Sniff Wi-Fi

Auto-channel selection protocols have been an increasingly common source of controversy for enterprise Wi-Fi administrators.  Aruba's ARM, Cisco's RRM, Ruckus's ChannelFly and Aerohive's ACSP all allow a centralize management entity -- either controller or software -- to automatically set the channels of access points (APs).  These protocols can be big time savers during the surveying and implementation stages, but also can cause big headaches once the Wi-Fi is up and running.   The argument over whether to use auto-channel selection protocols may be coming to an end, however.  802.11k is becoming more widely supported in Wi-Fi devices, and when smartphones, tablets and other devices support 802.11k, the decision is a no-brainer: auto-channel should be avoided because it makes roaming worse. To understand the impact that 802.11k (radio resource measurement) has on Wi-Fi devices, one first must understand a fundamental fact about Wi-Fi: devices control connections.

Everybody likes high Wi-Fi speeds.  Because high Wi-Fi speeds mean that the channel is being used more efficiently ( often false ).  An efficient channel means that there's more available throughput ( only in sterile test environments ) and more available throughput means that more users can be supported concurrently ( completely wrong ). Unfortuantely, high Wi-Fi speeds sometimes  ( all the time )  come at a cost.  To get higher Wi-Fi speeds, wider channels must be used ( which makes the Wi-Fi suck ).  Using wider channels means that fewer channels will be available ( plus it ups minimum RSSI requirements, which just about guarantees a bad design ).  It is therefore essential that wireless professionals analyze the environment and carefully choose whether to use 40 MHz or 80 MHz wide channels ( or they could stop wasting everyone's time and just stick to 20 MHz channels ). But this blog post isn't about choosing the correct channel bandwidth ( although it should be, b