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Community Member

same AP, same network, one SSID is doing much faster than another one

Hello Guys

I encountered a really strange thing.  I have two SSIDs, let's say SSID1 on Vlan 10 and SSID2 on Vlan 20, both are setup for FlexConnect local switching in my new office.  And both SSIDs are using the only one internet link (40M).  I sat at my desk, not moving, connect to SSID1, I got 802.11n 114M, internet speed test got over 36M, then I changed to SSID2, I got also 802.11n but only 56Mm, and internet speed test only got 7-8M!!!!

So, using same internet connection, same core switch, connecting on same AP, got same .11n connection, how could one SSID did much better than another?

checked raido interface on the AP, switch ports, VLANs interface on the core switch, didn't see any error packets or other issues.  APs and the internet link are connected on the one core switch, so no different path for routing.

checked wlan settings on the WLC(5508), apart from securtity setup is different, SSID1 is using WAP2 with psk, SSID2 is using WAP2+.1x, nothing else is different.

and that happened on all my 5 new 2602i and 3 old cisco lightweight APs.


How can that happened?


Can some ones please point me the direction?


Thanks a lot.


Cisco Employee

Hi,Please do check if you


Please do check if you have enabled WMM under the SSID2. As it's mandatory to enable WMM policy to enable 802.11n data rates.



Salma Sulthana

Community Member

where can I find the WMM

where can I find the WMM setting on WLC 5508, ver 7.4.121?

Community Member

found it, in the QoS tab, and

found it, in the QoS tab, and yes both SSIDs have it allowed.

VIP Purple

I hope you configured WPA2

I hope you configured WPA2 with  AES in both scenarios (no WPA &  TKIP enable). Also WMM enable for both SSID. Those are the two primary criteria to get 802.11n data rates for a client.

I would check in both cases whether client is connected in same data rate (see the Current Rate). You can check it using "show client detail <MAC-Address>" output. Here is a sample output for a client connected to a PSK SSID.

(5508-1) >show client detail 04:f7:e4:ea:5b:66


WMM Support...................................... Enabled


Current Rate..................................... m7


Policy Type...................................... WPA2
Authentication Key Management.................... PSK
Encryption Cipher................................ CCMP (AES)




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Community Member

1, cannot change the security

1, cannot change the security settings, that is a requirement.

2, when I connected to the two SSIDs I did get different rate, as I mentioned in the case, SSID1, the fast one I got 114M something, and SSID2 I got only 56M.  But why, there are on the same AP, I was sitting steady, and just disconnected one SSID then connected to another one.

Cisco Employee

Hi, Thanks for your



Thanks for your confirmation, if you are unable to change the security policy for SSID2 kindly check with the following test.


Create an a test SSID3 with the same interface of SSID2 and use WPA2 with AES and WMM enable.

This will help us isolate the issue if it's with the network or if it's with the authentication. As I understand there will be little latency with 802.1x authentication.


Salma Sulthana

Community Member

Hello therethanks for the

Hello there

thanks for the advise, it's my suspect now as well.

But still don't understand, should the authentication only happens once while client first connects SSID2, after that security method should not matter any more, shouldn't it?

Cisco Employee

Hi, yes, you are right that



yes, you are right that the authentication happens only once when the client is associated to the WLAN. However, the type of authentication used will be counted or taken into consideration when 802.11n rates are enabled.

As there are some of the limitations to use 802.11n data rates to use either open authentication or WPA2 with AES encryption and a channel bonding to 40 Mhz under 802.11a radio.




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