Designing an Internet

Why the Internet was designed to be the way it is, and how it could be different, now and in the future.

How do you design an internet? The architecture of the current Internet is the product of basic design decisions made early in its history. What would an internet look like if it were designed, today, from the ground up? In this book, MIT computer scientist David Clark explains how the Internet is actually put together, what requirements it was designed to meet, and why different design decisions would create different internets. He does not take today's Internet as a given but tries to learn from it, and from alternative proposals for what an internet might be, in order to draw some general conclusions about network architecture.

Clark discusses the history of the Internet, and how a range of potentially conflicting requirements--including longevity, security, availability, economic viability, management, and meeting the needs of society--shaped its character. He addresses both the technical aspects of the Internet and its broader social and economic contexts. He describes basic design approaches and explains, in terms accessible to nonspecialists, how networks are designed to carry out their functions. (An appendix offers a more technical discussion of network functions for readers who want the details.) He considers a range of alternative proposals for how to design an internet, examines in detail the key requirements a successful design must meet, and then imagines how to design a future internet from scratch. It's not that we should expect anyone to do this; but, perhaps, by conceiving a better future, we can push toward it.

為什麼互聯網被設計成現在這樣的形式，以及它在現在和未來可能會有什麼不同。

你如何設計一個互聯網？現有互聯網的架構是在早期做出的基本設計決策的結果。如果從頭開始設計，現代的互聯網會是什麼樣子？在這本書中，麻省理工學院的計算機科學家大衛·克拉克解釋了互聯網的實際組成方式，它被設計來滿足什麼要求，以及為什麼不同的設計決策會創造出不同的互聯網。他不僅僅接受現有的互聯網，還試圖從中學習，並從其他對互聯網可能性的提議中獲取一些關於網絡架構的一般結論。

克拉克討論了互聯網的歷史，以及一系列潛在衝突的要求，包括持久性、安全性、可用性、經濟可行性、管理和滿足社會需求，如何塑造了它的特性。他既討論了互聯網的技術方面，也討論了其更廣泛的社會和經濟背景。他描述了基本的設計方法，並以非專業人士可以理解的方式解釋了網絡如何設計來執行其功能。（附錄提供了更多技術討論，供希望了解細節的讀者參考。）他考慮了一系列關於如何設計互聯網的替代提議，詳細檢視了成功設計必須滿足的關鍵要求，然後想像如何從頭開始設計未來的互聯網。我們不應該期望有人真的這樣做，但或許通過構想一個更好的未來，我們可以朝著它前進。

David D. Clark is a Senior Research Scientist at the MIT Computer Science and Artificial Intelligence Lab and a leader in the design of the Internet since the 1970s.

David D. Clark是麻省理工學院計算機科學與人工智慧實驗室的高級研究科學家，自1970年代以來一直在互聯網設計領域中擔任領導者。