Wireless [WiFi] - Best Optimizing Practice 2.4GHz & 5GHz Network

This article will explain how to set up your WiFi (Wireless), using best practices to avoid WiFi interruptions and internet disconnections / slow WiFi on the internet. It shows how to configure roaming, smart steering, 802.11k/v/r, how to deal with interference, client drop-outs/disconnections, and speed issues on WiFi. It also shows what to do when you have users who cannot reach resources in the network, and if there is a high load that causes disconnection.

Disclaimer! This is an article that explains the best practice to increase performance for general WiFi environments. These suggestions might not be applicable for your specific environment if it differs from the "normal" conditions of a WiFi environment. Most of these parameters will therefore be a trial-and-error practice to find the optimal parameters for your environment. For a more accurate deployment, an active site survey is highly recommended.

Roaming

If you are experiencing that your connection at some points "freezes", if you have a hard time getting a good signal strength even though they are connected near to the Access Point (AP),  or if clients start off with a good connection, but after going to the next AP, the connection is unstable before it is lost.

These symptoms, generally speaking, are what we refer to as Roaming Issues.

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Note that a smooth roaming experience is mostly because of a good deployment and not the setting itself.  However, the configuration might help with the roaming experience. A client should be roaming when the signal strength goes below -75 dBm and the signal of a Wifi client should ideally be higher than -65 dBm wherever the clients move in the WiFi environment.

1.1 Smart Steering 

Smart Steering is used when you have more than 1 AP. This prevents "Sticky clients", which is a term used for WiFi clients that are connected to an AP (AP1), and when they move to the next AP (AP2), they do not connect to the AP2, even though the signal is better on AP2. This is because they still have a signal on AP1 (even though it's bad), the client determines that the signal is enough for internet connection.


Here we can enable Smart Steering, which forwards a client to the next available AP when the signal reaches a certain "low" level. This ensures that you have the best possible signal wherever you are in the environment. If the client gets too low signal, and there is no AP around that can give better signal, they will kick the client out of the WiFi completely. The client needs to go closer to the AP again to be able to connect.

 

1.1.1 Best Practice values (On both 2,4GHz & 5GHz)


Optimization Aggressiveness (Start setting this value to normal)

- High - the AP forwards clients more aggressively to the next AP if the client is not having a good signal

- Normal - When the signal reaches below -75 dBm, forward the client to the next AP

- Low - the AP forwards clients less aggressively to the next AP if the client is not having a good signal

 

Disassociate Station Threshold: -88 dBm

- When the signal reaches below -88 dBm, kick the client out of the WiFi and don't let it be able to connect until signal gets better then -88 dBm

1.1.2 How to configure? 

Go to Configuration -> Object -> AP Profile -> Radio -> Add/Edit Profile -> Advanced Settings

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1.2 Roaming protocols 

1.2.1 802.11r

IEEE 802.11r is a standard for fast roaming in a wireless network, also referred to as Fast BSS Transition (or Fast Roaming). Without support for 802.11r, this would require the client to re-authenticate causing issues for users (source). If you're having RADIUS / Active Directory authentication, this should be enabled. 

 

1.2.1.1 Best Practice values (On both 2,4GHz & 5GHz)

Disable 802.11r, if you're not using 802.11x (RADIUS or AD authentication) on WiFi.

1.2.2 802.11k/v

The 802.11k standard helps devices search quickly for nearby APs that are available as roaming targets by creating an optimized list of channels. When the signal strength of the current AP weakens, your device will scan for target APs from this list (source). However, the protocol isn't supported on all devices, which can lead to problems.

The 802.11v standard can direct devices to roam and can accept and respond to these Basic Service Set (BSS) Transition Management frames, leading to improved WLAN quality when connected to a network that supports 802.11v (source). However, the protocol isn't supported on all devices, which can lead to problems. 

 

1.2.3 Best Practice values (On both 2,4GHz & 5GHz)

Disable 802.11k/v, if you have roaming issues. This might be because of unsupported devices, or other issues related to the protocol.

