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Dual radio 5GHZ channel plan [HCD high client density design]

RavKam
Level 1
Level 1

Hello,

Currently I've created a design which for HDD office and I observe high utilization  (70-80%) on APs with breaking Teams sessions as a (annoying!) symptom
The APs (9800WLC+CW9166i) have peaks with 45 - 50 users per AP, 95% of users are 5GHz, but still the number of 6GHz-capable users is too low to turn on this option.

So my ""clever"" plan is to use second 5GHz radio to gain a better split of users per radio on the same AP and make the utilization lower without buyin' new APs. I know - I have to use DART cable to connect a secondary omni antenna...
I'm in Europe with the following channels available: 36, 40, 44, 48, 52, 56, 60, 64, 100, 104, 108, 112, 116, 120, 124, 128, 132, 136, 140.
The question is how to plan channels usage per radio as I couldn't find any clear answer.
Should I go with pairs on AP like
36+40, 44+48, 52+56  
or 
36+140, 40+136, 44+132
or it doesn't matter at all?
I've 12 APs per floor (5 floors on square plan) so I can use 9 double-channel APs per floor and repeat only 3 APs  with the same channels per floor with low Tx power so I don't worry about CCI.
Also I can setup different Tx power per radio to have maco-micro cells environment

Any risks, better solutions ?
THA

14 Replies 14

@RavKam 

  For me a better solution is add more APs, or, add appropriate number of APs.  But, if you go with the solution of dual radio, you should not worry about channel plan or power control, the WLC is there for that reason. 

Have you considered converting the 6 GHz radio role to 5 GHz?

The third radio on the CW9166 has the flexibility to be configured as either a 6 GHz or 5 GHz radio. This is referred to as a dual-band XOR radio.

jaganchowdam_0-1729188023359.png

Commands to convert radio role:

ap name <ap name> dot11 dual-band slot 2 shutdown
ap name <ap name> dot11 dual-band slot 2 radio role manual client-serving
ap name <ap name> dot11 dual-band slot 2 band 5ghz
ap name <ap name> no dot11 dual-band slot 2 shutdown

Commands to Revert radio role to 6GHz:

ap name <ap name> dot11 dual-band slot 2 shutdown
ap name <ap name> dot11 dual-band slot 2 radio role auto
ap name <ap name> no dot11 dual-band shutdown

By converting the 6 GHz radio to a 5 GHz role, you can effectively double the number of 5 GHz radios. If you decide to make this change, I recommend keeping the channel width at 20 MHz to minimize co-channel interference (CCI). Additionally, it’s best to allow the controller's Radio Resource Management (RRM) to handle channel and power planning.

This approach enables you to maximize the use of your existing access points without needing to invest in additional antennas.

Jagan Chowdam

/**Pls rate useful responses**/

 

eglinsky2012
Spotlight
Spotlight

When the 9166i is in dual 5 GHz mode, Slot 1 can only be set to channels 36-64 and Slot 2 can only be set to channels 100 and above. At least, that's how it is in the U.S on 17.9/17.12 code. That 36-64 range only allows (4) 40 MHz channels on Slot 1, which makes things difficult.

Beware, however, that you may experience slow throughput on Slot 2 when it's operating in 5 GHz mode. More information on my experience with that here: https://community.cisco.com/t5/wireless/9166-xor-radio-slow-in-5-ghz-mode/m-p/5210622#M276676

I have a lecture hall with (7) 9166i APs, and the per-radio channel range limitation made 20 MHz channels necessary instead. If I had fewer APs, I wouldn't feel bad about using 40 MHz channels as long as there would be enough channels available for neighboring APs.

Due to the Slot 2 slowness, I'm currently using only Slot 1 on 5 GHz on all the APs, with (5) of the radios using 80 MHz channels and (2) that tend to have less clients using 40 MHz. I can get by with this because the spectrum is clean and the room is very isolated from neighboring APs. We've had good results with this setup, but I think the dual 5 GHz mode would be better yet if Slot 2 would perform adequately.

Thanks for your reply.
So please make my thoughts clear: in dual 5G mode I don't need to use any external antenna ?
My original thought was to use external antenna (omni or directional) via DART cable so  I would (???) have two full-blown operational 5G radios, not to mention to cover two different physical areas...


@RavKam wrote:

So please make my thoughts clear: in dual 5G mode I don't need to use any external antenna ?
My original thought was to use external antenna (omni or directional) via DART cable so  I would (???) have two full-blown operational 5G radios, not to mention to cover two different physical areas...


