Shulou(Shulou.com)06/01 Report--

1. Noun explanation:

ISO: international Organization for Standardization (International Organization for Standardization)

OSI: open Systems Interconnection (opensystem interconnection)

In the late 1970s, ISO created the OSI reference model, hoping that the networks of different suppliers can work together with each other, providing a functional framework for open interconnected information systems, but so far, this is still a great goal.

2. Upper layer and bottom layer:

The upper layer is the application layer, including the application layer and the presentation layer, and the bottom layer is the data flow layer, including the transport layer, the network layer, the data link layer and the physical layer.

3. Application layer:

The application layer is the highest layer of the OSI reference model. Its function is to realize the information exchange between application processes (such as user programs, terminal operators, etc.). Connect to the application to provide services to its process.

4. Presentation layer:

The presentation layer is the control layer of data representation, which mainly carries out special processes such as data representation, encryption and so on, so as to transform the information provided by the application layer into a form that can be understood together.

5. Session layer:

The session layer is the control layer of the session unit, which ensures the data differentiation between different applications, provides the service for the application to establish and maintain the session, and synchronizes the session.

6. Transport layer:

The transport layer mainly carries on the end-to-end IP transmission, which has the buffer function. Suppose that when two computers communicate through the network, when the quality of service of the network layer can not meet the requirements, it will improve the service to meet the requirements of the high level; when the quality of service of the network layer is good, it only carries out a very small amount of transmission work.

7. Network layer:

The network layer defines the source and destination logical addresses associated with the specified protocol and defines the path through the network. The network layer defines the procedures for the establishment and removal of network connections, as well as data transmission procedures. Among them, the communication modes of three kinds of networks are unicast, broadcast and multicast.

PS: address classification:

Unicast address: class A: 0-126 B: 128-191 C: 192-223

Multicast address: class D: 224-239

Scientific research address: category E: 240-255

127 Local Loop Code [accessing this address is equivalent to visiting yourself "

8. Data link layer:

The data link layer combines bits into bytes to form frames, accesses the media with MAC addresses, and finds errors but cannot correct them. The most common independent link product is the network card, and the bridge is also the link product. The data link layer turns intrinsically unreliable transmission media into a reliable transmission path to the network layer. In IEEE802.3, the data link layer is divided into two sublayers, one is logical link control, the other is media access control. The main functions are media access, MAC address viewing and so on (the PC side enters the cmd management interface to enter ipconfig/all to view ip and mac addresses).

9. Physical layer:

The physical layer is responsible for receiving or sending bit streams, indicating voltage or wire speed, cables, and so on. The physical layer provides transmission media and interconnection devices for data communication between devices, and provides a reliable environment for data transmission.

For more information, please refer to the entry of Baidu Encyclopedia interconnection reference model.

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