1.2.4 How to configure

Configuration -> Object -> AP Profile -> SSID -> SSID List -> Add/Edit SSID Profile

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2. Interference (Channel Utilization)

2.1 What is interference?

WiFi Interference is a problem that occurs when two signals in the same frequency is used near each other. Think of co-channel interference (WiFi interference) as waves in the ocean when it comes from two different directions, instead of being "smooth" waves travelling, they will bump into each other and cause "collisions". In our devices, interference level is labeled as "channel utilization".

2.1.1 When do interference occur? 

Some cases might include

There is other equipment (and/or other WiFi's) nearby

If you have a microwave, or any other equipment that sends out signals on the same frequency, this will cause interference. It could also be that you are in a office building where there are a lot of companies that has their own WiFi. Their WiFi environment will reach your WiFi environment, and it will create a collision.

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When you have your two access points too close to each other

If you have two access points near each other that are operating on the same channel, it will cause a collision

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When you install the WiFi's on the floor above, and the signal "spills" onto the floor under

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2.1.2 How to check your interference level

Go to Monitor -> Wireless -> AP Information -> Radio List

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A general rule of thumb is that if you're having channel utilization over 50%, you will start having problems. If you have channel utilization over 70%, the WiFi clients will have a bad WiFi experience. If you're having channel utilization over 90%, the WiFi will be unusable for the WiFi clients. 

2.2 Speed issues

2.1.2 Channel Width

Whenever you experience a slow WiFi, this could be because of interference. To reduce the interference level (channel utilization), you can turn down the channel width . This will decrease the WiFi throughput overall, but if you have high interference levels, you will increase the throughput (speed). Channel width operates on a frequency spectrum from 20 MHz up to 160 MHz channels, higher channel width means increased maximum speeds, but also increased risk of interference.

 

2.2.1.1 Best Practice values (On both 2,4GHz & 5GHz)

If you're experiencing inconsistent speeds, WiFi disconnections etc., turn down the channel width to 20 MHz on both 2,4 GHz and 5 GHz.

2.2.1.1 How to configure Channel Width

Go to Configuration -> Object -> AP Profile -> Radio -> Add/Edit Profile

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2.2.1 Output power

A common problem will be that in order to avoid the interference, you turn down the output power of the APs. However, this will create "grey areas" in your WiFi environment where there is no WiFi connection.

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However, sometimes it is necessary to turn down the output power, because of a incorrect WiFi installation. 

2.2.1.1 Best Practice values (On both 2,4GHz & 5GHz)

Start with decreasing the output power with 3-5 dBm to the radio that has high interference (e.g. 2,4GHz) to see if this helps the interference level (See section 2.1.2 How to check your interference level). If channel utilization goes down, try to decrease it again with 2 dBm. If channel utilization stays the same, there could be other issues such as "DCS" settings (see 2.2.1 Dynamic Channel Selection (DCS) Settings).

2.2.1.2 How to configure Output Power

Go to Configure -> Wireless -> AP Management -> AP Group -> Edit AP Group 

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Radio 1 = 2,4GHz and Radio 2 = 5 GHz

2.2.3 Band Select

Band select is a function which forces clients to connect to the 5GHz band. This is because 5GHz, generally has lower interference levels, and it's also faster. The access point will try to force the clients to connect to the 5 GHz network 3 times, before it will accept the client to connect to the 2,4GHz. 

2.2.3.1 Best Practice values

If you're having high interference level (channel utilization) on 2,4GHz but good channel utilization on 5GHz, Band select might be a good option. However, some devices is not supporting band select and it might cause more problems in your network environment. Therefore, best practice is to leave this feature disabled.

2.2.3.2 How to configure Band Select

Go to Configuration -> Object -> AP Profile -> SSID -> SSID List -> Edit/Add SSID Profile 

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2.2.4 WLAN Rate Control Setting

WLAN Rate Control is the feature to let users set up the basic transmission rate of AP.

