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Calibrating a Wireless LAN Survey Plan

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One of the most important steps in completing a WiFi network survey using  a professional survey tool is to ensure that you have a correctly calibrated the floor plans used to conduct the survey. Without this step, your survey may be inaccurate or, at worst, worthless. In this article we look at why this is important, together with the right (and wrong) way to do it. Background When performing any type of  WiFi network survey using a tool such as Ekahau’s Site Survey or Fluke’s AirMagnet, one of the first tasks performed is the creation of a survey project. During the creation of the survey project, a number of configuration tasks must be performed. One of mandatory tasks is to import an electronic copy of the floor plan of the area to be surveyed. The floor plan is generally an image file (jpg, png, bmp etc.format) that has been created from an architect’s blueprint of each floor of a building. Professional survey tools also often allow the import of AutoCad (DWG) f

Cisco WLC: Per-client Packet Capture

Sometimes, you just want to capture the packets associated with a particular wireless client and see what the heck is going on with that client. Often, it may not be practical to do an over-the-air packet capture, as perhaps the client is at a remote location or just just don't have access to a wireless capture card. I recently had an issue trying to understand why an Android device that I was trying to 'on-board' using Cisco's ISE wouldn't access the Google Play store. I desperately wanted to capture the over-the-air frames from the client to have a look at what the client was doing. After a quick 'Google' around, I found an intriguing set of Cisco WLC CLI commands that allow a packet capture of traffic for a wireless client. This can all be done without having to change the AP mode, or reboot the AP etc. In summary, the feature allows packets to be captured for a specified wireless client that is sending/receiving traffic to/from an AP. T

Cisco Access Points: Which Power Levels Does My AP Support?

Cisco APs support a number of discrete transmit power levels which are 3dB apart. They are usually numbered levels 1 (highest) down to 7 or 6 (lowest). The numbers of levels and the transmit power values assigned vary between models and regions. The quickest way to determine the levels supported by your AP is to logon to your WLC and execute the following CLI command: show ap config 802.11b <ap-name> This will list out a whole lot of information, including a section which starts with the title: "TX Power". This contains the levels and corresponding dBm levels supported. Here is a sample: Tx Power       Num Of Supported Power Levels ............. 6       Tx Power Level 1 .......................... 16 dBm       Tx Power Level 2 .......................... 13 dBm       Tx Power Level 3 .......................... 10 dBm       Tx Power Level 4 .......................... 7 dBm       Tx Power Level 5 .......................... 4 dBm       Tx Power Level 6 .....