Routers are on the third layer of OSI, the network layer. OSI divides network communication work into 7 layers, namely physical layer, data link layer, network layer, transport layer, session layer, presentation layer and application layer; the purpose of the network layer is to realize the communication between two end systems. Transparent data transmission, specific functions include addressing and routing, connection establishment, maintenance and termination, etc.
#Routers belong to the third layer of the OSI architecture, the network layer.
OSI architecture means Open Systems Interconnection. The International Organization for Standardization (ISO) developed the OSI model. This model divides network communication work into 7 layers, namely physical layer, data link layer, network layer, transport layer, session layer, presentation layer and application layer. Layers 1 to 4 are considered the lower layers, and these layers are closely related to data movement. Layers 5 to 7 are higher layers and contain application-level data. Each layer is responsible for a specific job and then passes the data to the next layer.
OSI divides computer network architecture into the following seven layers:
Physical layer: Converting data into electronic signals that can be transmitted through physical media is equivalent to Porters in the post office.
Data link layer: Determines how to access the network medium.
In this layer, the data is framed and flow control is handled. This layer specifies the topology and provides hardware addressing, which is equivalent to the packing and unpacking workers in the post office.
Network layer: Rights-of-use data routing through large networks, equivalent to sorting workers in the post office.
Transport layer: Provides reliable end-to-end connections, equivalent to the letter delivery clerk running the post office in the company.
Session layer: Allows users to establish connections using simple and easy-to-remember names, which is equivalent to the secretary in the company who sends letters, writes envelopes, and opens envelopes.
Presentation layer: negotiates the data exchange format. It is equivalent to the assistant who briefs the boss and writes letters for the boss in the company.
Application layer: The interface between the user's application and the network.
Network layer
The network layer is the third layer in the OSI reference model, between the transport layer and the data link layer. It further manages the data communication in the network based on the transmission function of data frames between two adjacent endpoints provided by the data link layer, and manages to transmit the data from the source end to the destination end through several intermediate nodes, thereby forwarding the transportation The layer provides the most basic end-to-end data transfer service. The main contents include: virtual circuit packet switching and datagram packet switching, routing algorithm, congestion control method, X.25 protocol, Integrated Services Data Network (ISDN), Asynchronous Transfer Mode (ATM) and Internet interconnection principles and implementation.
The purpose of the network layer is to realize transparent transmission of data between two end systems. Specific functions include addressing and routing, connection establishment, maintenance and termination, etc. It provides services that eliminate the need for the transport layer to understand the data transmission and switching technologies in the network.
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