Wireless Access

Hi:

I'm looking to remove the low data rates 1Mbps and 2Mbps, but I'm confused about Basic Rates and Transmit Rates.

Right now these rates are checked:

802.11g Basic Rates: 1,2

802.11g Transmit Rates: All

 

If I want to remove 1 and 2 Mbps, I assume that I need to uncheck those rates for both Basic and Transmit?

Also, is there any reason not to have all rates 5 and above checked for both Basic and Transmit?

 

Thanks,

Tony

 

 

 

 

Your two lowest data rates should be your basic rates.


Thanks,
Tim

Hi Tim:

Thanks for the info.

Does that apply to a as well?

I currently have 6,12, and 24 selected as 802.11a Basic Rates, and all 802.11a Transmit rates selected.

I believe this was the default, as I haven't poked around in these settings before.

 

Thanks,

Tony

Correct.

Do you still support 11b devices on your network? If not, you should consider knocking off even more rates.


Thanks,
Tim

Hi Tim:

Sorry, I'm not sure I understand. When you said "Correct" did you mean that my 'a' config was correct?

Also, no b supported here. What data rates do you recommend for a college campus?

 

Thanks,

Tony

Sorry. Correct as in the same logic is used for the 11a radio.

 

It's best to test the data rates in a building for a week or so to see if any issues are being reported.

 

This is a great tool to help you determine data rates for your environment:

https://ase.arubanetworks.com/solutions/id/75

 

Thanks for the info.

One more question: To turn of b mode, do I simply disable 1,2,5.5, and 11Mbps?

Or is there something else I need to do?

Or can I leave those low rates for g to use in DSSS mode? (not that I necessarily want to, but just curious)

 (actually, now that I think about it, g in DSSS mode is probably the exact same thing as b, isn't it?)

 

Thanks,

Tony

Your logic is correct. But in reality there is no 11 (1,2), 11b (5.5, 11), 11g (6-54) anymore. Think of it is that specific amendment introduced that rate. The rates still exist but are all the amendments are wrapped up in the latest 802.11 standard. So all are with the standard.

 

Your are correct that the rates are based on the modulation schemes. I'd agree to remove 1,2,5.5,11, and while you are at it 6 and 9. 

I checked with Aruba TAC and they said to leave the Basic Rates set at 1 and 2, even if the lowest transmit rate was set to 12.

Tim's suggestion (two lowest transmit rates are used as the basic rates) seems to make more sense.

Thoughts?

 

I completely disagree with that unless you are supporting devices that
require those rates (which are very few these days).

Right. If you're not supporting those rates, why advertise them?

Makes sense.

Thanks, Tim.

 

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@Tony1234 wrote:

Right. If you're not supporting those rates, why advertise them?

Makes sense.

Thanks, Tim.

 

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it's not just advertising them that is the problem, it is also that the beacons and perhaps other frames (depending on mcast-rate-opt setting) will still be going out at 1Mbps, creating a perception of a  larger coverage area than is actually now in place as a result of removing 1,2,5 from the lower end of the tx rates. Also starts to get us to weird places where some clients will just happily use those basic rates as tx rates, some may not.  finally, not raising the g-basic rates means we dont get to take any advantage of reduced co-channel interference via increased beacon rate (which just tracks the lowest basic rate by default)

 

At the end of the day, with few exceptions, the basic rates are a subset of the lowest tx rates, first two is good enough (if you are confident you can do 1st and 3rd etc).

 

regards

jeff

Hi Tim:

Thanks for all your help on this.

One more question:

I run one SSID across campus. To test different data rates in different buildings, I would need to create a separate ap-group, wlan virtual-ap, and wlan ssid-profile that broadcasts the same SSID as the others.

Will roaming and authentication work properly if two different ssid-profiles are broadcasting the same SSID?

Thanks,

Tony

Hi Tim:

We run one SSID across all buildings. In order to test this out in one building, I would need to setup a new ap group, wlan virtual-ap profile, and wlan ssid profile,that broadcasts the same SSID.

Will that work? Will that cause any problems with users roaming?

Thanks.