Easy Way to Remember Osi Layers Silver
Today I'm talking a little bit about the OSI model. What is the OSI model you ask?? OSI stands for => "Open Systems Interconnection" and it is used to describe the 7 layers that computer systems use to communicate over a network. It was the first standard model for network communications, adopted by all major computer and telecommunication companies in the early 1980s.
Todays internet is not based on OSI but based on a simpler TCP/IP model. However the OSI 7 layer model is still widely used. OSI was introduced in 1983 by representatives of major computer and telecom companies and was adopted by ISO as an international standard in 1984.
I've had trouble remembering the structure off the bat so, here is a phrase that I've found helps others , and now myself, to remembering all 7 layers.
"All People Seem To Need Data Processing"
OSI Network Model
7.Application
6.Presentation
5.Session
4.Transport
3.Network
2.Data Link
1.Physical
Layer 7 – Application Layer
The Application is the end of the line so to speak! It provides the interface for the user. A few examples of application layer protocols are the Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), Post Office Protocol (POP), Simple Mail Transfer Protocol (SMTP), and Domain Name System (DNS).
Layer 6 – Presentation Layer
Presentation layer prepares the data for the application layer. Defines how 2 devices should encode, encrypt, and compress data so it is correctly received on the other end.
Layer 5 – Session Layer
Session layer creates the communication channels, called sessions, between devices. It is responsible for opening a channel and keeping it open while the data is being transferred and closing the session when the communication ends. Session layer can also set checkpoints during a data transfer – if the session is interrupted, devices can resume data transfer from the last checkpoint.
Layer 4 – Transport Layer
Transport layer takes data transferred in the session layer and breaks it into "segments" on the transmitting end. It is responsible for reassembling the segments on the receiving end, turning back into data that can be used by the session layer. The transport layer carries out flow control, sending data at a rate that matches the connection speed of the receiving device, and error control, checking if data was received incorrectly and if not, requesting it again.
Layer 3 – Network Layer
Network layer has 2 functions. 1 is breaking up segments into network packets, and reassembling the packets on the receiving end. The 2nd is routing packets by discovering the best path across a physical network. The network layer uses network addresses (typically Internet Protocol addresses) to route packets to a destination node.
Layer 2 – Data Link Layer
Data Link Layer establishes and terminates a connection between two physically-connected nodes on a network. It breaks up packets into frames and sends them from source to destination. This layer is composed of two parts—Logical Link Control (LLC), which identifies network protocols, performs error checking and synchronizes frames, and Media Access Control (MAC) which uses MAC addresses to connect devices and define permissions to transmit and receive data.
Layer 1 – Physical Layer
The physical layer is responsible for physical cable or wireless connection between network nodes. It defines the connector, the electrical cable or wireless technology connecting the devices, and is responsible for transmission of raw data, which is simply a series of0s and 1s, while taking care of bit rate control.
There you have it, just a little bit on the OSI model to get you started. There's so much to learn and if you want to learn networks this is just the beginning! It's helped me and others remember. Just doing my part to spread the word. Thanks for reading up! Keep on coming back!
Much love and aloha
Source: https://rileyrudd.com/2022/03/04/easy-to-remember-osi-model/
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