Adjusting Data Rate and Threshold on Cisco CBW Access Points

[magic]

Hi:

I have Cisco CBW240AC access points. In the controller software, Under Advanced RF Parameters, I don't understand the difference between adjusting the 5.0 Ghz Threshold (6,9,12 Mbps, etc.) vs. adjusting the 5.0 GHz Data Rates with the same selections, 6,9,12 Mbps, etc.

I'm not sure if the above tweaking will help me but this is what i'm trying to get out of it. Using only 1 SSID, I want to stay on 5.0 GHz as much as possible, disable the 2.4 GHz band in the trouble free areas (if possible) but I have some areas where I cannot get good 5.0 Ghz overlap so I want the AP to kick off the client from the 5.0 GHz band and push the device to the 2.4 GHz band, and use 2.4 band to either stay in that weaker area or use it until transitioning back to a good 5.0 GHz area.

If anyone can explain the difference and how it can help me out and/or how they're typically used would be helpful. I attached a screen shot of the config window.



Thanks!!

 

[magic]

No one?

If I'm not mistaken, my question is not necessarily for Cisco CBW users. I believe all the business grade access points have the capability to make similar adjustments, maybe not in terms of "data rates" but by RSSI values.



Thanks!

 

[ColinTaylor]

Maybe this will help:

https://www.cisco.com/c/en/us/td/docs/wireless/access_point/csbap/CBW_Admin/Admin/en_US/b_Cisco_AP_Admin_Guide.pdf

Page 101 "Optimized Roaming"

 

[magic]

@ColinTaylor - I appreciate the help but it didn't help clear my confusion still. I have that guide but since you were so kind to pass me the link, I did read that section again. In fact, the guide mentions "SSID" thresholds, but the software doesn't even call it that. The software calls it data rates. So I had google search for a conversion from SSID values to data rates to get a better understanding what the SSID values mean in terms of the software. Even then, what i found wasn't a Cisco site so i'm not sure on the accuracy of it.

Anyway, the way i'm reading the 2 software setting is, it's the same setting but reworded so that's confusing me.

I was hoping to get feed back from @jasonreg , @Tech9, @Trip who are familiar with Cisco. But I think most other AP systems have similar settings, but maybe not called the same thing.

Thanks!!

 

[Tech9]

Sorry, I use WAP571 APs in single point setup configuration. The UI looks completely different and I don't use any similar adjustments.

 

[magic]

@Tech9 - no prob, i appreciate you responding. I can understand the UI being different but I was hoping the same adjustments were in there.

 

[Trip]

@magic - Answers to your questions:

Threshold is the level of negotiated throughput between AP and client, below which the AP will send a BSS disassociation request (hopefully causing the client to roam). This setting allows you to "craft" client roaming behavior (at least minimally), as you can set the throughput value at which the APs will try to hand-off clients. A nice feature, presuming you have enough co-adjacent signal from a neighboring AP at any given location where the hand-off would be happening (that's on you as the wifi engineer to make sure that's the case).

Data Rate is the minimum level of client throughput offered by any/all APs. Excluding certain low data rates (used almost exclusively by legacy devices, such as those with 802.11b radios) helps to improve efficiency of the entire WLAN. It can also help with eliminating "sticky" clients from hanging onto AP connections for too long, causing excessive retransmits, resulting in hogged airtime and lowered performance of the entire WLAN. Be careful here, though, as getting rid of too many rates may not allow certain clients to connect at all. Long story short: I'd probably leave the slider at "9", maybe "12". For more info on this subject, here's a decent article: Why You Should Disable Lower Legacy Data Rates.

Hope that helps!

 

[magic]

@Trip - Thank you so much. That gave me a better understanding. I was able to tweak my roaming a hair bit better. That was a good article too.

Overall I like this CBW, but I'm disappointed I couldn't get this question answered on the Cisco Community forum. Anyway, I'm glad I went with the 240AC, I think I would have really struggled with the 140AC's for my place. Not sure if you saw my other post, but I lucked out with the the deal I got on the 3-pack so that set me up good.

Thanks again.

 

[Trip]

@magic - Very welcome. Glad you went with the 240's, and nice catch on the deal.

And yeah, Cisco's forum-based support can be hit or miss, especially for their small business (now just "Business") line, which is an afterthought compared to the enterprise stuff. In all fairness, though, they're still pretty good when factoring in everything (support lifetime, security patching, etc).