Malong and wireless network optimization

 

1. Problems in the Early Stage: a large number of users use wireless networks, and a large range of wireless APs are down. The wireless network latency is too high and frequent disconnection occurs. 1.1 Cause Analysis in the early stage of the new office, because there is no sufficient time to test the optimization network, all Wireless AP for the Tp-link841N household type), and no Wireless AP channel division, the deployment location also has some drawbacks. As a result, the Wireless AP is continuously down and the bandwidth throughput of the Wireless AP is reduced. 1.2 initial Wireless AP signal test:

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The signal strength is relatively weak, and the stable information is also relatively poor. Network disconnection and high network latency often occur. According to the above troubleshooting causes, first, the system O & M department personnel agreed that there was a problem with the channel division, and the Wireless AP channels with the same ssid must be more than 5 transmit power intervals of 25 MHz ). After adjustment, it was found that the wireless performance was still poor and the expected goal could not be achieved. 1.3 Under the Guidance of the Technical Director, there must be rules for wireless deployment locations: The frequency selected in the same region should be at least 25 MHz apart, we can use three non-overlapping channels, such as channels 1, 6, and 11 ). Select different channels for the adjacent AP, and ensure that there are other AP devices with different channels selected for the same channel number. When considering the signal coverage between APs, we must consider not only the channel difference settings at the horizontal layer, but also the channel difference settings at the vertical layer. This is the case during floor construction, special considerations should be taken into consideration. If many APs are required in some special environments and the channels cannot be completely separated, you can reduce the transmit power and interference of the AP. 1.3.1 channel release:

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After the adjustment, the effect was further improved, but it was found that there were still problems. The wireless bandwidth throughput was very general, the speed of using wireless file transmission between Intranet and Intranet was very low, and the packet loss rate was very high. In response to the above problems, we further analyzed the problem and consulted the vendor's customer service to obtain technical support. The vendor's related technologies did not provide a satisfactory solution. 2. Seek foreign aid --- more advanced equipment & adventure flash machine 2.1 Cisco equipment suppliers provide Cisco professional wireless equipment. However, they can only find a third-party company to provide professional wireless equipment cisco equipment), deploy it on the first layer, and test the software. Compared with the home-type Wireless AP Tp-link841n, wireless stability, bandwidth throughput capacity has been greatly improved. 2.2 adventure brush machine, not becoming a kernel will become a brick before this listen to tie Gang said that someone on the Internet brush 841N machine, so the Internet access to relevant information, relatively fire dd-wrt, many routing systems in the Forum need to download the Forum currency, helpless, only through the system name in Google search to find the dd-wrt official website http://www.dd-wrt.com ), find the bin upgrade file supporting Tp-link 841n for download. 2.2.1 after obtaining a Tp-link 841N during the upgrade process, initialize it first. After initialization, log on to Tp-link 841 N, click system tools, and select Software Upgrade

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Click Browse to find the corresponding upgrade package, and click upgrade

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After Upgrade, Tp-link841N restarts automatically, login DD-wrt

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I will not write more wireless settings here. 2.2.2 I tested the stability after the flash. 2.2.2.1 use QQ to transmit data between internal networks

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2.2.2.2 a large number of wireless users connect to the Wireless AP

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In my computer, ping www.baidu.com to test ,:

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The 215ping packet is sent, 214 is received, and 1 is lost. The minimum response is 4 ms, the maximum response is 194 ms, and the average is 23 ms. Compared with the previous Wireless AP, the performance is improved by N times, the dd-wrt system supports embedded linux systems with open system interfaces. It supports multi-language, scheduled restart tasks, and radio servers, you can change the wan port to a switch port, telnet, or ssh ...... More features will not be described here, waiting for you to discover. 3. From an economic point of view, the price of a professional Wireless ap is about 3 K, the price of an ap controller is about 30 K, and that of a household Wireless ap is about K. The pony can also drive the car, but its stability and security need to be verified. We recommend that you use professional wireless devices in large projects. Vendors with high stability, security, and ease of management are all well-designed for our consumers. 4 Appendix: 4.1 frequency of transmitting Wireless AP Channels

Channel ID	Center Frequency	Low-end channel/high-end frequency
1	2412 MHz	2401/2423 MHz
2	2417 MHz	2411/2433 MHz
3	2422 MHz	2416/2438 MHz
4	2427 MHz	2421/2443 MHz
5	2432 MHz	2426/2448 MHz
6	2437 MHz	2431/2453 MHz
7	2442 MHz	2431/2453 MHz
8	2447 MHz	2436/2458 MHz
9	2452 MHz	2441/2463 MHz
10	2457 MHz	2446/2468 MHz
11	2462 MHz	2451/2473 MHz
12	2467 MHz	2456/2478 MHz
13	2472 MHz	2461/2483 MHz

4.2 WLAN loss caused by common obstacles

Barrier	Attenuation Q) (DB)
Light Wall)	5 ~ 8 dB
Panel wall 5 ~ 10 cm)	5 ~ 6 dB
Middle Wall Midium Wall)	10dB
Heavy Wall)	15 ~ 20 dB
Overweight Wall Very Heavy Wall)	20 ~ 25dB
Glass windows contain metal oxides)	5 ~ 8 dB
Glass windows do not contain metal oxides)	3 dB
Solid ceiling)	15 ~ 20 dB
Ceiling thickening)	20 ~ 25dB

The empirical value of Power Attenuation Caused by parameters in the table is GHz radio wave penetration barrier. It can be used as a reference for wireless signal coverage judgment in actual projects. It can be seen that for the inside of a building, the signal attenuation of brick walls and reinforced concrete walls is particularly large, while the signal attenuation of boards and glass is relatively small. Generally, the wireless signal of the AP can penetrate a solid wall. Whether the AP can penetrate the second wall depends on the wireless network card and wall of the client.

This article is from the "Scan targets" blog. For more information, contact the author!