What is Layer in networking?

Question

I mean what does mean layer Is this a sotware or physically device in networking?

Answer 1

When working with computers, every task has to be broken down into little steps. (Kind of like a teenage - You can't just say "Clean your room", you have to say "Make the bed", hang up the clean clothes", "Put the dirty ones in the basket", etc.).

With networking you can just say "Send this information for Computer A to Computer B". You have to detail each step. Those steps are referred to as "layers".

The standard model, defined by a computer advisory group called OSI, has seven layers
1: application
2: presentation
3: session
4: transport
5: network
6: data link
7: physical

(Should you ever want to memorize the list, think: All People Seem To Need Data Processing)

There is an agreement on what goes into each layer and what comes out of each layer, but it is up to the individual program or device to decide what happends within each layer. Meaning, when you get down to the physical layer, you have information all packed and ready to go. It is reaching you in an agreed upon format. You have to get it to the other computer in an agreed upon format. But HOW you get it there will be different if you are going over a cable as opposed to going wireless. One uses alternating pulses on a wire, the other radio waves. Same information in and out, different method within the layer.

By having preset layers, it makes it easier to transmit data. For instead, at the application layer, the output from a spreadsheet is going to be different than the output from a graphic picture editor. But if the application layer says, "Just give me the information in chunks of 256bytes and I will pass it on", then any application can talk to the network. Doesn't matter what the information is, just that it is presented in 265byte chuncks (We just got through the first two layers of the model). When the data reaches the second computer, it is presented in 265byte chunks which the aplication then knows how to reassemble into either a picture or a spreadsheet.

Each of the layers handles different parts of the task of getting information from one computer to another.

Answer 2

there is a set of standards called the OSI Model which has 7 layers:
layer 1: physical
2: data link
3: network
4: transport
5: session
6: presentation
7: application

different devices and applications work at different layers
eg hub - layer 1
switch - layer 2
router - layer 3
email and IE - layer 7

Answer 3

This is a software layer used in the networking. It isn't any physical layer which you can see or used in any physical device.

Answer 4

tell you later

Answer 5

ASK MY SON