Understanding the OSI Model Using Logistics

Author | Qiongyu Zhuguang

Produced by | Automotive Electronics and Software

This article will introduce the OSI model layer by layer corresponding to each link of logistics and transportation, such as the physical layer is similar to transportation tools, the data link layer is like cargo loading and fixing, and the network layer corresponds to transportation route planning. Data is encapsulated and transmitted layer by layer in the OSI model, analogous to the cargo from packaging and loading to transportation according to the route and delivery for use. The specific correspondence between the functions of each layer and the logistics links shows the similarities between the two in structure and function, providing a new perspective for understanding complex systems.

OSI Model: The OSI (Open Systems Interconnection) model is divided into seven layers, namely the physical layer, data link layer, network layer, transport layer, session layer, presentation layer and application layer. Each layer has its own specific functions and provides services for the upper layer while relying on the support of the lower layer.

Logistics and transportation: It can be compared to the various links of logistics and transportation. For example, the most basic is the means of transportation (equivalent to the physical layer), and above that is the loading and fixing method of the goods (similar to the data link layer, ensuring the correct placement of the goods on the means of transportation), and above that is the transportation route planning (similar to the network layer, determining the transportation path of the goods), the scheduling and management during the transportation process (similar to the transport layer, ensuring that the goods are transported as planned), the coordination and arrangement of the handover of goods (similar to the session layer, determining the rules and time of the handover, etc.), the packaging and identification of the goods (similar to the presentation layer, allowing the recipient to correctly identify the goods), and the final delivery and use of the goods (similar to the application layer, the use of the goods after arriving at the destination).

OSI model : In the OSI model, data starts from the application layer at the sender, is encapsulated at each layer (adding the header and tail information of that layer), and then is transmitted to the receiver through the physical medium. The receiver then starts from the physical layer, decapsulates each layer, and finally sends the data to the application layer. For example, at the network layer, information such as the source IP address and the destination IP address is added to the data so that the correct path can be found in the network.

Logistics and transportation : In logistics and transportation, the goods start from the place of shipment and are first packaged and loaded (encapsulated), and then transported according to the transportation route (similar to the network path). During the transportation process, there will be a choice of transportation tools (such as trucks, ships, etc., similar to the choice of physical media for data transmission). The goods will pass through multiple transfer stations (similar to nodes in the network) for scheduling and management during transportation. After arriving at the destination, the goods will be unloaded and unpacked (unsealed), and finally delivered to the user.

4.1 Physical Layer (OSI) and Transportation Tools (Logistics)

OSI physical layer : mainly responsible for transmitting the original bit stream on the physical medium, involving the characteristics of the physical medium, such as the type of cable, the specification of the optical fiber, the frequency band of the wireless signal, etc. It defines the mechanical, electrical, functional and procedural characteristics of the physical interface.

Logistics transportation tools : such as the body structure of trucks, the track specifications of trains, the hull size and carrying capacity of ships, etc., these are all physical foundations. Just as the physical layer stipulates the physical basis for data transmission, transportation tools provide physical carriers for cargo transportation. Moreover, different transportation tools are suitable for different transportation scenarios, such as small trucks are suitable for short-distance urban distribution, and large ships are suitable for ocean transportation of bulk commodities.

4.2 Data Link Layer (OSI) and Cargo Loading and Securing (Logistics)

OSI Data Link Layer : Organizes the raw signals received by the physical layer into frames, performs error detection and correction, and identifies different devices in the network through MAC (Media Access Control) addresses to ensure the correct transmission of data between adjacent nodes.

Logistics cargo loading and securing : In logistics, cargo loading and securing is like a data link layer function. It is necessary to ensure that the cargo is properly placed on the transport vehicle to prevent damage or loss during transportation. For example, use ropes to secure the cargo, place the cargo on appropriate shelves, and record the cargo's location information on the transport vehicle (similar to the MAC address, used to identify the cargo's location in the "local network" of the transport vehicle).

4.3 Network Layer (OSI) and Transport Route Planning (Logistics)

OSI Network Layer : Responsible for sending data packets from the source node to the destination node. Its main functions include addressing (IP address), routing selection, and packet forwarding. It selects the best transmission path based on the network topology and status.

Logistics and transportation route planning : In logistics, transportation route planning should consider factors such as the starting point and end point, the cities or ports passed through, traffic conditions, and transportation costs. Just as the network layer selects the best path based on information such as IP addresses, logistics route planning should determine the optimal transportation route based on the starting point, end point, and various constraints of the goods to ensure that the goods can reach the destination efficiently and safely. For example, when choosing an express delivery route, factors such as the distribution of the express company's transfer centers and the degree of transportation convenience should be considered.

4.4 Transport layer (OSI) and scheduling and management during transportation (logistics)

OSI transport layer : mainly provides end-to-end communication services, distinguishes different applications through port numbers, and implements reliable transmission (such as TCP protocol) or unreliable transmission (such as UDP protocol). It ensures that data arrives at the destination in the correct order and quality.

Scheduling and management in the process of logistics transportation : In the process of logistics transportation, the scheduling and management departments must ensure that the goods arrive at the destination on time and in order. For example, for vehicle transportation, it is necessary to arrange the driver's working hours and rest time, and monitor the driving status of the vehicle; for multimodal transportation, it is necessary to coordinate the connection between different modes of transportation, such as the transfer between trucks and trains, and between trains and ships. Just like the transport layer must ensure the reliable transmission of data, the scheduling in the process of logistics transportation must ensure the smooth transportation of goods.

4.5 Session layer (OSI) and coordination of cargo delivery (logistics)

OSI Session Layer : Responsible for establishing, maintaining and managing sessions, including session establishment, teardown and synchronization during sessions. It ensures that both parties can exchange data effectively.

Coordination and arrangement of cargo handover in logistics : In logistics, cargo handover is a key link. It is necessary to coordinate the time, place and method of handover between the shipper, the transporter and the consignee. For example, in the process of loading and unloading cargo at the port, it is necessary to coordinate the work of the shipping company, the terminal loading and unloading company and the consignee to determine the time when the cargo is unloaded from the ship, the location where it is placed, and the time when the consignee picks up the cargo, etc. This is similar to the coordination and management of the session at the session layer.

4.6 Presentation Layer (OSI) and Packaging and Labeling of Goods (Logistics)

OSI Presentation Layer : Mainly deals with data representation, conversion, and encryption. For example, data is converted from one encoding format to another, or data is encrypted and decrypted to ensure that data is correctly understood and securely transmitted between different systems.

Packaging and labeling of logistics goods : In logistics, the packaging and labeling of goods play a similar role. There will be various labels on the packaging of goods, such as the name, quantity, weight, place of shipment, place of receipt, barcode or QR code, etc. These labels allow staff at different stages to correctly identify the goods and operate according to the instructions on the packaging. For example, there will be special labels on the packaging of fragile goods to remind staff to handle them carefully; by scanning the barcode, detailed information of the goods can be obtained, which is similar to the representation and conversion function of the presentation layer for data.

4.7 Application Layer (OSI) and Goods Delivery and Use (Logistics)

OSI application layer : It is the interface between users and the network, providing various network application services, such as email, file transfer, web browsing, etc. It is the functional layer directly used by users.

Logistics delivery and use of goods: In logistics, after the goods are delivered to the user, the user begins to use the goods, which is equivalent to the function of the application layer. For example, after the goods purchased by the user arrive through logistics transportation, the user can open the package and use the goods, just like in the network, users use data through the application layer services.

This table should help to more clearly understand the similarities between data transmission and logistics transportation processes, providing a new perspective for understanding complex systems.