TCP/IP Detailed learning notes (1)

Here is the "TCP/IP detailed" Volume One of the notes and their own understanding of the book, I will combine the capture package software Wireshark to analyze, but due to limited conditions, can not simulate the author of the network, only simple analysis, if found wrong, please help correct.

first of all we talk about what is TCP/IP protocol:

Two hosts to communicate must follow the same specification, the messages sent to each other to know how to deal with, just like sending XML and JSON data, they need to be in a predetermined format of the organization to send, and the receiving side will be interpreted in this format. This is what the network communication protocol does, and TCP/IP is the most widely used protocol.

TCP/IP the layering makes the protocol better understood, each layer of its own, so here I look at a certain layer of the Protocol, do not control the next layer is how. For example, when we look at the TCP protocol, we do not care What the following IP is, and all you have to pay attention to is end-to-end communication, which simplifies our thinking and allows us to focus more on how this layer works.

differs from OSI model of 7 layer, TCP/IP only 4 Layer:

link layer: also known as the data Link layer or network interface layer, it is the lowest level, it contains the device driver (TCP/IP is the Ethernet driver), and the computer network card, the main processing physical details.

Network layer: processes the activity of datagrams in the network, such as routing. We use routers up to this level, and routing packet forwarding is done primarily by this layer in the router. In this layer there are mainly IP,ICMP,IGMP agreements, which we will talk about later.

Transport Layer: mainly for us to provide two host to the end of the communication. Contains reliable TCP and unreliable UDP

Application Layer: responsible for handling the details of the application.

Address in the Internet:

Each interface of the Internet must have a unique IP address, (a host can have more than one interface) Windows users can use the ipconfig command to view, Linux under the Ifconfig, long as 32bit in today's most of our IP address is dynamically allocated.

We can see that there are two interfaces in My Computer eth0 and lo where lo is the local loopback interface and the address is 127.0.0.1, which is the interface that we often walk when we connect to the local server.

This is our usual dotted decimal notation, where the number of network numbers for each class is 2, and all 0 and 1 are illegal.

Encapsulation of data:

We can see that the sender of the user data in each layer has been added to the corresponding header, and each header contains the corresponding protocol identification (described later), in this package, and the receiving end in accordance with this identification to determine which protocol, to be divided, a layer of split.

The first chapter is mainly about the TCP/IP protocol, and then we will start from the bottom up according to each layer of the corresponding protocol layer of analysis

TCP/IP Detailed learning notes (1)