Access Point Upgrade to AP3702i

[Marvin Krym]

I swapped the access points in an area from AP1252 to AP3702i and both are running the same image version, 7.6.130. Without changing any of the RRM settings or AP positions, the transmit power went up by about 10 dB in the 5 GHz band when measured using tools like AirMagnet. The power levels set by RRM also went up.   I would appreciate any help to understand why the power levels went up.  I expected them to be about the same.

Thanks.

[Leo Laohoo]

I swapped the access points in an area from AP1252 to AP3702i and both are running the same image version, 7.6.130. 

Personally, I wouldn't take any comparative reading after two or three days.  The new APs need to "sniff" out the air before the WLC starts re-adjusting the radio transmitter strengths.  

If you're replacing like-for-like and you get a different reading like that, then yes, OK. 

[Rasika Nayanajith]

3702 support 802.11ac data rates which mean 256 QAM modulation which require higher power tx in order to clients to receive these modulated signals clearly. If you look at the data sheets max Tx power of 3702 now is 200mW (23dBm) where as in previsous AP model it is 100mW (20dBm)

http://www.cisco.com/c/en/us/products/collateral/wireless/3700-series-access-point/data_sheet_c78-729421.html

If you simply replace 1:1  802.11a/b/g/n AP with 802.11ac like 3700, your cell size will be larger. So you have to disable low data rates & control cell size. Here is a very very good presentation to go through to understand the importance of control the cell size.

http://www.cwnp.com/uploads/jerome-henry_understanding-cell-size.pdf

HTH

Rasika

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[Marvin Krym]

In my case, I am using 11a with 11n and 11ac disabled.  In both cases, the beacon data rate is 6 Mbps.  When taking power measurments, I am effectively measuring the beacon power which I believe is transmitted with one spatial stream.  I assumed that measurements would account for differences in antenna patterns. The measurements were made after several days to allow the system to stabilize.  Only under all of these limited conditions, I thought the two APs would behave similarly.  Thank-you for the excellent presentation from the recent cnwp conference.

[Rasika Nayanajith]

What was the power level of 3700 5GHz operate & comparative 1252 ?

Good idea to disable 6Mbps & 9 Mpbs ( & make 12Mbps mandatory) in order control how far these management frames can go.

HTH

Rasika

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[Abhishek Abhishek]

Upgrade Cisco IOS through the CLI

This section describes how to upgrade Cisco IOS on an access point through the CLI.

1. Log into the access point through a Telnet session.

2. You can download a new image file and choose to replace the current image or keep the current image.

   Note: Refer to Cisco Software Downloads FAQ for information on how to download firmware from Cisco.com Downloads.

   Note: The latter option is helpful when one of the Cisco IOS files are corrupted. You can work with the access point from the other image in the flash.

3. If you choose to overwrite the existing file, issue the archive download-sw /overwrite /reload tftp://location/image-name command. The /overwrite option overwrites the software image in flash with the downloaded image. The /reload option reloads the system after you download the image unless the configuration is changed and not saved. For //location, specify the IP address of the TFTP server. For image name, specify the Cisco IOS filename that you plan to use to upgrade the access point. In this example, the command is archive download-sw /overwrite /reload tftp://10.77.244.194/c1240-k9w7-tar.124-10b.JA3.tar. As mentioned earlier, do not change the name of the Cisco IOS file. Leave it as the default. You find these logs during the successful file transfer:

   examining image...
   Loading c1240-k9w7-tar.124-10b.JA3.tar from 10.77.244.196 (via BVI1): !
   extracting info (275 bytes)
   Image info:
       Version Suffix: k9w7-.124-10b.JA3
       Image Name: c1240-k9w7-mx.124-10b.JA3
       Version Directory: c1240-k9w7-mx.124-10b.JA3
       Ios Image Size: 4813312
       Total Image Size: 5560832
       Image Feature: UNKNOWN
       Image Family: C1240
       Wireless Switch Management Version: 1.0
   Extracting files...
   c1240-k9w7-mx.124-10b.JA3/ (directory) 0 (bytes)
   c1240-k9w7-mx.124-10b.JA3/html/ (directory) 0 (bytes)
   c1240-k9w7-mx.124-10b.JA3/html/level/ (directory) 0 (bytes)
   -----------------Lines omitted ---------------------------
   ----------------------------------------------------------
   Deleting target version: flash:/c1240-k9w7-mx.124-10b.JA3...done.
   New software image installed in flash:/c1240-k9w7-mx.124-10b.JA3.
   Configuring system to use new image...done.
   Requested system reload in progress...

4. If you choose to keep the existing file, issue the archive download-sw /leave-old-sw /reload tftp://location/image-name command. If there is not enough space to install the new image and keep the current running image, the download process stops, and an error message is displayed.

5. The AP downloads the Cisco IOS file specified from the DHCP server and reloads with the new software.