Article Review 1: DARPA

Summary

The paper discusses in detail how the DARPA internet protocols used today were developed.

The fundamental goal of the DARPA Internet Program was to develop a technique for utilizing the currently existing networks of the Department of Defense. This fundamental goal can be described in detail by seven second-level goals, which identifies in order of importance the desirable features of an effective interconnection. The most important goal in the list states that internet communication must continue despite of loss of networks or gateways. To achieve this goal, the fate-sharing approach, wherein it is acceptable to lose the state information of an entity being transmitted over the network if the entity itself is also lost, was chosen over replication. Another goal is that the internet should be able to support a variety of services. As a result, the TCP and IP protocols -- which were originally just 1 protocol, were created as two separate layers. A third goal was to incorporate and utilize a wide variety of network technologies – including military and commercial facilities. The basic assumption in achieving this flexibility is to have a datagram or packet of reasonable size with acceptable delivery.

The top 3 goals of survivability, supporting a variety of types of service, and accommodating a variety of networks, had the most effect in the existing architecture of the internet today. The other remaining goals were not met as effectively. The challenge today is to design networks using the existing internet protocols that would best fit the desired performance levels and type of service required. The author suggests exploring alternative building blocks from the datagram, and one he specified is called “flow”. The gateways will monitor the flow state to remember the nature of the flows that are passing through them. Then endpoints will enforce what type of service will be associated with the flow by sending messages. The DARPA Internet Program is currently conducting explorations of alternative building blocks .

Background

What is DARPA?

The Defense Advanced Research Projects Agency (DARPA) is an agency of the United States Department of Defense responsible for the development of new technology for use by the military. DARPA has been responsible for funding the development of many technologies which have had a major impact on the world, including computer networking, as well as NLS, which was both the first hypertext system, and an important precursor to the contemporary ubiquitous graphical user interface.

DARPA is independent from other more conventional military R&D and reports directly to senior Department of Defense management. DARPA has around 240 personnel (about 140 technical) directly managing a $3.2 billion budget. These figures are "on average" since DARPA focuses on short-term (two to four-year) projects run by small, purpose-built teams.

http://en.wikipedia.org/wiki/Defense_Advanced_Research_Projects_Agency

Critique

I honestly found the beginning of this paper boring. It was a struggle just getting past the first page. Surprisingly enough the material becomes a more interesting read when the goals were being discussed and the pros and cons for choosing one method over another were being explained. Overall, the DARPA internet project is a good example that not all project goals can be achieved (whether this is planned failure or a sad reality, is subject to argument). And many times, certain aspects have to be sacrificed in order to make way for more important objectives.

As a last note, I found it really funny on how the author subtly injected humor by saying that he does not have an idea on how to guide the procurement person (at DARPA?) who did not make sure that the performance specifications were in the procurement documents, but let slide limitations that would limit the performance goals.

Main Reference:

Design philosophy of the DARPA internet protocols

by David C. Clark