1。 A star topology network has a central node, and other nodes (workstations, servers) are directly connected to the central node. This structure takes the central node as the center, so it is also called centralized network. 2。 The characteristics of ring network topology ring structure are: each end user is connected with two adjacent end users, so there is a point-to-point link, but it always runs in one direction, so it is called upstream end user and downstream end user; The information flow in the network is fixed, and there is only one path between two nodes, thus simplifying the control of path selection. All nodes in the loop are bootstrap control, and the control software is simple; Because the information source is transmitted in series through all nodes in the loop, when there are too many nodes in the loop, it will inevitably affect the information transmission rate and prolong the response time of the network. The cycle is closed and inconvenient to expand; Low reliability, if one node fails, the whole network will be paralyzed; It is difficult to maintain and locate the faults of branch nodes.

3。 Distributed topology network has the following characteristics: due to decentralized control, even if a part of the whole network fails, it will not affect the operation of the whole network, so it has high reliability; The shortest path algorithm is used to select the path in the network, which has less online delay time and high transmission rate, but the control is complicated. Data links can be established directly between nodes, and the information flow is the shortest; It is convenient for the resources within the whole network to enjoy. Disadvantages are long connecting cable and high cost; The network management software is complex; Packet switching, path selection and flow direction control are complex; General LAN does not adopt this structure.

4。 Cellular topology Cellular topology is a common structure in wireless local area networks. It is characterized by point-to-point and multipoint transmission through wireless transmission media (microwave, satellite, infrared, etc.). ), and it is a wireless network, suitable for city network, campus network and enterprise network.