Cheat Sheets

Here are my published cheat-sheets that you are welcome to download & use:



Popular posts from this blog

The 5GHz “Problem” For Wi-Fi Networks: DFS

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Wi-Fi networking provides us with 2 bands for the operation of wireless LAN networks: the 2.4Ghz band and the 5GHz band. The 2.4GHz band has a reputation of being something of a “sewer” of a band, due to its limited number of usable channels, the number of Wi-Fi devices already using the band, and the high levels of non-Wi-Fi interference that it experiences. Many wireless LAN professionals will generally advise that you put your “important stuff” on the 5GHz band whenever possible. 5GHz has far more channels available, a corresponding lower number of devices per channel, and generally suffers much lower non-Wi-Fi interference. However, beneath the headline of “2.4Ghz = bad, 5Ghz = good”, there lurks a shadowy figure that can be troublesome if you’re not aware of its potential impact: DFS. Background Wi-Fi networks operate in areas of RF spectrum that require no licence to operate. This is in contrast to many other areas of the radio spectrum that generally require some form of (p...
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Adjacent Channel Interference

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I was inspired to try a bit of experimentation following Keith Parsons' recent WiFi stress testing sessions, where he conducted testing on a number of vendor APs to observe at what point they collapsed in to a heap  due to traffic throughput. I can't carry out anything as grand or detailed as Keith (I don't have his knowledege, brains or resources!), but I thought it might be fun to test some de-facto rules around the use of the 2.4GHz band for WiFi. In summary, due to the bandwidth requirements of WiFi equipment, it recommended that the spacing of at least 22MHz is allowed between the channels being used in the 2.4GHz band. This is required for the bandwidth requirements of the older DSSS modulation scheme. The newer OFDM modulation technique requires only 20MHz of space, but for reasons of backward compatibility, the 22MHz rule persists. The band itself is sliced up in to 11, 13 or 14 channels depending where you are in the world. Each channel is 5MHz in width, as ...
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What Are Sticky Clients?

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One term you'll often hear banded about when talking with Wi-Fi professionals is "sticky clients". I thought it might be worth spending a few moments exploring what is meant by "sticky clients", why they are generally considered to be a bad thing in Wi-Fi networks and some approaches to mitigate them. Background Many folks dealing with Wi-Fi networks often talk about the "sticky" characteristics of wireless clients when discussing client roaming within a W-iFi network. In an ideal world, we'd like to have access points providing ubiquitous coverage across our desired area providing high-quality, consistent client coverage where-ever we go. In this wonderful land of rainbows and unicorns, our clients would gracefully roam from AP to AP, detecting and associating with their closest AP throughout the coverage area to ensure their best connection speed at all times. Unfortunately, the real world doesn’t quite reflect this roaming-client...
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