- 5.1 STA Receives Strong Signals from an AP, But the Network Speed Is Slow. How Can I Locate the Problem?
- 5.2 Why Is the Association Rate Displayed on Wireless Terminals Low?
- 5.3 Why Does a STA Fail to Associate with an AP When WEP and TKIP Encryption Is Configured in 802.11n Mode?
- 5.4 The Laptop Uses the 802.11b/g NIC. How Can I Associate It with a 802.11n AP?
- 5.5 I Bought a Wi-Fi NIC. The Vendor States It Is an 802.11a/b/g/n Network Card, But Why Did I Fail to Search 5 GHz AP Signals (AP Works on Channel 149) Using This NIC?
- 5.6 Why Did STA Fail to Search 802.11n Signals After the AP Is Enabled with 802.11n?
- 5.7 Does BT Download Occupy High Bandwidth and Reduce WLAN Efficiency?
- 5.8 Does an Online 802.11b/g Terminal Affect the Rate of an Online 802.11n Terminal?
- 5.9 How Can I Separate Two STAs that Connect to the Same SSID?
- 5.10 How Do I Configure Multicast Packet Suppression to Reduce Impact of a Large Number of Low-Rate Multicast Packets on the Wireless Network?
5.1 STA Receives Strong Signals from an AP, But the Network Speed Is Slow. How Can I Locate the Problem?
- Check the number of users associated with the AP. The number of associated users cannot exceed the upper limit allowed by the AP.
- Check the channel and power of the AP. The channel and power must be set to fixed values, but cannot use default settings.
- Change the connection mode on the AP to high-speed access.
- Check whether upstream bandwidth limit is set on the AP.
- Check antennas on APs:
- The interval between the antennas on different APs cannot be smaller than 10 m.
- The interval between the antennas on the same AP cannot be smaller than 7 m.
- Use the dedicated tools to scan adjacent-channel interference. Check whether there is strong interference near the STA.
5.2 Why Is the Association Rate Displayed on Wireless Terminals Low?
This is because wireless terminals are far away from APs. As a result, radio signals are weak. In this case, the association rate that is negotiated by the wireless terminals is low. Specifically, the signal transmission rate of 802.11g APs includes 54 Mbit/s, 48 Mbit/s, 36 Mbit/s, 24 Mbit/s, 18 Mbit/s, and 12 Mbit/s.
Some wireless terminals display strong signal strength, but their actual signal strength is poor. The signal strength can be measured by using dedicated testers or test software such as wirlessmon.
The 802.11n is backward compatible with the 802.11b/g, so the 802.11n APs can be encrypted in the mode of WEP or TKIP. The association rate displayed on the STAs may be only 54 Mbit/s because the 802.11n standard does not define the WEP or TKIP encryption mode. If the 802.11n APs use the WEP or TKIP encryption mode, the STAs are associated only at 802.11g rates.
Some NICs of the STAs support only the 802.11b/g APs. When the STAs are associated with the 802.11n APs, the maximum association rate is only 54 Mbit/s. The 802.11n APs can also be configured with the 802.11b/g radio frequency type, because the 802.11n is backward compatible with the 802.11b/g.
5.3 Why Does a STA Fail to Associate with an AP When WEP and TKIP Encryption Is Configured in 802.11n Mode?
The 802.11n does not define the WEP or TKIP encryption mode. When the two encryption modes are used, STAs may fail to associate with the AP.
5.4 The Laptop Uses the 802.11b/g NIC. How Can I Associate It with a 802.11n AP?
You can associate it with 802.11n AP if the AP does not set the 802.11n-only mode. However, the signal transmission rate of the APs in 802.11b mode is low. In contrast, the time that the 802.11n APs take to transmit radio signals at 300 Mbit/s accounts for only 1/27 of the time that the 802.11b APs take to transmit radio signals. Therefore, when a comparatively large number of old wireless terminals are connected to the 802.11n APs, the AP performance decreases considerably. To ensure high performance of the entire WLAN, the 802.11b STAs will be disabled to access the network.
5.5 I Bought a Wi-Fi NIC. The Vendor States It Is an 802.11a/b/g/n Network Card, But Why Did I Fail to Search 5 GHz AP Signals (AP Works on Channel 149) Using This NIC?
