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Radio Policy 802.11g only vs 802.11b/g only

thefranmanatt
Level 1
Level 1

What is the difference?  I tried 802.11g only and it still sends out beacons with the B rates listed (send at 1mbps also).

CCNP - Wireless
CWNE #136
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art-barrera
Level 1
Level 1

So let me start by apologizing for not "getting" what you're saying because I see a few different things that were all talking about.  The captures and how you names them cleared things up a bit. 

I believe we are all talking about a few things and you're looking for a specific answer.  Please let me know if this short list is where we've ended up or a wrong perception:

1) What does the WLAN Radio Policy actually do when configured from the WLAN section of the controller?

2) What does changing the data rates in the settings of the 802.11b/g radio result in?

3) What causes a station to not be able to connect based on settings on the controller.

My humble 2 cent responses:

1) WLAN Policy does not set any parameters on the radio or how it behaves.  I believe you are simpy given an option to apply WLAN (General, Security, QOS and Advanced) parameters on a particular Radio.  The Radio policy configured in a separate place will dictate how the radio behaves and talks.  I think of the WLAN Radio Policy of more asking "Where do you want me to apply these parameters?"

2) Both your captures titled G Only and BG beacon showed that you had 1Mbps data rate set to mandatory.  I'm assuming that those captures were named based on how you had the WLAN Radio Policy set and not how you had the data rates set on the radio itself.  This will never change until it's changed on the 802.11b/g radio parameters no matter what you have the WLAN Pollicy set to.  The radio will beacon showing every data rate available and pass along mandatory rates at the same time.  This will be done for every WLAN that has a Radio Policy for that radio.

3) We can clearly see that when you set the 802.11b/g radio to have a mandatory data rate of 1Mbps and 18Mbps, the phone would not connect since it could not support the rate.

Again, I apologize if I'm missing the boat but I'm trying to learn here too If I'm competely wrong, please let me know as I welcome the feedback.

//art

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38 Replies 38

Stephen Rodriguez
Cisco Employee
Cisco Employee

802.11g only lets a 'g' client on.

As for the beacons, take a look at Wireless > 802.11/b/g/n > network, and see what rates you have enabled.

HTH,
Steve

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Please remember to rate useful posts, and mark questions as answered

HTH,
Steve

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Please remember to rate useful posts, and mark questions as answered

How does it know to block the B clients?  I'd think that if it was G only it wouldn't have the B rates supported at all.  What I'd like to know is what exactly changes when you change that setting.

CCNP - Wireless
CWNE #136

Like mentioned, if you disable 'B' rates, B clients will not join. Doing this, just disables beacons on those rates. Beacons are allowed on the lowest mandatory data rate. Makes sense?

Sent from Cisco Technical Support iPhone App

-Scott
*** Please rate helpful posts ***

Maybe I wasn't clear.  I understand how to disable the data rates in order to block off B clients.  That isn't my question. 

I want to know what exactly happens when selecting G only on the WLAN.  From what I have seen It still uses the B rates so clearly it isn't disabling the B rates in order to make it G only.  Does it just ignore B clients trying to join, does it tell the B client it can't join?

Why does it matter?  because the data rates are a global change (at least pre 7.2).  So if I have 10 WLANs that need to be G only and one that needs to be B only (B only WLAN would be the only WLAN on the AP, no shared WLANs).  One would think you could set the WLANs and not have to take B rates'  airtime wasting hit.

To mix it up 7.4 now has an 802.11N only RF profile.  Does this mean greenfield or what?

You  can configure an access point to work in an 802.11n-only mode for an  access point group base. In this mode, the access point broadcasts  support for 802.11n speeds. Only 802.11n clients are allowed to  associate with the access point.

Configure the 802.11n-only mode by entering this command:

config rf-profile 11n-client-only enable rf-profile-name

For more information, see the Configuring RF Profiles chapter of the Cisco Wireless LAN Controller WLAN Configuration Guide, Release 7.4.

CCNP - Wireless
CWNE #136

The b/g policy allows both .11b and .11g clients to associate.

The g only policy rules out any .11b clients from joining.

I’m not sure why we have this policy setting on the network when you can accomplish the same thing by disabling all the .11b rates and keeping the .11g rates enabled. Changing the policy causes all the APs to reboot and rejoin. Changing just the rates does not require a reboot or rejoin of the AP.

