Data segment

Introduction

In the architecture using segmented memory management, the data segment and code segment are determined before the program runs.

OSI

Data segment is a transport layer PDU.

Each layer of the OSI model encapsulates data to form a PDU (Protocol Data Unit). The PDU contains the control information added to the data at each layer of the model. These control information are usually added in the header before the data field, but may also be added in the tail. Each layer of the OSI model encapsulates data to form a PDU, and the name of the PDU varies with the information provided by the header. These PDU information is only read at the peer layer of the receiving device, and then stripped, and then the data is passed to the next layer.

The above figure shows the PDU of each layer and the control information added by each layer. This figure illustrates how to transform upper-level user data for transmission over the network. Then, the data is handed over to the transport layer, and the transport layer establishes a virtual circuit to the receiving device by sending synchronization packets. Next, the data stream is divided into small blocks, and the transport layer header is created and placed in the header before the data field. The data block at this time is called a data segment (a PDU). We can sort each data segment in order to reorganize the data stream in the sending order at the receiving end.