D.D. Clark published this paper in 1988 almost fifteen years after the first TCP/IP proposal which was developed by DARPA. It is interesting to understand why certain directions were taken by the original designers and what was the evolutionary road internet took during those fifteen years.
The DARPA internet project was launched in order to effectively interconnect two distinct networks being ARPANET and ARPA packet radio network and this effective connection was the fundamental goal of the project. Being able to effectively connect networks can be seen as a genetic mutation in the networks evolutionary pattern which enabled much more scalable and complex networks to be built compared to networks which are designed and upgraded uniformly!
Two of the original approaches of the internet, being datagram and packet switching , were already existing in the networks under investigation and were the default candidates. Furthermore they had shown by that time (and continued to show in the future) to be valid choices compared to their competitors such as virtual networks paradigm.
The author also lists secondary and lower tier goals across his paper. Since these networks were being originally designed for military applications, reliability and robustness to failures was put at the top of the secondary list while the accountability was put at the end of secondary list. Noting that this paper was written in 1988, the author claims that if internet was being designed for a commercial application these two choices would needed to be swapped! I find this point of view interesting since it suggest that in 1988 the importance of reliability was not as evident in commercial applications. Today's commercial applications count on the reliabilty of the internet and an unreliable internet can have a destructive effect on many commercial applications today. I would assume if Clark had written this paper in 2009 he would have only ranked accountability higher and keep the reliability at the top two in the secondary list.
It is also notable the couple of places that Clark implicitly points to the usage of end-to-end argument as described by the first paper we have read. One being the "fate-sharing" story in which by keeping the state information at the end-entities rather than network and the other one being the separation of services from the datagram facility (TCP and IP layers).
I would also like to point out that throughout this paper it does not look like scalability is considered to be an important issue. This is likely due to the year this paper was published and might suggest that the number of networks was still not too big. For example the suggestion at the end of the paper about the "soft state" does not consider the possible scalability problems due to such structure.
I would very much like this paper to be kept in the syllabus since it makes students think about the evolutionary path of internet and helps them obtain a more fundamental understanding of it.
The DARPA internet project was launched in order to effectively interconnect two distinct networks being ARPANET and ARPA packet radio network and this effective connection was the fundamental goal of the project. Being able to effectively connect networks can be seen as a genetic mutation in the networks evolutionary pattern which enabled much more scalable and complex networks to be built compared to networks which are designed and upgraded uniformly!
Two of the original approaches of the internet, being datagram and packet switching , were already existing in the networks under investigation and were the default candidates. Furthermore they had shown by that time (and continued to show in the future) to be valid choices compared to their competitors such as virtual networks paradigm.
The author also lists secondary and lower tier goals across his paper. Since these networks were being originally designed for military applications, reliability and robustness to failures was put at the top of the secondary list while the accountability was put at the end of secondary list. Noting that this paper was written in 1988, the author claims that if internet was being designed for a commercial application these two choices would needed to be swapped! I find this point of view interesting since it suggest that in 1988 the importance of reliability was not as evident in commercial applications. Today's commercial applications count on the reliabilty of the internet and an unreliable internet can have a destructive effect on many commercial applications today. I would assume if Clark had written this paper in 2009 he would have only ranked accountability higher and keep the reliability at the top two in the secondary list.
It is also notable the couple of places that Clark implicitly points to the usage of end-to-end argument as described by the first paper we have read. One being the "fate-sharing" story in which by keeping the state information at the end-entities rather than network and the other one being the separation of services from the datagram facility (TCP and IP layers).
I would also like to point out that throughout this paper it does not look like scalability is considered to be an important issue. This is likely due to the year this paper was published and might suggest that the number of networks was still not too big. For example the suggestion at the end of the paper about the "soft state" does not consider the possible scalability problems due to such structure.
I would very much like this paper to be kept in the syllabus since it makes students think about the evolutionary path of internet and helps them obtain a more fundamental understanding of it.
:-(
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