This is my little understanding of computer network, the problem is in the below:

personal understanding:
Computer network is actually to the process of communication between two hosts, is to see a public resource, but due to the complexity of network have the agreement as a constraint, to standardize the process
A, the agreement from the top down, the five layer model) : (I use the book
1, the application layer: in fact is in order to achieve the ultimate goal, see the same resources among process
A simple example: (1) is like a call, is you say first I finished, I just can say, can still get in a word,
(2) the Shared memory, call the SHMCTL, realize the operation of the communication, and shmat is actually the agreement below things
This layer of agreement: the main specification is communication problem, and set up a communication is the following things

2, the transport layer: in order to establish communication links between two processes (find two processes and connection is established, with no specific communication)
The agreement is: how to find a process between two hosts, this time is

3, the network layer: in order to establish communication between two hosts (find two hosts and establish a connection, but there is no specific communication)
Protocol: so IP to find the network, and ARP protocol through the IP address to find the corresponding host
Equipment: routing: find target in forwarding network

4, the link layer: in order to make the binary frame (bittorrent) become
Bit become a data frame agreement: is a specification
Equipment: switch: to increase the number of interfaces, to expand a network, network or LAN

5, the physical layer: this is the hardware
Protocol: a specification for transmission bitstream, how to transmit the bitstream
Equipment: hub: in order to expand bit signal

In fact, for the whole transmission process, only have cables, hubs, switches, routers it several hardware
Network protocols in three layer, which is how to add header, how to deal with this header, where done with hair

Second, the agreement is how to select
But each layer of the protocol is various, how to select the agreement?
(1) for the link layer to choose according to hardware agreement
(2) for the three layers, according to actual needs to choose agreement

here is my question:
1,
(1) how packets encapsulation and stripping, actually how to forward is the core of the agreement
(2) the understanding of the accord, actually is to task for a layer on the macro task specification, how to do, what is the specific process,
(3, but the actual software to complete the software to do the actual encapsulation, stripping
I don't know whether this understanding, isn't that right, software to complete, how the book just about hubs, switches, routers these hardware, there is no practical software,
The hardware is part of the agreement?

2, the receiving party, each layer of the receiver is actually don't know what the sender is the use of the agreement, just according to and stripping header information to extract the information packet, I don't know right

The sender: 3 is based on their hardware conditions and requirements to complete the datagram encapsulation
Then is to complete the task of the encapsulation process is only saved several encapsulation scheme, according to the need to make a choice, I don't know right
4, can have a look at the place where I have the above understanding deviation, the score is a little less

CodePudding user response:

This system have a look at a book on TCPip

CodePudding user response:

1. Integrity of the outer part of the message is usually encapsulated by system () when you call the corresponding method, but also can be naked package,
2. The message is a byte stream, Ethernet packets from outside to inside is Ethernet, IP (or PPP) head, TCP, the application protocol head, flow content, but application protocol may be nested,
3. No matter who, the whole message from outside to inside has always been the TLV nested, T is the type, L is the length, V is the Value, here said the TLV not after T L and V, and fixed length, but according to the agreement, the etheric head is known and default, peripheral to will by parsing,
Under a wireshark, you just grab a package, there should be a HTTP packet control message to see me,

CodePudding user response:

Both cable and wireless communication, first of all must be bearing information of the carrier, the carrier to convey information, such as wireless communication, combined with the changes in the way such as wave amplitude of the sequence to represent a set of information, cable by alternating current (ac) level changes the combination of the way to show some information, such as how to some of our sound image text carrier transmitted over here? Process of communication, communication machine, man-machine communication, everyone's communication, communication between human and nature is coding decoding process, to explore the nature, is in understanding the nature of the coding,