What is an interface and how does it represent a set of operations to the top level?

Question

Computer networks

Began to study the OSI network model, faced difficulties in understanding. Could you please explain to a newbie how it works. The simpler the better.

Answer 1

The simplest concept of an interface is a power outlet and a plug (or plug). Each socket has its own type of plug, for example, different countries have different standards.
And now the transmission line transmits some information (let it be a voltage of 220V), and in order to connect to this information, you need an interface from one side and the other (connectors or a plug-socket). Then the set of operations will be "plug the plug into the socket" and "switch off".
If all this is translated to the software level, then the concept of the interface can be added to "determine the type of socket", "apply power", "signal the receiver and transmitter", "reserve the load, bandwidth", etc.
Thus, the set of operations in the form of an "interface" defines those operations that the upper level can do with the lower level, without caring about the implementation of the lower level. It's like plugging a plug into a socket, and we are not interested in how the wire transfer itself works at the lower level.

Answer 2

- I studied in Bristol, Los Angeles, Priston, Columbia University, I have the title of Doctor of Medical Sciences, - the conscript answers the question of what kind of education he has.
- Write down, - says the chairman of the draft board, - the conscript can read and write!

don’t worry, learn and practice, then you will catch up with the practical, especially since in TCP / IP there are not 7, but 4 levels,
write down the question for yourself right away: why can’t you make a VPN through a proxy
and the second: how providers transmit for kilometers when the length of a twisted pair is 5th category maximum 100-180 meters
the answer to the first will help in programming life, to the second - to state that OSI understood

Answer 3

Is it fundamentally important for you to learn exactly the OSI reference model?
Just for practice, they teach the TCP / IP model, where there are four levels, not seven, it is easier there.
If there is a problem with understanding, perhaps the book should be changed.

Answer 4

Protocol - a set of rules according to which actions and information transfer takes place within one level.
Interface - the same protocol, but for communication between layers. How exactly this happens - it will not work to explain on the fingers, but if the difficulties do not scare you, start with RFC-1122 .

Answer 5

I don’t know how it can help, but I advise you to use wireshark to start studying protocols, where you can clearly see what is happening + there is a good wiki (not rfc of course ..).
I would explain it this way: 1 - always physics (hardware for receiving / transmitting a signal), 2 - logic (a certain structure is transferred from level 1 to infe, depending on the type of network (ethernet, PPP ..). Protocols are encapsulated in the second level by a level higher , for example:
browser request to the site in OSI =
7. HTTP structure
6. utf-8 or other encoding specified by a level higher
5. TLS encryption
4. TCP socket (port is specified here)
3. IP
2. Ethernet / PPPoE, etc.
1.cable/wifi rx/tx

Answer 6

What actually goes into .wp-html5vp-popup-conf ? json_encode worked correctly?