What Is a LAN Network Diagram?

The network topology refers to the physical layout of interconnecting various devices with transmission media (there are multiple methods for interconnecting various devices participating in the work of the LAN with media, but in fact there are only a few ways that are suitable for the work of the LAN).

The network topology diagram refers to a network structure diagram composed of network node devices and communication media.

Chinese name: Network topology diagram
Foreign name: Network Topology

Nature: Use transmission media to interconnect various equipment physical layouts
Structure: Star structure, ring structure, etc.
Purpose: Connection structure diagram of computers and other equipment in the network

Introduction to network topology diagram

Network topology refers to the physical layout of interconnecting various devices with transmission media, which is how to connect computers and other devices in the network. The topology diagram shows the network configuration and connection between network servers and workstations. Its structure mainly includes star structure, ring structure, bus structure, distributed structure, tree structure, network structure, honeycomb structure, etc. ^[1]

Network nouns

Network topology graph nodes

A node is a network element. The network unit is various data processing equipment, data communication control equipment and data terminal equipment in the network system.

Nodes are divided into: transfer nodes, whose role is to support network connections, which transfer and transfer information through communication lines; access nodes, which are the source and destination of information exchange.

Network topology diagram link

A link is a connection between two nodes. There are two types of links: "physical link" and "logical link". The former refers to the actual communication connection and the latter refers to the network path that functions logically. Link capacity refers to the maximum amount of information that each link can accept in a unit of time.

Network topology path

A path is a series of nodes and links from a node that sends information to a node that receives information. In other words, it is a series of node-to-node links established across communication networks.

Network topology graph classification

Network topology diagram star topology

The star structure is the oldest connection method, and the phones that everyone uses every day belong to this structure. The star structure means that the workstations are connected to form a network in a star mode. The network has a central node, and other nodes (workstations, servers) are directly connected to the central node. This structure is centered on the central node, so it is also called a centralized network.

This structure facilitates centralized control because communication between end users must pass through a central station. Because of this feature, it also brings advantages such as easy maintenance and safety. When the end user equipment is down due to a failure, it will not affect the communication between other end users. At the same time, its network delay time is small and transmission error is low. However, this structure is very disadvantageous in that the central system must have extremely high reliability, because once the central system is damaged, the entire system tends to be paralyzed. For this reason, the central system usually adopts dual-machine hot backup to improve the reliability of the system. ^[1]

Network topology diagram ring network topology

The ring structure is often used in a LAN. The transmission media in this structure goes from one end user to another end user until all end users are connected in a ring shape. Data is transmitted between nodes in one direction in a loop, and information is passed from one node to another. This structure obviously eliminates the dependence on the central system when the end user communicates.

The characteristics of the ring structure are: each end user is connected to two adjacent end users, so there is a point-to-point link, but it always operates in a unidirectional manner, so there are upstream and downstream users. Information flow in the network along a fixed direction, two nodes have only one road, which simplifies the control of path selection; each node on the loop is bootstrap control, so the control software is simple; because the information source is in The loop passes through each node serially. When there are too many nodes in the loop, it will inevitably affect the information transmission rate and extend the response time of the network. The loop is closed, which is not easy to expand. Will cause the entire network to be paralyzed; maintenance is difficult, and it is difficult to locate branch node faults. ^[1]

Network topology diagram bus topology

The bus structure is a way to use the same medium or cable to connect all end users, that is, the physical media connecting the end users is shared by all devices, the workstations are equal, there is no central node control, and the information on the common bus is mostly baseband. Formal serial transmission, its transmission direction always spread from the node sending the information to both ends, just like the information transmitted by a broadcast station, so it is also called a broadcast computer network. Each node performs an address check when receiving information to see if it matches the address of its workstation, and if it matches, it receives information from the Internet.

