One of the most commonly cited best practices among Wi-Fi professionals is to the limit the number of SSIDs you have configured on your WLAN in order to reduce the amount of overhead on the network and to maintain high performance. Call Of Duty 2 Exe File. But there is not a lot of public data out there to really drive home this point when explaining it to another engineer, management, or a customer. Simply telling someone that they shouldn't create more than 'X' number of SSIDs isn't very convincing. Therefore, I've created a visual tool to help you explain WHY too many SSIDs is a bad thing: The Wi-Fi SSID Overhead Calculator (Click Image to Download). This tool calculates the percentage of airtime used by 802.11 beacon frames based on the following variables: • Beacon Data Rate - beacon frames are sent at the lowest Basic / Mandatory data rate configured on the WLAN.

Beacons must be sent at a 'legacy' data rate, meaning only 802.11a/b/g rates. Select the beacon data rate from the drop-down menu within the tool. • • Beacon Frame Size - beacon frames can vary in size based on the version of the 802.11 standard implemented (802.11a/b/g/n/ac) and features enabled on the WLAN (such as 802.1X authentication, CCX, 802.11r fast roaming, and 802.11u Hostpost 2.0). List Three Hardware Components Commonly Installed On A Desktop Computer. I recommend using a wireless sniffer to capture a beacon frame from your WLAN for use within the tool. Enter a beacon frame size that represents the total size of the MAC header and data payload. Rapidshare Book Acting more.

• • Beacon Interval - beacon frames are sent at a default interval of 102.4ms, but this may be modified in most enterprise WLAN products. Note that beacons are always sent at a multiple of the Time Units (TUs), where one TU equals 2^10 Kilomicroseconds (or 1.024 milliseconds). Therefore, 100 TUs equals 102.4ms. Enter the time interval between beacons, in milliseconds. The calculation includes the inter-frame spacing (using WMM), physical layer preamble and header, MAC layer header, and data payload. It calculates the amount of time required for modulation of the bits over the air, but does not account for collisions or retransmissions. Technically, you wouldn't reach 100% airtime utilization on a Wi-Fi network because medium contention due to collisions and retransmission backoff result in a maximum airtime utilization of around 80-90%.