Optimization of WLAN Network: the unique sword

Rivers and Lakes !!
The wireless secret that everyone is competing for-the unique nine swords are coming to the fore !!
Those who win this book can win the world!
L details:
1. Adjust the channel
Application description:
Because only some countries have opened 12 ~ 14 channels, so in general, use 1, 6, 11 channels.
 
You can adjust the transmit power of a wireless device to avoid this situation. However, in a three-dimensional plane, it is difficult to achieve zero co-frequency interference in any region in actual application scenarios.
 
However, when setting the channel, we need to consider three-dimensional signal interference, such as the left figure. Deploy three APs on the first floor. The channels from left to right are 1/6/11, respectively. At this time, the channels of the three APs deployed on the second floor should be divided into 11/1/6, similarly, the third floor is 6/11/1. In this way, the interference between floors is minimized. Both the horizontal and vertical directions allow wireless cellular coverage.
Configuration instructions:
[AC_02-wlan-ap-ap1-radio-1] channel 11
2. Adjust the antenna angle using the "sword-breaker"
Application description:
The angle of antenna coverage varies with the AP. during the installation of the device, the deviation of the antenna angle may cause some blind spots and interference with the same frequency, fine-tuning the antenna angle can improve the signal quality and reduce the interference of the same frequency.
3. Adjust the AP transmit power using the "knife-breaking" method
Application description:
We can use channels 1, 6, and 11 on a two-dimensional plane to achieve wireless deployment without interference from the same channel in any region. When the power of a wireless device is too high, the same frequency interference may occur in some areas. In this case, you can adjust the transmit power of the wireless device to avoid this situation. However, in a three-dimensional plane, it is difficult to achieve zero co-frequency interference in any region in actual application scenarios.
The WLAN system uses the CSMA/CA fair channel competition mechanism. In this mechanism, the STA first listens to the channel when sending data. If no other STA in the channel is transmitting data, first, a random backoff time is used. If no other STA can seize the channel within this time period, the STA can immediately occupy the channel and transmit data after waiting. In a WLAN system, the bandwidth of each channel is limited, and its limited bandwidth resources are evenly allocated among all Stas that share the same channel.
To avoid the same frequency interference between APs, adjust the AP power of the same channel if necessary to ensure that only one strong signal of the same channel AP is visible at the client, at the same time, it must meet the signal strength requirements (for example, not lower than-75dBm ).
Configuration instructions:
[AC_02-wlan-ap-ap1-radio-1] max-power 23
4. Adjust the beacon frame sending time in the brute-force Mode
Application description:
By default, each AP sends a Beacon packet every MS, which notifies the WLAN Network Service and synchronizes information with the wireless network adapter. Beacon messages are usually sent at the minimum rate, and the priority is relatively high. Therefore, we consider adjusting the Beacon sending interval from 160 ms to ms, which can effectively reduce the consumption of empty ports, it will be helpful for the WLAN network application of the entire building.
Configuration instructions:
[AC] wlan radio-policy radio1_y1
[AC-wlan-rp-radiopolicy1] beacon-interval 160
5. Disable Low Speed
Application description:
In a wireless WLAN Network, not all packets are sent at a fixed rate, instead, a rate set is used to send packets (for example, 11g supports 1, 2, 5.5, 11, 6, 9, 12, 18, 24, 36, 48, and 54 Mbps ), the actual wireless network adapter or AP dynamically selects a rate to send packets at these rates. Generally, the 11g bandwidth can reach the rate. It refers to the situation where all packets are sent at a rate of 54M, and it refers to the capability of an empty port channel. In fact, a large number of broadcast messages and wireless management messages are sent at a minimum rate of 1 Mbps, which consumes a certain amount of blank port resources. In the building network, the signal transmission distance is not a problem. Therefore, we consider disabling the 1, 2, 6, and 9 Mbps rates to reduce the overall occupation of blank port resources by broadcast messages and management messages.
Configuration instructions:
[AC_02-wlan-rrm] dot11g disabled-rate 1 2 6 9
6. "Cable-breaking" User Speed Limit
Application description:
The public network access bandwidth of the building has exceeded the transmission capability of the Air-port channel. If some wireless users download files through WLAN using network tools, the traffic may be very high, this directly consumes the current Space Media, resulting in slow access to the network by other wireless users, ping jitter, packet loss, and other problems. To ensure the stable operation of the WLAN Network in the building, the AC controller can limit the speed of wireless users and control the maximum bandwidth used by each user to 512 Kbps. In this way, about 10 download operations are supported in a channel space. With this function, you can properly control the impact of sudden large traffic volumes on other users in the wireless network, helping to ensure network stability and maintenance.
Configuration instructions:
Enable the wireless Speed Limit Function of the empty port to limit the maximum bandwidth of each user to 500 kbps.
 
 
7. layer-2 Isolation
Application description:
This feature allows wireless users to access gateway devices only on the AC, but not between devices. This greatly reduces the broadcast traffic of the entire building's wireless network and improves the overall performance of the building's WLAN Network. Each broadcast or group broadcast from a wireless client will broadcast a copy to all the user's APS, in addition, when a broadcast packet is sent in a space medium, the minimum rate is usually used to send the broadcast packet. Therefore, when a large number of broadcast packets are sent, the space bandwidth is occupied, this affects the network application of the entire building to a certain extent.
Configuration instructions:
For example, enable VLAN 401 user isolation to only allow users to access the MAC address of the gateway.
[AC_01] user-isolation vlan 401 enable
[AC_01] user-isolation vlan 401 permit-mac xxxx-xxxx (Gateway mac address)
"Broken Arrow" PC Power Management Properties
Application description:
Generally, the default power management attribute of the wireless network card of the PC is power-saving mode. This may cause the PC to be far away from the AP, because the transmit power is too low, the transmitted data packets are discarded or re-transmitted. Therefore, the power-saving mode of the PC is disabled. The maximum power consumption can improve the transmission power of the PC and the quality of the wireless network.
Configuration instructions:
 
 
Note: different wireless network adapters may be displayed differently.
8. Adjust the number of retransmissions of AP sent packets.
Application description:
The physical layer of the wireless WLAN Protocol has already taken into account the impact of interference and conflict. Therefore, the physical retransmission function is designed, that is, if a device sends a message that does not receive a reply ACK from the target device, the device will re-transmit the message by hardware. If the retransmission times reach the maximum, the message will be discarded. Of course, if the message is successfully sent once, it will not be re-transmitted.
By default, the number of retransmissions of the AP device is 5. You can change it to 8, which increases the probability of successful message sending when the network environment is abnormal. However, this adjustment will only increase the probability of AP sending success, and there is no way to control the NIC sending mechanism, that is, the occasional packet loss caused by environment problems from the network adapter to the AP is not greatly improved.
Configuration instructions:
[AC_02-wlan-rp-radiopolicy1] long-retry threshold 8
[AC_02-wlan-rp-radiopolicy1] short-retry threshold 8
The only thing you can do is get in and out! Both tactics are attacking and attacking the enemy has to be defended. Although only one sword is used, it is an infinite change. After learning it, the previous and later forms are integrated, and the power is greatly increased. The essence of the jianfa method is: "the enemy and the enemy are first 」.
If you are familiar with this secret, you can solve the wireless problem!

From the mortal world