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diff --git a/content/en/docs/Concepts/what.md b/content/en/docs/Concepts/what.md index 54a0ca8..b0c6196 100644 --- a/content/en/docs/Concepts/what.md +++ b/content/en/docs/Concepts/what.md @@ -1,75 +1,13 @@ --- -title: "What is a recursive network?" +title: "Recursive networks" author: "Dimitri Staessens" -date: 2019-07-06 -weight: 1 +date: 2020-01-11 +weight: 2 description: > - Introduction to recursive networks. + The recursive network paradigm --- -# The current networking paradigm -{{<figure width="40%" src="/docs/concepts/aschenbrenner.png">}} - -Every computer science class that deals with networks explains the -[7-layer OSI model](https://www.bmc.com/blogs/osi-model-7-layers/). -Open Systems Interconnect (OSI) defines 7 layers, each providing an -abstraction for a certain *function* that a network application may -need. - -From top to bottom, the layers provide (roughly) the following -functions: - -The __application layer__ implements the details of the application -protocol (such as HTTP), which specifies the operations and data that -the application understands (requesting a web page). - -The __presentation layer__ provides independence of data representation, -and may also perform encryption. - -The __session layer__ sets up and manages sessions (think of a session -as a conversation or dialogue) between the applications. - -The __transport layer__ handles individual chunks of data (think of them -as words in the conversation), and can ensure that there is end-to-end -reliability (no words or phrases get lost). - -The __network layer__ forwards the packets across the network, it -provides such things as addressing and congestion control. - -The __datalink layer__ encodes data into bits and moves them between -hosts. It handles errors in the physical layer. It has two sub-layers: -Media access control layer (MAC), which says when hosts can transmit -on the medium, and logical link control (LLC) that deals with error -handling and control of transmission rates. - -Finally, the __physical layer__ is responsible for translating the -bits into a signal (e.g. laser pulses in a fibre) that is carried -between endpoints. - -This functional layering provides a logical order for the steps that -data passes through between applications. Indeed, every existing -(packet) network goes through these steps in roughly this order -(however, some may be skipped). There can be some small variations on -where the functions are implemented. For instance, TCP does congestion -control, but is a Layer 4 protocol. - -However, when looking at current networking solutions, things are not -as simple as these 7 layers seem to indicate. Just consider this -realistic scenario for a software developer working remotely. Usually -it goes something like this: You connect to the company __Virtual -Private Network__ (VPN), setup an SSH __tunnel__ over the development -server to your virtual machine and then SSH into that virtual machine. - -The use of VPNs and various tunneling technologies draw a picture -where the __functions__ of Layers 2, 3, and 4, and often layers 5 and -6 (encryption) are __repeated__ a number of times in the actual -functional path that data follows through the network stack. - -Enter __*recursive networks*__. - -# The recursive network paradigm - The functional repetition in the network stack is discussed in detail in the book __*"Patterns in Network Architecture: A Return to Fundamentals"*__. From the observations in the book, a new architecture |