Low speed in 802.11n

Unanswered Question
Mar 23rd, 2011

Hello,

I am having problems with 802.11n (the WLC is a NME-AIR-WLC6-K9, running verson 7.0.98.0, and the APs are /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabela normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} AIR-CAP3502-I-T-K9). We are very close to APs, but the clients connect at 72 Mbps.

I don´t know what I am doing wrong, because I enabled the 11n Mode, all MCS Data Rates, 40 MHz for 802.11a and Guard Interval is any.

Some outputs that can help:

(Cisco Controller) >show 802.11a

802.11a Network.................................. Enabled
11nSupport....................................... Enabled
      802.11a Low Band........................... Enabled
      802.11a Mid Band........................... Enabled
      802.11a High Band.......................... Enabled
802.11a Operational Rates
    802.11a 6M Rate.............................. Disabled
    802.11a 9M Rate.............................. Disabled
    802.11a 12M Rate............................. Disabled
    802.11a 18M Rate............................. Mandatory
    802.11a 24M Rate............................. Supported
    802.11a 36M Rate............................. Supported
    802.11a 48M Rate............................. Supported
    802.11a 54M Rate............................. Supported
802.11n MCS Settings:
    MCS 0........................................ Supported
    MCS 1........................................ Supported
    MCS 2........................................ Supported
    MCS 3........................................ Supported
    MCS 4........................................ Supported
    MCS 5........................................ Supported
    MCS 6........................................ Supported
    MCS 7........................................ Supported
    MCS 8........................................ Supported
    MCS 9........................................ Supported
    MCS 10....................................... Supported
    MCS 11....................................... Supported
    MCS 12....................................... Supported
    MCS 13....................................... Supported
    MCS 14....................................... Supported
    MCS 15....................................... Supported
802.11n Status:
    A-MPDU Tx:
        Priority 0............................... Enabled
        Priority 1............................... Disabled
        Priority 2............................... Disabled
        Priority 3............................... Disabled
        Priority 4............................... Enabled
        Priority 5............................... Enabled
        Priority 6............................... Disabled
        Priority 7............................... Disabled
    Guard Interval .............................. Any
Beacon Interval.................................. 100
CF Pollable mandatory............................ Disabled
CF Poll Request mandatory........................ Disabled
CFP Period....................................... 4
CFP Maximum Duration............................. 60
Default Channel.................................. 56
Default Tx Power Level........................... 0
DTPC  Status..................................... Enabled
Fragmentation Threshold.......................... 2346
TI Threshold..................................... -50
Legacy Tx Beamforming setting.................... Enabled
Traffic Stream Metrics Status.................... Enabled
Expedited BW Request Status...................... Disabled
World Mode....................................... Enabled
EDCA profile type................................ default-wmm
Voice MAC optimization status.................... Disabled
Call Admission Control (CAC) configuration
Voice AC:
   Voice AC - Admission control (ACM)............ Disabled
   Voice max RF bandwidth........................ 75
   Voice reserved roaming bandwidth.............. 6
   Voice load-based CAC mode..................... Disabled
   Voice tspec inactivity timeout................ Disabled
   Voice max limit on number of call............. 0
CAC SIP-Voice configuration
   SIP Codec Type ............................... CODEC_TYPE_G711
   SIP call bandwidth ........................... 64
   SIP call bandwith sample-size ................ 20
   Voice Stream-Size............................. 84000
   Voice Max-Streams............................. 2
Video AC:
   Video AC - Admission control (ACM)............ Disabled
   Video max RF bandwidth........................ Infinite
   Video reserved roaming bandwidth.............. 0
   Best-effort AC - Admission control (ACM)...... Disabled
   Background AC - Admission control (ACM)....... Disabled


Configurantion of the WLAN:

WLAN Identifier.................................. 1
Profile Name..................................... WlanCorpData
Network Name (SSID)..............................
WlanCorpData
Status........................................... Enabled
MAC Filtering.................................... Disabled
Broadcast SSID................................... Enabled
AAA Policy Override.............................. Disabled
Network Admission Control

  NAC-State.............................
DHCP Address Assignment Required................. Disabled
Quality of Service............................... Silver (best effort)
Scan Defer Priority.............................. 4,5,6
Scan Defer Time.................................. 100 milliseconds
WMM.............................................. Allowed
Media Stream Multicast-direct.................... Disabled
CCX - AironetIe
Local EAP Authentication......................... Disabled
Security

   802.11 Authentication:........................ Open System
   Static WEP Keys............................... Disabled
   802.1X........................................ Disabled
   Wi-Fi Protected Access (WPA/WPA2)............. Enabled
      WPA (SSN IE)............................... Disabled
   Conditional Web Redirect...................... Disabled
   Splash-Page Web Redirect...................... Disabled
   Auto Anchor................................... Disabled
   H-REAP Local Switching........................ Disabled
   H-REAP Learn IP Address....................... Enabled
   Client MFP.................................... Optional
   Tkip MIC Countermeasure Hold-down Timer....... 60
Call Snooping.................................... Disabled
Roamed Call Re-Anchor Policy..................... Disabled
Band Select...................................... Disabled
Load Balancing................................... Disabled

Mobility Anchor List
WLAN ID     IP Address            Status
-------     ---------------       ------

Please help me guys...

Regards,

Marco Bartulihe

I have this problem too.
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Nicolas Darchis Wed, 03/23/2011 - 14:11

Is it the client claiming to associate at 72Mbps ? or is that the throughput you measured ?

Association rate claimed by client should reach 300Mbps but real throughput should be around 150Mbps.

What is the client adapter model you are using ?

Some clients cannot actually do that speed as they can only do one spatial stream (so they get half the speed that other clients can achieve).

Regards,

Nicolas

marco_bartulihe Thu, 03/24/2011 - 06:01

The notebooks are Dell Latitude E5410, and they can get 150 Mbps because the user, in his home, get this speed with a D-Link.


So I think that there is something wrong in the configuration...

Regards,

Marco Bartulihe

Nicolas Darchis Thu, 03/24/2011 - 06:15

You're not answering the question.

Do they see "associated to SSID x at 72Mbps" ? Or do they measure 72 Mbps with a tool ?

Their laptop brand also doesn't say which wireless adapter they have as Dell is loading various adapters on that model.

Explanation why I'm asking this.

It could be that they associate at 300Mbps to the Cisco wireless but measure only 72 Mbps of throughput. It can then be any problem involving network,WLC, etc ...

If they associate really only at 72Mbps, that means they use a low MCS rate. We can then analyze why then don't assocaite at MCS rate 15 (300Mbps).

Nicolas

marco_bartulihe Fri, 03/25/2011 - 11:50

Hi Nicolas,

I think that you guide me through the answer...

The wireless card of the notebooks are DW1501 Wireless-N (http://support.dell.com/support/edocs/network/p70008/en/vista_7/sp1501hm.htm), and the technical specs says:

Data rate (Mbps)
IEEE 802.11b: 1, 2, 5.5, 11
IEEE 802.11g: 1, 2, 5.5, 6, 9, 11, 12, 18, 24, 36, 48, 54
IEEE 802.11n, 20 MHz bandwidth: Max 72

The user see "associated to SSID x at 72Mbps", as should be, because of they wireless card.

Another important point is the confusion that the user did. He actually don't connect at 150 Mbps in his home with this notebook.

Thank you very much for the tip!

Regards,

Marco Bartulihe

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Posted March 23, 2011 at 12:39 PM
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