gigabytes (GB). When you send any type of data over the Internet such as an email, photo, or gchat message, your data is divided up into packets. On average, the size of these packets are 576 bytes or 4,608 bits, and consist of a header and trailer, with the data in between. You may or may not know that your computer has an IP (Internet Protocol) address - a unique numerical identifier for every device on a network. Even websites have IP addresses. The header of each data packet would contain information on the origin or sending IP address, destination or receiving IP address, and total size of the packet. The trailer of each data packet would contain information on how many packets there are and in what order to reassemble them back into the original data.
If I were to send a friend a 50 KB photo, the photo would be broken up into approximately 87 IPv4 (Internet Protocol version 4) data packets and then sent out across the Internet. The TCP/IP protocol checks if any packets are missing, request packets from the sending computer, and notify the sender that the transmission is complete. This operation of error checking is called cyclic redundancy checking and used by networked devices when sending and receiving transmissions.
Direct transmission of data, which can be ineffiecient and take time (think of a landline phone call), is an obsolete method of transmission for the Internet. However, due to the non-linear nature of the IP protocol, a Google search request for example is not handled by one server, but by several, to give faster, more relevant results. There is acutally a carbon footprint estimated by Google for the average search request: about 0.2 grams of CO2. Along with the power a laptop consumes, Mike Berners-Lee estimates a Google search creates 0.7 grams of CO2. Multiply that by the 200 to 500 million search requests per day, and Google searching actually accounts for 1.3 million tons of CO2 emissions per year.
References:
Berners-Lee, Mike. How Bad Are Bananas? The Carbon Footprint of Everything. Vancouver: Greystone, 2011.
“Bit” definition, Wikipedia, accessed December 18, 2011. link
Ethan Zuckerman and Andrew McLaughlin, “Introduction to Internet Architecture and Institutions,” August, 2003, accessed December 18, 2011. link
Greg Ferro, “Average IP Packet Size,” Ethereal Mind, March 18, 2010, accessed December 18, 2011. link
Hugh Dubberly and Paul Pangaro, “Introduction to Cybernetics and the Design of Systems,” January 2010.
“Network packet” definition, Wikipedia, accessed December 18, 2011. link
Swanson, Joe. Interview by author. Written notes. Cambridge, MA., November 20, 2011.
Urs Hölzle, “Powering a Google Search,” Google Blog, January 1, 2009, accessed December 3, 2011. link
