Differences between an ISO 7-layer model and an ISO 5-Layer Model

Differences between an ISO 7-layer model and an ISO 5-Layer Model

TCP/IP
The layered model (TCP/IP layering model) is also known as the Internet layered model or the Internet Reference Model (Internet
Reference Model)

ISO layer-7 Model

The Open System Interconnection model is a universal global standard developed by the International Standards Organization in 1984. It aims to create an open network system environment so that all systems can operate on each other.

The benefit of layering: each layer has a specific network function. Therefore, as long as the software and hardware are designed according to the model standard, all network components can be compatible.

1. Each layer is independent.

2. Use appropriate technologies to implement functions at the current Layer

3. Good Flexibility

4. Easy to implement and maintain

 

Layer 7 of OSI:

Layer 7 Application Layer provides network services for Applications

Presentationlayer Data Representation

Layer 5 Session Layer (sessionlayer) interconnect host communication

Layer 4 (Transport Layer) end-to-end connection

Layer 3 network layer determines the address and Optimal Path

Layer 2 data link layer (datalink layer) Media Access

Binary transfer of the first physical layer (physicallayer)

 

ISO/OSI model

Rules: data must go through 7 steps from being sent to the network, and the computer obtains data from the network to being displayed to the user, it is necessary to process data into a fixed form. However, it does not specify the method used, the technology used, and the device used for processing.

3. Role of each layer:

1) Physical Layer)
Defines a method for connecting a cable to a network card. It converts data packets sent from the data link layer into electrical signals, that is, data bits consisting of 1 and 0, and sends and receives packets through the transmission media, however, it does not have the ability to detect errors. The data unit is bit ).

L hub, repeater and cable work on this layer

 

2) data link layer)
The main function of the data link layer is to transmit packets sent from the network layer to the physical layer, because the physical layer only performs signal transmission, and there is no concept of a data framework, after the data arrives at the data link layer, it is necessary to form a framework of BIT data and control traffic and errors to ensure correctness during transmission. Encapsulate the synchronization information, verification information, and address information added to the transmitted data into data.Frame. (Data Unit) the frame header includes the warning signal, source address, and destination address.
End of data frame

L
Bridges and L2 switches work on this layer

 

3) Network Layer)
The network layer is responsible for addressing. It resolves the logical address into a physical address and determines the packet sending sequence. The unit of data transmission is grouping orPackage.

L
Routers and layer-3 switches work on this layer

 

4) Transport Layer)

The main functions of the transport layer include segment processing, re-numbering of data packets, and traffic control. segment Processing refers to splitting the data sent to the transport layer into packets suitable for the network layer, divides a piece of information into multiple data packets. Re-numbering refers to re-numbering each packet that belongs to the same information so that the receiving end can reassemble the original information in this order. Traffic control is to coordinate the speed of data sending and receiving, so as to avoid the problem that the receiving end is too late to receive because the sending speed is too fast.

Traffic control at the transport layer.

 

5) Session Layer)

It allows applications on different computers to establish connections with each other. The process of using and terminating connections is called a session. Allows users to establish, maintain, and terminate sessions between devices.

L
Data packets sent between different hosts are independent Based on the port number.

 

6) The presentation layer is mainly used for translation. Because different applications often use different syntaxes, in order to allow applications at both ends to exchange data smoothly, before sending the data, the sender must convert the data into the format of the transmission process. After arriving at the receiver end, the presentation layer of the receiver computer converts the format back.

L
Convert data into computer identifiable formats (ASCII (American standard information interchange code), ebcdic, 01 series)

 

7) Application Layer)

The application layer provides the following functions:

OSI five-layer model

TCP/IP
There are four levels in the Reference Model that correspond to the ISO Reference Model

Layer or layer. However, the ISO model does not have an Internet layer. The purpose of each layer is as follows:

Application Layer)
Level 4 Transport Layer)
Layer 3 Internet Layer)
Layer 2 network interface layer (
First Layer Physical Layer

First Layer Physical Layer

The first layer corresponds to the basic network hardware, just like the I s o Layer 7 Reference Model.

Layer 2: Network Interface Layer
The second-Layer Protocol specifies how to organize data into frames and how computers transmit frames over the network, similar to the I s o Layer 7 parameters.

The second layer of the test model.
Layer 3: Internet Layer
The layer-3 Protocol specifies the format of packets transmitted over the Internet and the transfer from one or more routers to the final destination

The packet forwarding mechanism.
Layer 4: Transport Layer
The layer-4 protocol, like the layer-4 of the I s o 7 Reference Model, specifies how to ensure reliable transmission.

Layer 5: Application Layer
The Fifth Layer Protocol corresponds to the sixth and seventh layers of the I s o Layer 7 Reference Model.

Use the Internet. Overview:
The t c p/I p protocol is organized into five conceptual layers. Although some layers in the t c p/I p Reference Model correspond to the I s o reference

One or more layers in the model. However, the I s o layering scheme does not correspond to this layer on the Internet layer.