A clarification: There is no such thing as a “g only” client. All .11g clients must also work on .11b only APs or using only .11b rates. So a .11b device is a subset of a .11g device.

Any rates you set as mandatory on the network must be supported by all clients you expect to join the network.

Scenario:1 I’ve one data rate set as mandatory on b and g rate. -> Both b only and g clients can connect.

Scenario:2 have one data rate set as mandatory on b rates only -> all clients can join, .11b and .11g.

Scenario:3 have one data rate set mandatory on g rates only. -> only .11g clients can join.

Supported rates are rates that the client and AP can actually send data packets between each other (directed traffic), depending on how good the link is currently.

Guys, I understand how G and B work and disabling the data rates.  That is not my question.

That still doesn't explain how the controller stops the B clients from joining.  For example when you set the max users per AP in 7.2 code the AP will tell the client it is full and won't let it join, the client moves on to the next AP. I figured someone would know the answer off of the top of their head.  I guess I need to dig out an old B client and sniff it.  I think I have a B device around here somewhere.

CCNP - Wireless
CWNE #136

IIRC it's in the beacon/probes.  The AP doesn't say that it can do anything other than OFDM

HTH,
Steve

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Please remember to rate useful posts, and mark questions as answered

HTH,
Steve

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Please remember to rate useful posts, and mark questions as answered

What does this have to do with B rates ?

If max user or load balance is enabled one of two things happen. Either the AP ignores the probe request from the client OR the ap responds to the client with a REASON CODE 17 ..

thefranmanatt wrote:

Guys, I understand how G and B work and disabling the data rates.  That is not my question.

That still doesn't explain how the controller stops the B clients from joining.  For example when you set the max users per AP in 7.2 code the AP will tell the client it is full and won't let it join, the client moves on to the next AP. I figured someone would know the answer off of the top of their head.  I guess I need to dig out an old B client and sniff it.  I think I have a B device around here somewhere.

__________________________________________________________________________________________
"Satisfaction does not come from knowing the solution, it comes from knowing why." - Rosalind Franklin
__________________________________________________________________________________________
‎"I'm in a serious relationship with my Wi-Fi. You could say we have a connection."

"Satisfaction does not come from knowing the solution, it comes from knowing why." - Rosalind Franklin
___________________________________________________________

It doesn't directly but that is the type of answer I am looking for.  People are reviewing data rates and saying to turn that off to disable B, etc...  I just want to know what really happens when you change that option. 

You are right about the reason code 17 for max users.   

CCNP - Wireless
CWNE #136

Change what option .. youre not clear in your question..

__________________________________________________________________________________________
"Satisfaction does not come from knowing the solution, it comes from knowing why." - Rosalind Franklin
__________________________________________________________________________________________
‎"I'm in a serious relationship with my Wi-Fi. You could say we have a connection."

"Satisfaction does not come from knowing the solution, it comes from knowing why." - Rosalind Franklin
___________________________________________________________

from my first post

Radio Policy 802.11g only vs 802.11b/g only

What is the difference?  I tried 802.11g only and it still sends out beacons with the B rates listed (send at 1mbps also).

I am not sure what isn't clear about that question.

CCNP - Wireless
CWNE #136

Oh I c .. Did you capture the beacon .. It will show what is supported .. Does it show dsss phy rates when it's g only

What code are you on ..

Sent from Cisco Technical Support iPhone App

"Satisfaction does not come from knowing the solution, it comes from knowing why." - Rosalind Franklin
___________________________________________________________

Radio policy with 802.11g only will allow only 802.11g clients, however, if your data rates are set to 1mbps mandatory, then that is where all you beacons will be sent. Your wireless adapter is using all available data rates so its your client that is sending them at 1mbps in which you are allowing 1mbps. Makes sense?

Sent from Cisco Technical Support iPad App

-Scott
*** Please rate helpful posts ***

Man this forum is hard to follow, new post end up in the middle of the thread..  it is like try to have a discussion on twitter.

I understand if you set it to G it doesn't allow B clients.  How does it tell the B client it isn't allowed?  Something has to change in how the controller works. I want to know what it is that has changed.

CCNP - Wireless
CWNE #136
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