5 GHz AP signals are divided into three frequency bands: low frequency (5150 MHz to 5250 MHz), intermediate frequency (5250 MHz to 5350 MHz), and high frequency (5725 MHz to 5825 MHz). China supports low and intermediate frequency bands, but the Radio Association of China authorizes the 5.8 GHz frequency. Therefore, in China, the 5 GHz AP works on radio channels that use the 5.8 GHz frequency. These optional channels include channels 149, 153, 157, 161, and 165. Many types of NICs in the market support the 5.2 GHz frequency but not the 5.8 GHz frequency. To connect your NIC to 5 GHz AP signals, you can change the AP's working channels to the channels in low and intermediate frequency bands.
5.6 Why Did STA Fail to Search 802.11n Signals After the AP Is Enabled with 802.11n?
This is because the IEEE 802.11n draft protocol does not support a high throughput rate of the WEP or TKIP unicast ciphers. If the STA uses the WEP or WPA-TKIP encryption mode, the data transmission rate will decrease to 54 Mbit/s. In WEP or TKIP mode, if the STA uses the 802.11b/g/n NIC to associate with APs, it can only be associated with 802.11g APs. As a result, the displayed signal transmission rate is 54 Mbit/s but not the 802.11n rate. This is restricted by the IEEE 802.11 standard.
5.7 Does BT Download Occupy High Bandwidth and Reduce WLAN Efficiency?
Currently, no evidence shows that the BT service reduces WLAN air interface efficiency. However, if BT users exist on the WLAN, other users feel that the network quality decreases. This is because air interface bandwidth is occupied by BT users. Therefore, user experience is poor on the WLAN with BT users.
5.8 Does an Online 802.11b/g Terminal Affect the Rate of an Online 802.11n Terminal?
Yes. 802.11b/g terminals have a low rate and occupy the air port for a longer time when forwarding the same traffic as 802.11n terminals. This lowers the rate of an online 802.11n Terminal.
5.9 How Can I Separate Two STAs that Connect to the Same SSID?
Huawei APs support Layer 2 isolation. When Layer 2 isolation is enabled, STAs cannot communicate at Layer 2. Only the upstream interface and virtual access point (VAP) interface can exchange data.
5.10 How Do I Configure Multicast Packet Suppression to Reduce Impact of a Large Number of Low-Rate Multicast Packets on the Wireless Network?
No ACK mechanism is provided for multicast packet transmission on air interfaces. In addition, wireless links are unstable. To ensure stable transmission of multicast packets, they are usually sent at low rates. If a large number of such multicast packets are sent from the network side, the air interfaces may be congested. You are advised to configure multicast packet suppression on switch interfaces connected to APs to reduce impact of a large number of low-rate multicast packets on the wireless network. Exercise caution when configuring the rate limit; otherwise, the multicast services may be affected.
Example for Configuring Multicast Packet Suppression
Create the traffic classifier test and define a matching rule.
<HUAWEI> system-view [HUAWEI] sysname SwitchA [SwitchA] traffic classifier test [SwitchA-classifier-test] if-match destination-mac 0100-5e00-0000 mac-address-mask ffff-ff00-0000 //Match the destination MAC address of multicast packets. [SwitchA-classifier-test] quit
Create the traffic behavior test, enable traffic statistics collection, and set the traffic rate limit.
[SwitchA] traffic behavior test [SwitchA-behavior-test] statistic enable [SwitchA-behavior-test] car cir 100 //Set the rate limit to 100 kbit/s. If multicast services are available, you are advised to set the rate limit according to the service traffic. [SwitchA-behavior-test] quit
Create the traffic policy test and bind the traffic classifier and traffic behavior to the traffic policy.
[SwitchA] traffic policy test [SwitchA-trafficpolicy-test] classifier test behavior test [SwitchA-trafficpolicy-test] quit
Apply the traffic policy to inbound or outbound directions of interfaces.
[SwitchA] interface gigabitethernet 0/0/1 [SwitchA-GigabitEthernet0/0/1] traffic-policy test inbound [SwitchA-GigabitEthernet0/0/1] traffic-policy test outbound [SwitchA-GigabitEthernet0/0/1] quit
