TCP/IP Study Notes-Overview

TCP/IP protocol families are divided into four layers: link layer, network layer, transport layer, and application layer.

Each layer is responsible for different functions:
1) link layer, also known as data link layer or network interface layer,
It usually includes the device drivers and computers in the operating system.
Network interface card. They work together with the physical interface details of the cable (or any other transmission medium.

2) the network layer, also known as the Internet layer, Processes Group Activities in the network, such as group routing. In
In the TCP/IP protocol family, the network layer protocol includes the IP protocol (Internet Protocol) and ICMP protocol (Internet Control
Protocol) and ICMP protocol (Internet Group Management Protocol ).

3) the transport layer provides end-to-end communication for applications on two hosts. In the TCP/IP protocol family, there are two
Different transmission protocols: TCP (Transmission Control Protocol) and UDP (User Datagram Protocol ).
TCP provides high-Reliability Data Communication for two hosts. The work it does includes the data points that the application delivers to it.
Send a suitable small block to the following network layer, confirm the group received, and set the timeout clock for the last confirmation group.
. Because the transport layer provides high-reliability end-to-end communication, the application layer can ignore all these details.
On the other hand, UDP provides a very simple service for the application layer. It only refers to the group called a datagram.
A data packet is sent from one host to another, but it is not guaranteed that the data packet can reach the other end. Any required reliability
Must be provided by the application layer.
The two transport layer protocols have different purposes in different applications, which will be seen later.

4) the application layer is responsible for handling specific application details. Almost all different TCP/IP implementations provide the following
Common applications:
• Telnet Remote logon.
• FTP file transfer protocol.
• SMTP Simple Mail Transfer Protocol.
• SNMP Simple Network Management Protocol.

In TCP/IP, the difference between the network layer and transport layer is the most critical: the network layer (IP) provides point-to-point services,
The transport layer (TCP and UDP) provides end-to-end services.

An Internet is a network. The common cornerstone of constructing the Internet is routers, which connect networks to one at the IP layer.
. The Internet with the first letter in uppercase refers to the large Internet distributed all over the world, including more than 10 thousand networks and
Over 1 million hosts.

On the Internet, each interface is identified by an IP address, although you are used to using a host name rather than an IP address.
The domain name system provides dynamic ing between host names and IP addresses. The port number is used to identify applications that communicate with each other. Server
The server uses a well-known port number, while the customer uses a temporary port number.