One issue that must be addressed using this structure is to ensure that end users cannot conflict when sending data using media. In point-to-point link configuration, this is fairly straightforward. If this link is half-duplex operation, only a simple mechanism is needed to ensure that the two end users work in turn. In the one-to-multipoint method, the access to the line is determined by the inquiry of the control end. However, in a LAN environment, since all data stations are equal, the above mechanism cannot be adopted. In this regard, a media access method used in a bus-sharing network was studied: carrier-sense multiple access with collision detection, abbreviated as CSMA / CD.

This structure has the advantages of low cost, flexible access of the data end user to the network, and the failure of the site or one end user does not affect the communication of other sites or end users. Disadvantages are that only one end user can send data at a time, and other end users must wait to obtain the transmission right; the media access acquisition mechanism is more complicated; maintenance is difficult, and branch node fault finding is difficult. In spite of the above-mentioned shortcomings, due to the simple wiring requirements and easy expansion, end-user failures, additions and deletions will not affect the work of the entire network, so it is the most commonly used in LAN technology. ^[1]

Network topology diagram distributed topology

A distributed structure network is a form of network that interconnects computers distributed in different locations through lines.

The distributed structure network has the following characteristics: due to the use of decentralized control, even if a local failure in the entire network does not affect the operation of the entire network, it has high reliability; the shortest path algorithm in the network path selection Therefore, the online delay time is small, the transmission rate is high, but the control is complicated; data links can be directly established between each node, and the information flow is the shortest; it is convenient for resource sharing across the network. Disadvantages are the long cables used to connect the lines, high cost, complicated network management software, complex packet switching, path selection, and flow direction control; this structure is not used in general local area networks.

Network topology diagram tree topology

The tree structure is a hierarchical centralized control network. Compared with the star, it has a short total length of communication lines, low cost, easy expansion of nodes, and convenient path finding. However, in addition to leaf nodes and their connected lines, Failure of a node or its connected lines will affect the system.

Network topology

In a mesh topology, there is a point-to-point link connection between every device on the network. This connection is not economical. This method is used only when each site needs to send information frequently. Its installation is also complicated, but the system has high reliability and strong fault tolerance. Sometimes called a distributed structure.

Network topology diagram

The cellular topology is a structure commonly used in wireless local area networks. It is characterized by point-to-point and multipoint transmission of wireless transmission media (microwave, satellite, infrared, etc.), and is a wireless network suitable for urban networks, campus networks, and enterprise networks.

Network topology diagram hybrid topology

Hybrid topology is a network structure that combines a star structure or a ring structure and a bus structure. Such a topology structure can better meet the expansion of larger networks and solve the limitations of the star network on the transmission distance. The limitation of the number of users connected by the bus network is solved.

Advantages of hybrid topology: It is widely used, it solves the shortcomings of star and bus topology, and meets the actual needs of large company networking. Expansion is quite flexible. Faster speed: Because its backbone network uses high-speed coaxial or optical cables, the speed of the entire network should not be too limited. The disadvantage is that because the broadcast message transmission method is still used, the bus length and the number of nodes are also limited. Weaknesses that also have a bus-type network structure where the network speed will decrease as the number of users increase. It is difficult to maintain, which is mainly restricted by the topology of the bus-type network. If the bus is broken, the entire network will be paralyzed.

Network topology diagram mainstream and advantages and disadvantages

title There are three topologies used by most LANs:

Network topology diagram star topology

The main advantages of a star topology are:

1. Simple structure, easy to manage and maintain;

2. Flexible reconfiguration;

3. Convenient fault detection and isolation;

4. Simple control, easy to build network;

5. The network delay time is small, and the transmission error is low;

The main disadvantages of the star topology are:

1. High cost and low reliability;

Network topology diagram ring topology

The advantage is that because each node is connected to one node in both directions at the same time, this path cannot be connected to each other, so the ring topology has natural fault tolerance. The disadvantage is that because there are data flows from two directions, the two directions must be distinguished or restricted to avoid the indistinguishable redundant data flow from interfering with normal communication. Management and maintenance are complex.

Network topology diagram bus topology

The advantages are simple structure and good scalability. The disadvantage is that maintenance is difficult, and a single point structure may affect the entire network.