The following figure provides an example of a WiFi network.

A station or WiFi client is any WiFi-capable device that can connect to an AP using a WiFi signal.

Dynamic Channel Selection (DCS) is a feature that allows an AP to automatically select the radio channel which it broadcasts. For more information, see Technical Reference.

Wireless load balancing is the process where you limit the number of connections allowed on an wireless access point (AP) or you limit the amount of wireless traffic transmitted and received on it so the AP does not become overloaded.

Use this screen to manage the Zyxel Device’s general WiFi settings.

Each field is described in the following table.

Use this screen to enable Rogue AP Detection and import/export a rogue or friendly AP list in a txt file.

A rogue AP is a wireless access point operating in a network’s coverage area that is not under the control of the network administrator, and which can potentially open up holes in a network’s security.

In the following example, a corporate network’s security is compromised by a rogue AP (RG) set up by an employee at his workstation in order to allow him to connect his notebook computer wirelessly (A). The company’s legitimate WiFi network (the dashed ellipse B) is well-secured, but the rogue AP uses inferior security that is easily broken by an attacker (X) running readily available encryption-cracking software. In this example, the attacker now has access to the company network, including sensitive data stored on the file server (C).

If you have more than one AP in your WiFi network, you should also configure a list of “friendly” APs. Friendly APs are wireless access points that you know are not a threat. It is recommended that you export (save) your list of friendly APs often, especially if you have a network with a large number of access points. Exported lists show MAC addresses in txt file format separated by line breaks.

This feature allows the Zyxel Device to monitor the WiFi signals for other wireless APs (see also Radio Frequency (RF) Monitor). Detected APs will appear in the Monitor > Wireless > Detected Device screen, where the Zyxel Device will label APs with the criteria you select in Suspected Rogue AP Classification Rule as a suspected rogue. The APs which you mark as either rogue or friendly APs in the Monitor > Wireless > Detected Device screen will appear in the Wireless > Rogue AP screen. See Zyxel Device Product Feature Comparison to know which models support Rogue AP Detection.

Each field is described in the following table.

Each field is described in the following table.

Use this screen to configure wireless network traffic load balancing between the APs on your network (see Load Balancing ).

Each field is described in the following table.

When your AP becomes overloaded, there are two basic responses it can take. The first one is to “delay” a client connection. This means that the AP withholds the connection until the data transfer throughput is lowered or the client connection is picked up by another AP. If the client is picked up by another AP then the original AP cannot resume the connection.

For example, here the AP has a balanced bandwidth allotment of 6 Mbps. If laptop R connects and it pushes the AP over its allotment, say to 7 Mbps, then the AP delays the red laptop’s connection until it can afford the bandwidth or the laptop is picked up by a different AP with bandwidth to spare.

The second response your AP can take is to disassociate with clients that are pushing it over its balanced bandwidth allotment.

Connections are cut based on either idle timeout or signal strength. The Zyxel Device first looks to see which devices have been idle the longest, then starts kicking them in order of highest idle time. If no connections are idle, the next criteria the Zyxel Device analyzes is signal strength. Devices with the weakest signal strength are kicked first.

Use this screen to configure dynamic radio channel selection (see Dynamic Channel Selection (DCS) ).

Each field is described in the following table.

The following section contains additional technical information about the features described in this chapter.

When numerous APs broadcast within a given area, they introduce the possibility of heightened radio interference, especially if some or all of them are broadcasting on the same radio channel. If the interference becomes too great, then the network administrator must open his AP configuration options and manually change the channel to one that no other AP is using (or at least a channel that has a lower level of interference) in order to give the connected stations a minimum degree of interference. Dynamic channel selection frees the network administrator from this task by letting the AP do it automatically. The AP can scan the area around it looking for the channel with the least amount of interference.

In the 2.4 GHz spectrum, each channel from 1 to 13 is broken up into discrete 22 MHz segments that are spaced 5 MHz apart. Channel 1 is centered on 2.412 GHz while channel 13 is centered on 2.472 GHz.

Three channels are situated in such a way as to create almost no interference with one another if used exclusively: 1, 6 and 11. When an AP broadcasts on any of these 3 channels, it should not interfere with neighboring APs as long as they are also limited to same trio.

However, some regions require the use of other channels and often use a safety scheme with the following four channels: 1, 4, 7 and 11. While they are situated sufficiently close to both each other and the three so-called “safe” channels (1,6 and 11) that interference becomes inevitable, the severity of it is dependent upon other factors: proximity to the affected AP, signal strength, activity, and so on.

Finally, there is an alternative four channel scheme for ETSI, consisting of channels 1, 5, 9, 13. This offers significantly less overlap that the other one.

Because there is a hard upper limit on an AP’s wireless bandwidth, load balancing can be crucial in areas crowded with wireless users. Rather than let every user connect and subsequently dilute the available bandwidth to the point where each connecting device receives a meager trickle, the load balanced AP instead limits the incoming connections as a means to maintain bandwidth integrity.

There are three kinds of wireless load balancing available on the Zyxel Device:

Load balancing by station number limits the number of devices allowed to connect to your AP. If you know exactly how many stations you want to let connect, choose this option.

For example, if your company’s graphic design team has their own AP and they have 10 computers, you can load balance for 10. Later, if someone from the sales department visits the graphic design team’s offices for a meeting and he tries to access the network, his computer’s connection is delayed, giving it the opportunity to connect to a different, neighboring AP. If he still connects to the AP regardless of the delay, then the AP may boot other people who are already connected in order to associate with the new connection.

Load balancing by smart classroom also limits the number of devices allowed to connect to your AP. But any new connections will be just rejected when the AP is overloaded.

Load balancing by traffic level limits the number of connections to the AP based on maximum bandwidth available. If you are uncertain as to the exact number of wireless connections you will have then choose this option. By setting a maximum bandwidth cap, you allow any number of devices to connect as long as their total bandwidth usage does not exceed the configured bandwidth cap associated with this setting. Once the cap is hit, any new connections are rejected or delayed provided that there are other APs in range.

Imagine a coffee shop in a crowded business district that offers free wireless connectivity to its customers. The coffee shop owner can’t possibly know how many connections his AP will have at any given moment. As such, he decides to put a limit on the bandwidth that is available to his customers but not on the actual number of connections he allows. This means anyone can connect to his wireless network as long as the AP has the bandwidth to spare. If too many people connect and the AP hits its bandwidth cap then all new connections must basically wait for their turn or get shunted to the nearest identical AP.