1. Analysis of OSI seven-layer network model
Of course, we are not professionally engaged in network engineering, as long as we know which layers are there and what they are used for!
OSI seven-layer network model (from bottom to top) :
Physical layer (Physical) : Data communication between devices provides transmission media and interconnection devices, providing a reliable environment for data transmission. It can be understood as the physical media part of network transmission, such as network card, network cable, hub, repeater, modem, etc.! At this layer, the data has not been organized and is only processed as a raw bit stream or electrical voltage. The unit of this layer is: bit bit
Data link layer (Datalink) : It can be understood as a data channel. The main function is how to reliably transmit data on unreliable physical lines. The functions of changing layers include: physical address addressing, data framing, flow control, data Error detection and retransmission, etc.! In addition, this data link refers to : the physical layer provides transmission media and connections for data communication between terminal devices. Media is long-lived, and connections have lifetimes. During the lifetime of the connection, the sending and receiving ends can perform data communication one or more times. Every communication has to go through two processes of establishing communication link and dismantling communication link! This established data sending and receiving relationship ~ the devices at this layer include: network card, bridge, network switch , and the unit of this layer is: frame
Network layer (Network) : The main function is to translate the network address into the corresponding physical address, and decide how to transfer the data from the sender