Channels and Maximum Power Settings for Cisco 3700

The Tx Power Level Assignment for each AP shows its current power level assignment in a numbering system that starts with 1 and ends with 8. The number 1 indicates the AP is on full power and the higher the number goes less power are transmitted.

That number (1-8) can be converted to dBm or mW to show the AP’s actual power output by using this command ‘show ap config 802.11a’. It is here where you might notice the power level of APs all on power level 1 might not be transmitting the same dBm or mW.

The reason for this is the UNII band the AP is on for example below is an extraction of the ‘show ap config 802.11a’ command for three APs. All three AP’s were configured exactly the same except for Dynamic Channel Assignment (DCA) which put them on three different UNII bands.

UNII-1

Tx Power
Num Of Supported Power Levels …………. 3
Tx Power Level 1 …………………….. 8 dBm
Tx Power Level 2 …………………….. 5 dBm
Tx Power Level 3 …………………….. 2 dBm
Tx Power Configuration ……………….. AUTOMATIC
Current Tx Power Level ……………….. 1
Tx Power Assigned By …………………. DTPC
Phy OFDM parameters
Configuration ……………………….. AUTOMATIC
Current Channel ……………………… 36
Channel Assigned By ………………….. DCA

UNII-2Ext

Tx Power
Num Of Supported Power Levels …………. 5
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 Configuration ……………….. AUTOMATIC
Current Tx Power Level ……………….. 1
Tx Power Assigned By …………………. DTPC
Phy OFDM parameters
Configuration ……………………….. AUTOMATIC
Current Channel ……………………… 100
Channel Assigned By ………………….. DCA

UNII-3

Tx Power
Num Of Supported Power Levels …………. 8
Tx Power Level 1 …………………….. 23 dBm
Tx Power Level 2 …………………….. 20 dBm
Tx Power Level 3 …………………….. 17 dBm
Tx Power Level 4 …………………….. 14 dBm
Tx Power Level 5 …………………….. 11 dBm
Tx Power Level 6 …………………….. 8 dBm
Tx Power Level 7 …………………….. 5 dBm
Tx Power Level 8 …………………….. 2 dBm
Tx Power Configuration ……………….. AUTOMATIC
Current Tx Power Level ……………….. 1
Tx Power Assigned By …………………. DTPC
Phy OFDM parameters
Configuration ……………………….. AUTOMATIC
Current Channel ……………………… 149
Channel Assigned By ………………….. DCA

All three APs indicate Power Level 1 on the Wireless LAN Controller but their actual power transmit power is:
AP1 = 8dBm
AP2 = 16dBm
AP3 = 23dBm

With this information available you might want to disable certain UNII-bands as the power output is not enough for the environment the APs are in.

Below is the path to get to the Cisco provided spreadsheet indicating what the power setting will be for your regulatory domain using certain antennas, configuration settings and certain UNII-bands.

http://www.cisco.com/c/en/us/support/wireless/aironet-3700i-access-point/model.html

Under Install and Upgrade Guides click on Detailed Channels and Maximum Power Settings for Cisco 3702e and 3702i Series Access Points.

 Have fun.

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Channels and Maximum Power Settings for Cisco 3700

2 thoughts on “Channels and Maximum Power Settings for Cisco 3700

  1. Brett Verney says:

    Hi there,

    Why are the available Tx power settings so low in the UNII-1 band? I have noticed the same thing on a client’s 3700 series APs, despite the regulatory domain (Australia) allowing for up to 17dBm on that model AP. A Tx power level of 8dBm and a 4dBi gain antenna on the 3702i model, I get an EIRP of 15.8mW.

    This doesn’t help when trying to match client / AP Tx power or trying to increase SNR.

    What am I missing?

    Like

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