The Design Philosophy of the DARPA Internet Protocols

This paper written by David D. Clark discusses the internet and its protocols, reflecting on it's design goals and evaluating the success and implementation of each goal. It first gives a brief history of the DARPA network and lists the goals in which the developers had in mind when designing it.

"The fundamental goal for the internet architecture was to develop an effective technique for multipexed utilization of existing interconnected networks. " Writes Clark. This meant combining all the preexisting commonly used networks (including the ARPA packet radio network, ARPANET etc) together so they can communicate and share information. And the technique selected for that was packet switching. Along with the fundamental goal, there are also second level goals, including fault tolerant, multiple types of services etc. The paper goes on to discuss in detail the second level goals, and how the implementation came to be why each implementation was decided.

The paper was definitely a good read. David Clark was the chief protocol architect in the development of the internet, so he obviously knew what he was talking about. He used explained each goal and the reasonings behind it, giving us a good picture of what was going on in his mind during that time.

The internet is something we take for granted everyday, and it's almost becoming something we can't live without. Looking back at the design goals, the fundamental goal of interconnecting a wide range of networks is probably what gave the internet its popularity today. Being able to connect to people from all over the world through these different sets of mediums is why the internet is so attractive, and is the definition of the internet itself. And the benefits of fault tolerant allows us a pretty reliable network to use.

We can see the tradeoff between the flexibility of the internet along with the performance. It was interesting reading Clark describing how the internet architect is actually something that can't really be described, because it encapsulates such a wide range of services, so it can only be defined by the end point services themselves. And the performance (latency) of the internet also cannot fully be comprehended because the design goal is to support any network of any latency. But because of that, we are seeing the internet being used in ways no one would have ever imagined when the internet was designed. Because of the flexibility in services, today the internet is even moving onto the mobile platforms and revolutionizing out experience with interacting with the network.

However, with the internet technology continues to evolve, it will be interesting to see the backwards compatibility continue to play in its effect. How much longer will apps or developers continue to support slow networks like 56k modem etc, given the fact that the design goals of the internet was to incorporate all the different networks into one giant network.