On the second data link layer of the network switch, its main functions include physical addressing, network topology, error checking, frame sequence, and flow control.

Physical addressing (corresponding to network addressing) defines the addressing method of devices at the data link layer; The network topology structure includes a description of the data link layer, defining the physical connection methods of devices, such as star topology or bus topology; Error checking to alert the upper layer protocol where transmission errors occur; Reorganize the data frame sequence and transmit frames other than the sequence; Flow control can delay the transmission capacity of data, so that the receiving device will not crash due to receiving information flow that exceeds its processing capacity at a certain moment.

At present, the third layer Ruijie switch also has some new functions, such as VLAN support, and link aggregation support, and even has firewall functions, which are the functions that the third layer switch has. The so-called third layer switch adds routing functionality to protocol-based VLAN partitioning.

Layer 3 switching is the key to adopting an intranet, combining the advantages of both layer 2 switches and layer 3 routers into a flexible solution that can provide line speed performance at various levels.

This integrated structure also introduces policy management attributes, which not only interconnect the second and third layers, but also provide traffic prioritization processing, security, and various other flexible functions, such as link aggregation, dynamic deployment of VLANs and intranets.