Literature Reviews

"The Design Philosophy of the DARPA Internet Protocols" By David D Clark.

This paper was about the design decisions when the internet was first being established and how those decisions have affected the internet that is currently used today. These decisions were based upon the following assumptions. The first is that there would be other types of networks to connect to. This first assumption lead to the decision to use packet switching since that methodology was already being used in the networks that were being used at that time. The other main assumption that was stated was that “networks would be interconnected by a layer of Internet packet switches, which were called gateways.” These assumptions lead to the basic structure of the Internet: “a packet switched communication facility in which a number of distinguishable networks are connected together using packet communications processors called gateways which implement a store and forward packet forwarding algorithm.” Once the basic structure was determined, the developers of the Internet created a list of seven secondary goals and based upon the requirements of that time, the put the list together in order of importance. The first three goals have been fully implemented, while the last four goals have been partially completed. The first goal is that the internet will function properly regardless of a loss of networks or gateways; this meant that if two computers were communicating over the network, and one of the routers that it was going to fails, that the computers can still continue to communicate without having to reestablish a connection. The second and third goals are related to one of the original assumptions in that it must be able to handle multiple types of communication services and networks. These goals are related to the requirements of the networks or services in the speed, latency and reliability that is needed for the various services. This goal led to the development of Transmission Control Protocol (TCP) and Internet Protocol (IP). TCP provides a reliable sequence stream of data, while IP was the building block that networks and services can be built upon to create their more complex requirements. The last four goals deal with the distributed management of resources, the architecture being cost effective, host attachment must be done with a low level of effort, and that the architecture must be accountable.

"Rethinking the design of the Internet: The end to end arguments vs. the brave new world" By David D. Clark and Marjory S. Blumenthal.

This paper discusses some of the arguments that are related to the end to end argument. The end to end argument is that the end points of a line of communication should handle the functionality of the communication. An example for an argument against staying with a strict end-to-end Internet is by applying a mail filtering system on the email server which could filter out spam mail. This violates the end to end principal since the function of removing the spam is now at the server, before it gets to the end user. Although some see this functionality as not breaking the end to end argument, since the function is just applied at the entity directly before it arrives at the end user, it still not a true end to end system in which one end user sends an email message to another end user, since the message has to be filtered in some way at a point between the users. One disadvantage of moving away from the end to end system is that the protocols that are currently being used and implemented in the Internet would either become more complex then they currently are, or the protocols would have to be removed and completely new protocols would have to be established. However, in making the current protocols more complex or by creating newer (and more then likely complex) protocols, some of the original designs and goals of the Internet would led to a demise of the current properties and functionality of the Internet.

"Scriptroute: A Public Internet Measurement Facility" By Neil Spring, David Wetherall and Tom Anderson

This paper describes in detail Scriptroute, which is "a system that allows ordinary Internet users to conduct network measurements from remote vantage points" (Scriptroute). There are three main goals that the developers of Scriptroute took into consideration when designing and implementing their system. They are to be provided by the community, to be of broad use and to be of lasting value. They were able to make the system be available to all Internet users by having the only validation of their IP address. Additionally, they designed their system with many possible measurement tools that would be of use for research, along with allowing additional flexibility for new tools to be added. The authors of this paper also went to into much detail about the various ways in which they set restriction access and resource consumption to protect the Scriptroute servers. Some of these restrictions is that the Scriptroute server limits the measurement access that a script can use. These limits include, but are not limited to, the duration, processor time and number of concurrent measurements. Also, the developers of Scriptroute added that Scriptroute servers cannot create denial-of-service attacks. They did this by logging the client activity in order for the measurement traffic to be traced to its origin and by limiting the measurement traffic to a low, background level. With these limitations Scriptroute is able to fulfill the main three goals of the project.

"End-to-End Internet Packet Dynamics" By Very Paxson

This paper discusses the dynamics of packet transmission from one end point in the Internet to another end point. Prior to the completion of the paper, there had been two experiments that had been conducted, which led to the conclusions stated in the paper. The two experiments were conducted one year apart, so that there could be analysis done on what changed in the course of that year. They first discussed the various unusual behaviors that were detected in the experiments. Some of these behaviors was out-of-order delivery (in spite of the fact that Internet routers are indeed based on the FIFO concept), packet replication, and packet corruption. Then the authors discussed a couple of different approaches to determine the bottleneck bandwidth between two end points. The bottleneck bandwidth can be defined as the point in which the speed of the message passing is at its slowest in the course of the path from the end points. The two methods of determining the bottleneck bandwidth are "packet pair" and "packet bunch modes." There was also a discussion on the effectiveness of "packet pair" when the algorithms for the "packet bunch modes" was applied, and how they then received similar results. Additionally, packet loss was analyzed between the two different experiments which led to conclusions about loss rates, loss bursts (when more then one loss occurred in a consecutive order), and the efficiency of the TCP retransmissions. Finally, packet delay was discussed in regards to timing compression, queue time scales, and the available bandwidth.

"The Timed Asynchronous Distributed System Model" By Flaviu Cristian and Christof Fetzer

This paper discusses the timed asynchronous distributed system model, which makes five major assumptions. These assumptions are that all servers are timed, interprocess failures are due to a message that is dropped or that is late, a process itself can only crash or have a performance failure, processes have access to a hardware clock (which is within a degree of certainty synchronous with real time), and the last assumption is that there is no bound for the communication frequency or process failure in a given system. The remainder of the paper discussed the various assumptions in detail and the extensions that could be implemented as a result of the timed asynchronous distributed system model. Two of the extensions are to provide stable network storage and to have network progress assumptions in which a process has a set amount of time to get to a certain point in its tasks.