Client load-balancing

[mlieber]

Hi all,

a short question.

Is there a feature in Cisco WLC like load-balancing based on bandwidth utilization?

What I mean is, one AP (channel6) has a channel utilization of 40%, the neighbor AP (channel 11) has a channel utilization of 10%.

So I would like push new clients automatically to the AP in channel 11.

many thanks

Martin

[Surendra BG]

Hi,

The feature callled Aggressive Load Balancing on the WLC does this Job.. the below link will help you out!!

http://www.cisco.com/en/US/products/ps6366/products_tech_note09186a00809c2fc3.shtml

Lemme know if this answered ur question!!

Regards

Surendra

[dmantill]

Surendra however it is not per chanel utilization. Aggressive load balancing is per ammount of users..

[George Stefanick]

It doesnt work worth a crap anyway ... Most clients don't adhere to code 17 so what's the point ...

Aggressive load-balancing works at the association phase. If enabled       and the conditions to load-balance are met, when a wireless client attempts to       associate to a LAP, association response frames are sent to the client with an       802.11 response packet that includes status code 17. This code indicates that       the AP is too busy to accept any more associations.

It is the responsibility of the client to honor, process or discard       that association response frame with reason code 17. Some clients ignore it,       even though it is part of the 802.11 specification. The standard dictates that       the client driver must look for another AP to connect to since it receives a       "busy" message from the first AP it tries. Many clients do not do this and send       the association request again. The client in question is allowed on to the       wireless network upon subsequent attempts to associate.

[dmantill]

+5 for that...  Usually aggressive load balancing  just cause alot of problems LOL

[George Stefanick]

I did extensive testing and white paper on LB and its not worth a darn ... Almost all the clients I tested ... ignored code 17 ..

[dmantill]

By any chance you have that lab report? I am interesting on  see that

[George Stefanick]

I think getting to the root problem of your channel utilization is important. Do you have 1 meg

frames as mandatory ? This can lead to high utilization ...

If your deign is solid and you still have high utilization i might suggest powering down your access point. Perhaps even shaping the coverage with a direction antenna. Its a way of using RF to enhance your clients roaming. Make sense?

[mlieber]

Hi,

many thanks to all.

I don't have a problem with this issue, one of our customers has asked me if it is possible to configure something like that.

And I have read in the config guide in RRM - DCA this:

Load—Load is taken into account when changing the channel structure to minimize the impact on
clients currently in the wireless LAN. This metric keeps track of every access point’s transmitted
and received packet counts to determine how busy the access points are. New clients avoid an
overloaded access point and associate to a new access point.

But I think that this isn't the same and I didn't found any further information about this configuration parameter like client threshold.

In the same page there is also a description about utilization but I think it is only for monitoring.

Or are there any CLI hidden commands available?

[weterry · Accepted solution]

There is no feature on the AP/WLC that load-balances if the AP's CU is too high. "Load-Balancing" refers to quantity of clients and not the CU itself. As George pointed out, most clients don't honor the rejection (which is why we have to build in a mechanism to only reject a client X # of times so we can eventualy let them associate.

Now regarding what I think you are asking. The expectation is that the Client will have its own logic to choose not to roam to an AP/Channel if CU is too high. The QBSS Parameter in our beacon specifically advertises Client Load and Channel Utilization for a client to see. So a client has every right to decide not to use that AP if it thinks the count or utilization is too high.

I assume the line about "new clients" avoid loaded AP might be referencing intelligent clients that listen to our advertised QBSS value, but I honeslty have never seen such a client myself.

[mlieber]

thanks for the answer

[Andrew Vlasek]

So what happens if you limit the number of clients per AP? If the clients still see that AP as the best signal stregnth AP will they continue to try to join that AP and get rejections for ever? My scenario is two APs to handle load in a conference room and I am seeing 27 people join one AP and the other AP gets no clients or 1 client most of the time. Signal stregnth settings are set to automatic and seem to always be defaulting to full power even though the APs are 10-15 feet apart. If I set them both to say 15 clients max will this resolve this issue or will I just have clients reporting they can't connect?

[Scott Fella]

What is the power level for both AP's currently and for each radio?

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[Andrew Vlasek]

Both power levels are auto setting to full power "1" channels are different.

[Scott Fella]

Well I don't really see why clients would prefer one ap over the other in the same room. I have many installs with two or more in a room and as long as the power is not set too low like 7-8, clients have balanced themselves out.

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