Q: I want to set up two different wireless networks in the same room. Each one has a different Service Set Identifier (SSID). I am using two Symbol 4121 access points for one network, set to channels 1 and 11. Two Linksys access points for the second network are set at channels 4 and 8. Again, both networks use a different SSID but both use the same WEP key. Is this a workable situation? Is there a better way?
- Gil B.
The wizards gaze into their crystal ball and respond:
Leonid Kalika, Strix Systems
This is definitely not the most effective way to set up different wireless networks in the same physical location. First, the fact that both sets of access points are using the same WEP key is somewhat irrelevant, aside from the fact that should someone get the key, they will have access into both networks. Secondly, WEP is not a particularly effective means of securing a network. Unless you are running voice clients and don’t have any option, the first thing I would suggest is you move to a more advanced security scheme.
You have made a good effort at keeping the access points from interfering with each other by selecting the channels you did. However, there is a better way for you to create multiple wireless networks in the same physical location. Many access points can create virtual wireless networks using the same equipment. For example, you can install only two access points, and configure them to broadcast multiple SSIDs, or even multiple Basic SSIDs (BSSID), so it will appear that there are multiple wireless networks installed, when in fact there is only one (read more here). Then the access points can do the work for you and auto-select channels to minimise interference.
Typically, vendors that offer these types of solutions will let you set up different security schemes by SSID and virtual network, so one virtual network might be using WEP for encryption, while the second virtual network might use WPA.
Finally, for vendors that offer the more advanced multiple BSSID option, you can even create separate access control lists per BSSID since they will each appear to have their own MAC address.
Jason Luther, Airwave
This doesn't sound like an optimal solution. Within the unlicensed spectrum used by your Wi-Fi devices, there are only three channels that do not overlap with other channels: 1, 6, and 11. In your example, your access points on channels 1, 4, 8, and 11 are going to interfere with one another and affect performance. You're better off using channels 1, 6, and 11.
With four access points in one room, you will still have to set two of the access points to the same channel. Ironically, in this situation, you're probably better off having two adjacent access points on the same channel rather than putting them on channels that overlap only slightly.
By sharing the same channel, the access points will actually share the bandwidth better - using channels that overlap only slightly causes interference instead of sharing. You'll probably want to use your wireless network management solution to reduce the RF transmission power of these access points below the maximum threshold.
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