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Posts: 20,598
Registered: ‎03-29-2007

[TUTORIAL] [ArubaOS 6.3 and Above] [802.11ac] - Enable VHT even if you are running 20mhz channels

[ Edited ]

It is well known that 802.11ac produces high data rates, and most people assume that you can only take advantage of higher rates when you are running 40 or 80mhz channels.  Some people cannot run 40 or 80 mhz channels due to their high density requirements.   Enabling Very High Throughput (VHT) on your 802.11a radio profile even when running 20mhz channels will also increase performance for 802.11ac clients that are connecting to those same 20mhz channels:

vht.png

Here is the output of two devices connecting to an access point running 20mhz channels with VHT turned off (802.11n or HT is turned on):  One is 3 spatial stream 802.11ac MacBook Pro and the other is a single spatial stream 802.11ac smartphone:

vht-before-2.png

 

Note the  TX and RX rates of those two devices when VHT is turned off:

 

vht-before-1.png

 

When VHT is enabled, there is no change in channel width, but we recognize clients that can take advantage of 802.11ac when VHT is enabled and we put VHT in the phy type column:

vht-after-1.png

 

Both of those clients also receive a bump in their TX and RX rate when VHT is enabled:

vht-after-2.png

 

The access point is only running 20 mhz channels, but just enabling VHT in the 802.11a radio profile will give a boost to 802.11ac capable clients connecting to an 802.11ac access point with VHT enabled.

 

(host) #show ap ht-rates bssid 00:1a:1e:1e:5a:10
 
AP "AL12" Radio 0 BSSID 00:1a:1e:1e:5a:10 High-throughput Rates (Mbps)
----------------------------------------------------------------------
MCS  Streams  20 MHz  40 MHz  40 MHz SGI
---  -------  ------  ------  ----------
  0   1          6.5    13.5    15.0
  1   1         13.0    27.0    30.0
  2   1         19.5    40.5    45.0
  3   1         26.0    54.0    60.0
  4   1         39.0    81.0    90.0
  5   1         52.0   108.0   120.0
  6   1         58.5   121.5   135.0
  7   1         65.0   135.0   150.0
  8   2         13.0    27.0    30.0
  9   2         26.0    54.0    60.0
 10   2         39.0    81.0    90.0
 11   2         52.0   108.0   120.0
 12   2         78.0   162.0   180.0
 13   2        104.0   216.0   240.0
 14   2        117.0   243.0   270.0
 15   2        130.0   270.0   300.0

 

(host) # show ap vht-rates bssid 6c:f3:7f:e6:52:f1
AP "Corp-ac" Radio 0 BSSID 6c:f3:7f:e7:51:f0 Very-high-throughput Rates (Mbps)
------------------------------------------------------------------------------
MCS  Streams  20 MHz  20 MHz SGI  40 MHz  40 MHz SGI  80 MHz   80 MHz SGI
---  -------  ------  ----------  ------  ----------  ------   ----------
0    1          6.5     7.2        13.5    15.0        29.3     32.5
1    1         13.0    14.4        27.0    30.0        58.5     65.0
2    1         19.5    21.7        40.5    45.0        87.8     97.5
3    1         26.0    28.9        54.0    60.0       117.0    130.0
4    1         39.0    43.3        81.0    90.0       175.5    195.0
5    1         52.0    57.8       108.0   120.0       234.0    260.0
6    1         58.5    65.0       121.5   135.0       263.3    292.5
7    1         65.0    72.2       135.0   150.0       292.5    325.0
8    1         78.0    86.7       162.0   180.0       351.0    390.0
9    1         --      --         180.0   200.0       390.0    433.3
0    2         13.0    14.4        27.0    30.0        58.5     65.0
1    2         26.0    28.9        54.0    60.0       117.0    130.0
2    2         39.0    43.3        81.0    90.0       175.5    195.0
3    2         52.0    57.8       108.0   120.0       234.0    260.0
4    2         78.0    86.7       162.0   180.0       351.0    390.0
5    2        104.0   115.6       216.0   240.0       468.0    520.0
6    2        117.0   130.0       243.0   270.0       526.5    585.0
7    2        130.0   144.4       270.0   300.0       585.0    650.0
8    2        156.0   173.3       324.0   360.0       702.0    780.0
9    2         --      --         360.0   400.0       780.0    866.7
0    3         19.5    21.7        40.5    45.0        87.8     97.5
1    3         39.0    43.3        81.0    90.0       175.5    195.0
2    3         58.5    65.0       121.5   135.0       263.3    292.5
3    3         78.0    86.7       162.0   180.0       351.0    390.0
4    3        117.0   130.0       243.0   270.0       526.5    585.0
5    3        156.0   173.3       324.0   360.0       702.0    780.0
6    3        175.5   195.0       364.5   405.0        --       --
7    3        195.0   216.7       405.0   450.0       877.5    975.0
8    3        234.0   260.0       486.0   540.0       1053.0   1170.0
9    3        260.0   288.9       540.0   600.0       1170.0   1300.0