Since the management frame, broadcast, and multicast packets use the basic rate to transmit, this would impact the network performance due to the low speed.

If the network environment is well deployed (such as the signal of clients around -50 dBm to -60 dBm), configuring the higher basic rate has benefits to the network performance which include reduction of management overhead, better airtime utilization, and enhanced throughput, especially in high-AP-density scenarios.

In other words, the WLAN rate control feature is used to modify the basic transmission rate of the AP, and the rate limit feature is used to limit the transmit rate of clients connected to it (source).

2.3.4.1 Best Practice values

If you have interference issues, WLAN rate control will probably not help you with this. However, if you have a dense WiFi environment (many clients connected to the APs) and you want to increase throughput (speed) in your WiFi environment, you might change the WLAN rate control value to 6 Mbit/s for 2,4 GHz and 11 Mbit/s for 5Ghz (and 6GHz). However, increasing the WLAN rate control might create outages and disconnections for your WiFi clients if you .

2.3.4.2 How to configure WLAN rate control

There is no WLAN rate control in stand-alone mode, however, you can use the Multicast settings below to configure a basic transmission rate for multicast traffic.

Go to Configuration -> Object -> AP Profile -> Radio -> Add/Edit Profile

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Select the Multicast rate and keep the "fixed multicast rate".

Multicast Rate - if you want to deploy 4 mbit/s video streaming, select a fixed multicast rate that's higher than 4 mbit/s.

2.3 Connectivity issues

2.3.1 Dynamic Channel Selection (DCS) Settings

2.3.1.1 What is Dynamic Channel Selection? 

Dynamic Channel Selection (DCS) is among the most important wireless communication elements in dynamically changing electromagnetic environments wherein, a user can experience improved communication quality by choosing a better channel (source). In lay terms, this element is dynamically choosing the proper channel to use in the environment, by scanning the environment for the least occupied channels in that area. 

2.3.1.2 Best Practice values (On both 2,4GHz & 5GHz)

If you're having problems with interference, make sure that you have enabled DCS and that it is scheduled every night. If it's scheduled in the middle of day, this "channel selection" will be happening during office hours, which will disrupt and disconnect all users at that time of channel selection. Also, if the DCS time interval is set, you have no control over the time when the DCS is happening, thus, it can disrupt the WiFi in the middle of the day. 

The best practice for DCS is therefore to enable DCS schedule to the middle of the night, disable DCS client aware, disable Avoid 5F DFS channel (if there's no airport/seaport/military base/weather stations, etc. nearby the WiFi environment) and set 2.4Ghz channel deployment to "All available channels" - if you're having high interference level (channel utilization).

2.3.2 Intra-BSS traffic blocking - Cannot reach devices in my network

Intra-BSS Traffic Blocking makes sure that the wireless clients cannot talk to each other and is an important part of the Layer 2 isolation. When this is enabled, the device (e.g. Chromecast) won't be able to talk to the mobile phone, laptop or any other clients in the network which will prevent the connection to be established (read more here). Best practice for Intra-BSS Traffic Blocking is to only enable this for Guest WiFi's that is for clients that you don't trust.

2.3.2.1 How to disable Intra-BSS Traffic Blocking

  • Make sure Intra-BSS Traffic Blocking is disabled under
Configuration -> Object -> AP Profile -> SSID -> SSID Profile

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  • Make sure you don't have Layer 2 isolation enabled under
Configuration -> Network -> Layer 2 isolation

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2.3.3 Unsecure network - WPA2/WPA3 standard

If you're having problems with devices not trusting a WiFi, you might want to increase the WPA-standard to WPA3, or change the password of a WPA2 encryption to a strong password. 

A strong password consists of:

- at least 12 length of password

- at least one upper case letter

- at least one lowercase letter

- at least one number

- at least one special character

2.3.4 Load Balancing

If you're having users kicked out from the WiFi, when there's a little higher load than usual. It could be useful to configure Load Balancing to balance out the clients when the load gets too high. 

Utilize the Load Balancing function to control the number of devices connected.

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