What is mesh networking?

Mesh network is a type of wireless LAN, which is a mesh structure network. In the Mesh network, all nodes are connected to each other. Each node has multiple connection channels, and all nodes form a The overall network; Mesh networking needs to comprehensively consider factors such as channel interference, hop number selection, and frequency selection.

#The operating environment of this article: Windows 7 system, Dell G3 computer.

Mesh network is a type of wireless LAN, which is a mesh structure network, also known as a "multi-hop" network. In a Mesh network, all nodes are connected to each other, each node has multiple connection channels, and all nodes form an overall network. When a certain line is blocked or unresponsive, the wireless Mesh network can select other lines for data retransmission according to the situation. Any node failure will not affect network access, and the reliability is very high; and the network can automatically repair when it fails, ensuring The WiFi network is fast and smooth.

Mesh networking requires comprehensive consideration of factors such as channel interference, hop number selection, and frequency selection. This section will take WLAN MESH based on 802.11s as an example to analyze various possible networking solutions. The following focuses on analyzing single-frequency networking and dual-frequency networking solutions and performance.

Single-frequency MESH networking

The single-frequency networking solution is mainly used in areas with limited equipment and frequency resources. It is divided into single-frequency single-hop and single-frequency multiple Jump. In single-frequency networking, the access and backhaul of all wireless access points Mesh AP and wired access point Root AP work in the same frequency band. Taking Figure 2 as an example, the channel 802.11b/g on 2.4GHz can be used Perform access and return. Depending on the product implementation method and the channel interference environment during networking, the channel used between each hop may be a completely independent interference-free channel, or a channel with certain interference (mostly the latter in the actual environment). At this time, due to interference between adjacent nodes, all nodes cannot receive or send at the same time, and the CSMA/CA MAC mechanism needs to be used for negotiation within a multi-hop range. As the number of hops increases, the bandwidth allocated to each Mesh AP will drop sharply, and the actual single-frequency networking performance will also be greatly limited.

Dual-frequency MESH networking

In dual-frequency networking, each node uses two different frequency bands for backhaul and access, such as local access services The 2.4 GHz 802.1l b/g channel is used, and the backbone Mesh backhaul network uses the 5.8 GHz 802.11a channel, so there is no interference with each other. In this way, each Mesh AP can perform backhaul and forwarding functions while serving local access users. Compared with single-frequency networking, dual-frequency networking solves the problem of channel interference in backhaul and access, and greatly improves network performance. However, in actual environments and large-scale networking, since the backhaul links use the same frequency band, there is still no guarantee that there will be no interference between channels. Therefore, as the number of hops increases, the bandwidth allocated to each Mesh AP is still There is a downward trend. Mesh APs that are far away from the Root AP will be at a disadvantage in channel access. Therefore, the number of hops in dual-band networking should also be set carefully.

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