 

 



Colin Joseph
Aruba Customer Engineering

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MVP
Posts: 1,110
Registered: ‎10-11-2011

Re: [TUTORIAL] [ArubaOS 6.3 and Above] [802.11ac] - Enable VHT even if you are running 20mhz channel

Thanks for the great tutorial!  I assume the bump comes from improved modulation?

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Super Contributor I
Posts: 300
Registered: ‎12-01-2010

Re: [TUTORIAL] [ArubaOS 6.3 and Above] [802.11ac] - Enable VHT even if you are running 20mhz channel

Great Stuffs. Thanks Joseph.

Normal Guy
Guru Elite
Posts: 20,598
Registered: ‎03-29-2007

Re: [TUTORIAL] [ArubaOS 6.3 and Above] [802.11ac] - Enable VHT even if you are running 20mhz channel


thecompnerd wrote:

Thanks for the great tutorial!  I assume the bump comes from improved modulation?


Yes, it does.



Colin Joseph
Aruba Customer Engineering

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MVP
Posts: 729
Registered: ‎03-25-2009

Re: [TUTORIAL] [ArubaOS 6.3 and Above] [802.11ac] - Enable VHT even if you are running 20mhz channel

Thanks, but might wanna leave the screenshots a tiny bit bigger next time please.

Koen (ACMX #351 | ACDX #547 | ACCP)

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Guru Elite
Posts: 20,598
Registered: ‎03-29-2007

Re: [TUTORIAL] [ArubaOS 6.3 and Above] [802.11ac] - Enable VHT even if you are running 20mhz channel

What screenshots?



Colin Joseph
Aruba Customer Engineering

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MVP
Posts: 729
Registered: ‎03-25-2009

Re: [TUTORIAL] [ArubaOS 6.3 and Above] [802.11ac] - Enable VHT even if you are running 20mhz channel

the last 3 command outputs.

Koen (ACMX #351 | ACDX #547 | ACCP)

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Guru Elite
Posts: 20,598
Registered: ‎03-29-2007

Re: [TUTORIAL] [ArubaOS 6.3 and Above] [802.11ac] - Enable VHT even if you are running 20mhz channel

Can you see what they say?



Colin Joseph
Aruba Customer Engineering

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MVP
Posts: 729
Registered: ‎03-25-2009

Re: [TUTORIAL] [ArubaOS 6.3 and Above] [802.11ac] - Enable VHT even if you are running 20mhz channel

Barely. I did zoom in to stop myself from squinting to see it properly.

May just be me, I do not have the best eyesight in the world.

Koen (ACMX #351 | ACDX #547 | ACCP)

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Guru Elite
Posts: 20,598
Registered: ‎03-29-2007

Re: [TUTORIAL] [ArubaOS 6.3 and Above] [802.11ac] - Enable VHT even if you are running 20mhz channel

[ Edited ]

Just kidding :)

 

Unfortunately the command that shows the association rate has alot of columns and it is very very small as a result.  I could just post the result and hope that everyone just believes me...  Hopefully everyone understands what they need to do to replicate this and they don't have to squint at my data..



Colin Joseph
Aruba Customer Engineering

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