2.4/5Ghz load-balancing - Utilize on BOTH

[n.poongsawad]

Hi,

In my class room, a lot of new Dell notebook (university purchased) all of those are the same model. Those came with 2.4&5Ghz WLAN NIC.

So, my WLC-based AP in that room which is Cisco 1x1042 & 1x1252 running in light-weight.

This make huge congest on 5 Ghz. All of my 41 NB go for 5Hgz. And Zero client on 2.4Ghz radio, 2.4Ghz is not utilized at all.

I have read a lot of those related discussion. But I even can not find one that need to utilized BOTH of band. Most of those discussion talking to band-select which is "this feature only goes in one direction from the 2.4 GHz range to the 5 GHz not visa-versa."

My constrint is We can not touch the NB. Because this is university, much many diverse user loging in.

Any suggestion would be very appriciated.

Thnak you,

Nipat.p

[Leo Laohoo]

Firstly, you need a WLC to utilize BandSelect.

Next, regarding the utilization of your 5.0 Ghz against 2.4 Ghz:

1.  Have you checked the configuration of the WAPs?  Maybe the NB goes for the 5.0 Ghz because the configuration is correct.  Maybe the 2.4 Ghz radio is disabled?

2.  Have you checked the configuration of the NB?  Maybe the netbook has been configured to go with 5.0 Ghz. 

3.  What is the wireless NIC model?

4.  What's wrong with 5.0 Ghz?  Why do you want the NB to go to 2.4 Ghz?

[n.poongsawad]

Leolaohoo,

I did test with native WLC configure & also native PC configure. I ran a windows script on all 41 PC to do downloading repeatly with wget.exe. The first PC download with 40Mbps then I go though the second the third to the 41th PC. Then all 41 PC do download at the same time. Result make me surprise, speed bacame around 2Mbps. (huge drop)

After that I investigated on my WCS that show us 17 PC using 5Ghz of the first AP, 24 PC using 5Ghz of another AP. none of PC join 2.4Ghz on both AP. Should it be by all NATIVE cnfg?

From yr Q,

1. I try to make some tuning, enable band-select & client load-balance (per WLAN) then kill connection and reconnect. Some of PC comes to 2.4G but just 9 from 41. So, 2.4 is not disaled. But my turned on band-select show put most of PC to 5Ghz isnt it?

2. PC cnfg to turn on both 2.4/5 by default.

3. Let me tell you soon

4. 5Ghz is not wrong but it just oversubscription while 2.4 is underutilized. WCS warned 5Ghz interface became "Interface violation"

It there any perform cnfg that make 2.4&5 loadbalnce roughly equa?

Please do me suggestion.

Nipat.p

[Leo Laohoo]

4. 5Ghz is not wrong but it just oversubscription while 2.4 is underutilized. WCS warned 5Ghz interface became "Interface violation"

I don't know how you deployed your WAP but I find it hard to believe that the 5.0 Ghz is "interfering" while your 2.4 Ghz is NOT?  If this is correct, then your 2.4 Ghz would most likely to be disabled.

Please check and ensure that the Dynamic Channel Assignment (DCA) is enabled.

[n.poongsawad]

Hi leolaohoo,

Thx for your reply. But my issue is not "interfering" I said my 5ghz radio was oversubscription while no one associated for 2.4Ghz. Anyway, my whole WLC box was native configure, I have never turned 2.4Ghz of through DCA myself, so 2.4Ghz still on. WCS also shown out 2.4Ghz is running.

I found Aruba has this feature that I need "spectrum load-balance"

http://www.arubanetworks.com/pdf/technology/DG_Roaming.pdf

Spectrum load-balance tried to eveNly load balnceing client by radios and AP. Cisco has one?

Once in my mind I need to completly disable Band-Select out of this SSID. But what happen if all PC is dual band that natively prefer 5Ghz then they all probe/reauest to join 5Ghz before try on 2.4Ghz. All PC goes 5Ghz then congest!!!

Plz suggestion some tuning.

Nipat.p

[Leo Laohoo]

PC is dual band that natively prefer 5Ghz then they all probe/reauest to join 5Ghz before try on 2.4Ghz.

Nothing you can do about it.  It is the client (and not the WAPs) that decides which band and which WAP to associate to.

[Saravanan Lakshmanan]

check the client default behavior based on its configuration, some client type usually prefer 2.4 while other 5ghz.

#Try aggressive load balancing on the WLAN and see if it helps, however it is per WLAN to load balance between AP and again not per radio. it require connecting client to be ccx certified.

#If clients using same physical location with spot coverage then hardcode some clients to use 2.4ghz and other to 5ghz or

create two similar ssid map some to 2.4 and others to 5ghz.

#Configuring Maximum Number of Clients per AP Radio per WLAN, limit the no.s per radio and force the client to spread between radios.  config wlan max-radio-clients max_radio_clients wlan_id.

[SOcchiogrosso]

Leolaohoo is correct, Cisco might Band Select will be the way to go. If I remember correctly Band Select ignores the first few frames on 2.4 GHz range so the 5GHz frequency looks more readily available. You might have to turn-off Band Select or tweak the configuration.

I find it a little odd the 2.4 GHz is not used at all, you might want to make the 2.4 GHz range is not experiencing any kind of interference from other neighboring devices (Other AP, microwave, cordless phones, etc) before switching your clients over to. Usually the 2.4 GHz fills up first.

http://ccie-or-null.net/2010/12/20/bandselectrssi/

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