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Networking - For The Cloud

Some important Networking concepts that are essential for design and implementation of cloud based projects.

Networking ..? What is it ? Computer networking is simply the process of connecting computers (or any other “computing” device) so that they can communicate - share information, resources etc. We have one computer, we have another computer…. Lets connect them so they can talk to each other….. You just made a network….. I play on my computer, you play on your computer…. Lets connect our computers so we can play together…… you now benefit from computer networking. This gets you started but eventually you want to connect mode devices, you want better performance, you want to connect with computers in different parts of the world and you want to keep dreaming bigger. Therefore computer networking and the devices, protocols, standards etc required to support your demands need to grow too. All of this put together is “Networking”.

The most essentials parts of a network include – 1.The host/Node/End user device – This is the device that needs to communicate. This will connect to the network and communicate with other devices/ hosts/ nodes etc. This is usually the user’s device – your computer, phone, server etc. 2.Networking hardware/device – These are the building blocks of the network. They facilitate communication between user devices (hosts, nodes, servers etc.). These are not the devices that “need” to communicate but the devices that help devices that “need” to communicate. Basically, these devices build the network so your devices can benefit from it. 3.Media – Cables, radio waves, Wi-fi etc. Stuff that carries your data between devices and from one point to another. 4.Protocols, Standards etc. – All games have rules. These are rules (and regulations) that participating devices must play by so every device in the network knows how to speak to and understand others. This is your rules book every device on the network must know and follow.

Reference models – for your reference only A reference model simply outlines the steps that must be followed (and their sequence) so that devices know what they have to do in order to begin, accept or participate in communication. DO NOT think of these as laws. These are more like suggestions or recommendations. Lets say you want to learn to drive, There are certain things you need to learn in order to drive a car. You need to know how to operate a car, how to control a car in motion and the laws you must follow while you are on the road. If you don’t even know how to operate a car, there is no benefit to knowing traffic rules because you will never actually be able to get your car on the road. Many rules remain the same but some vary with the type of vehicle, type of road, the specific rules in your country and maybe even weather conditions. You should know the general rules of driving but how to implement or follow them vary on many factors. Similarly any device that wants to communicate on a network should keep in mind the “layers” of the reference model and the rules to be followed one ach layer but how these “layers” are implemented may vary on different networks. All of this just to say, Reference models are for reference only. In the end, you do you.

Think of two people trying to communicate verbally.

  • They may speak different languages.

  • They may speak the same language but with different dialects.

  • They may speck the same language with different accents or pronunciations.

  • They may have different vocabulary ranges etc.

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All of these and more may make communication difficult. The more these things are in common between the speakers, the smoother the communication.

The reference model helps your communicating devices speak the same language and ensure they share and understand all the nuances of their “shared language”.

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Two reference models –

The OSI Model – Open Systems Interconnection.

7 layers. Mostly theoretical. Very limited practical usage.

 

When a device wants to communicate on the network, lets say you are using a web browser on your laptop and you open youtube.com, your device now needs to connect to youtube.com and establish a connection. Then information starts flowing between your laptop and the Youtube server (and all the networking devices and media in between).

 

How should the browser on your laptop begin the connection ? How does data leave your laptop and flow through the networking devices and media and how is it processed by the Youtube server ?

 

    7.  Application Layer – This is where your browser is. This is the layer at which users interact with the host devices.  

    6.  Presentation Layer – This is about formatting data, making sure its usable and encryption.

    5.  Session Layer – Maintains connections at the port level and controls sessions – communication channel open and available- between two            devices.   

    4.  Transport Layer – Ensures end to end communication for applications. This layer controls speed, segments data and may provide error                 recovery and flow control.

    3.   Network Layer – responsible for moving data between networks. This is where IP addresses become relevant. Manages your devices                       logical identity on the network and connects it to other networks – including far away networks.  Manages data in form on packets.

    2.   Data Link Layer – Manages data transfer between nodes – host to host, host to networking device etc. Manages data in form of frames.                 This is where the physical address of your device (or network card) becomes relevant and facilitates connection.

    1.    Physical layer – This is the layer where the media – cables, fiber optic, wi-fi etc operate.  Core functions is transmission of raw data                         signals over the “wires”, manage synchronization etc.

 

TCP/IP - 4 layers only. Actual model the internet operates on. More practical than the OSI model.

Functions that are performed by multiple layers in the OSI model are combined into one in the TCP/IP model.

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  1.  Application Layer – Where the user interacts with the applications running on the device. Session maintenance, data                                             formatting etc are also performed here. Protocols like HTTPS , DHCP etc.

  2.  Transport Layer – Supports end to end communication support for the applications. Ports are associated with different                                       applications and help move data between them. Protocols : TCP, UDP etc.

  3.  Internet Layer – This is where the logical addressing happens. Responsible for moving data between networks through                                   optimal routes. IP works here.

  4.  Network Layer – Responsible for transmitting data over the media- cabels, wi-fi etc. MAC addresses are relevant here.                                     Data moves between hops or nodes (not between networks). Ethernet, Wi-fi etc function here.

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