It depends. In your original post, you stated the APs in use are 9166i, so my previous comments were focused on that model. You can have two full-blown operational 5G radios by switching the 6 GHz radio to 5 GHz (if Slot 2 can perform adequately per my previous comments). Unlike the 2800/3800 series, the 9166 XOR radio can be powered up as high as desired, so you can have the radios macro-macro, macro-micro, or micro-micro.

The 6E indoor APs don't have an external antenna option. If you want a directional coverage pattern, you'll need to purchase the 9166d model instead. Otherwise, the 9166i can provide the dual omni 5 GHz radios.

More info in the 9166 datasheet: https://www.cisco.com/c/en/us/products/collateral/wireless/catalyst-9166-series-access-points/catalyst-9166-series-access-points-ds.html

Leo Laohoo
Hall of Fame
Hall of Fame

@RavKam wrote:
APs with breaking Teams sessions as a (annoying!) symptom

Are the Teams sessions breaking on laptops (but work fine with tablets and smartphones)?

Well, I'm focused only on laptops as a main end-user tool.
High channel utilization (65%-85%) is a major symptom + over 35-45 users /AP
after a session with Microsoft tech-support they emphasized signal level even better than -65dBm.
So enabling secondary 5G radio should better distribute users per AP (+RxSOP tuning ) + macro-macro or macro-micro (+Tx power tuning) cells scenarios also might be used.

Please answer the question:  Are the Teams sessions breaking on laptops (but work fine with tablets and smartphones)?

I don't see your point...
I did not check it because laptops are devices which I'm interested in.
AFAIK laptops have better antennas than phones/tablets, in most cases better wireless cards and bigger batteries so less chance for "Tx asymmetry" in connectivity device <--> AP


@RavKam wrote:
I don't see your point...

I don't ask stupid question. 

I ask because I want to know if the issue is mostly with laptops or smartphones/tablets.  Laptops have wireless NIC that requires wireless NIC drivers to be update or else they will hit two known bugs when they are connected to Catalyst 9k APs.  Smartphones and tablets do not have this issue. 

If the issue is mostly affecting only the laptops, then provide the information about their wireless NIC and what are their respective wireless NIC drivers.

And the question about "is this affecting only laptops or also affects smartphones/tablets" is one of the most basic wireless troubleshooting question everyone asks.  

Let's start from the beginning
Please don't put in my mouth words which were not spoken...
In my vocabulary "I don't see your point..." doesn't mean stupid

The clients use laptops for normal activity -not their phones/tablets.
I can try to test phone/tablets -but again I must focus on laptops.
The drivers are updated regularly to the Microsoft-recommended version. If you can point the exact version of  driver -please do,
I can provide NIC types/providers...

"And the question about "is this affecting only laptops or also affects smartphones/tablets" is one of the most basic wireless troubleshooting question everyone asks.  " -well... maybe...
But also I hear: "I don't care if my phone works... I do my job using laptop, so please solve the issue for my laptop..."
Phones and tablets are also usually computers and they also need drivers - the other thing is the quality of these drivers...
Using a laptop is a constant struggle to use the wifi card manufacturer's driver or the microsoft driver, using the manufacturer's driver guarantees the use of the full capabilities of the card - but not the stability of windows. Forced windows drivers may be more stable but they do not use the full capabilities of the card...
And so on and so forth... it is no so monolithic like Apple or even Android 

Anyway -thank you for advise I can try 

The "Cisco Catalyst 9800-CL Wireless Controller version is 17.9.4a" -any better version for CW9166?
However ... I have over 2000 mixed types of APs here -so I cannot be ""flexible"" here...

I hope that this explains a bit ...


@RavKam wrote:
The clients use laptops for normal activity -not their phones/tablets.
I can try to test phone/tablets -but again I must focus on laptops.
|The drivers are updated regularly to the Microsoft-recommended version. If you can point the exact version of  driver -please do,
I can provide NIC types/providers...

For Realtek RTL88xx, the wireless NIC driver should be, at a minimum, 6001.10.352.0 (and later).  Refer to CSCwf03870

For Intel-based AX2xx, the wireless NIC drivers should be 22.200.2.1 (and later) or 22.220.0.0 (and later).  Refer to CSCwe50033

Thanks!

FYI the Microsoft baseline Intel driver version is now 23.60.0.10.  The latest Intel version is now 23.80.1
https://www.intel.com/content/www/us/en/download/19351/intel-wireless-wi-fi-drivers-for-windows-10-and-windows-11.html

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