Paper review: <The Design Philosophy of The DARPA Internet Protocols>

Reviewer: <Gang Li>

1. This paper tries to capture some of the early reasoning which shaped the Internet protocols.
2. Although there have been papers and specifications that describe how the Internet protocol suite, TCP/IP, works, it is sometimes difficult to deduce from these why the protocol is as it is.
   
   The main contribution of this paper is that the author catalogs one view of the original objectives of the Internet architure, and discusses the relation between these goals and the important features of the protocols, hence gives us a clear view of the reasons that coined the Internet protocols.
3. The author divides the goals to several levels to illustrate.
   
   First, the fundamental goal for the DARPA Internet Architecture was to develop an effective technique for multiplexed utilization of existing interconnected networks. Using practical analysis, the author convinces us that the fundamental structure of the Internet should be: a packet switched communications facility in which a number of distinguishable networks are connected together using packet communicaitons processors called gateways which implement a store and forward packet forwarding algorithm.
   
   Second, the second level goals summarizes a more detailed set of goals which were established for the Internet architecture. Furthermore these goals are in order of importance. For example, since this network was designed to operate in a military context, which implied the possibility of a hostile environment, survivability was put as a first goal, and accountability as a last goal. But an architecture primarily for commercial deployment would clearly place these goals at the opposite end of the list.
   
   The most important goal on the previous list is that the Internet should continue to supply communications service, even though networks and gateways are failing. In particular, this goal was interpreted to mean that if two entities are communicating over the Internet, and some failure causes the Internet to be temporarily disrupted and reconfigured to reconstitute the service, then the entities communicating should be able to continue without having to reestablish or reset the high level state of their conversation. Which means at the service interface of the transport layer, this architecture provides no facility to communicate to the client of the transport service that the synchronization between the sender and the receiver may have been lost. Naturally we arrive at "fate-sharing", taking the information and gather it at the endpoint of the net, at the entity which is utilizing the service of the network, which is exactly chosen by this architecture.

4. The structure of the Internet was deeply afftected by military methodology.

5. I give 3(modest contribution) stars to this paper. It tells us the strcuture of the Internet by illustration, which is convincing. My reservation is that this is a review paper, hence don't have much meaningful research significance per se.
   
   This paper is quite convincing, since the author illustrates by giving real examples and concerns.