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MODULE 11

LOAD BALANCING

LEVELLING THE LOAD ON WIRELESS

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At the end of this module, you will be able to:

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Objectives

• Identify Load Balancing Strategies• Describe Smart Band Control• Identify where to enable Load Balancing• Discuss Load Balancing Statistics

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Load Balancing

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Overview

• Load Balancing allows the WiNG5 network to distribute the network load in order to provide better service to existing and future clients (that may connect or roam soon)

• Supported strategies are– Loads per AP in a neighbourhood– Loads per channel per band in a

neighbourhood– Loads between bands (2.4/5) in a

neighbourhood• Load

– The number of users on an AP and the number of users on a particular frequency band/channel and throughput generated across the WLAN (ESSID) according to configured parameters.

– Configured per WLAN and per AP• Special UI to monitor the stats of load

balancing machine

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Strategies

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Strategies

• Loads per AP in a neighbourhood:– Each AP monitors and attempts to equalize its total load with

those of the APs in its neighbourhood• Here on picture: 2 clients per AP

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Strategies• Loads per channel per band in a neighbourhood:

– Each AP attempts to evenly distribute its load across the channels of each of the bands in its neighbourhood.

• Example– 2 Clients on Ch11 and 1 Client on Ch6– 3 Clients evenly distributed across Ch 36,44,48

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Strategies• Loads between bands in a neighbourhood:

– Each AP attempts to load the 2.4 GHz band and the 5 GHz band in a ratio that is configurable.

• Example– Clients Loads per Frequency Band 3:1– 6 Clients on 2.4 Ghz / 3 Clients on 5 Ghz

• (2:1 < 3:1)

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SMART Band Control

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SMART Band Control

• Smart Band Control – Detects dual radio clients – Distributes clients in each radio band based on a configurable ratio or percentage– Introduced in WiNG 5.1

2:1 Ratio

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Motorola Public Document Classification, October 2011

Dual Band Clients

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How dual band clients are handled

• An MU associates to an AP, which in turn learns the MU’s band capabilities– The AP then sends out a WNMP roam-notification to all other AP’s,

advertising the MU’s band capabilities– Other network AP’s update a special MU band-capability table for

subsequent roams– New AP can then influence MU’s selection of band if necessary

WNMP2.4GHz

5GHz

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What if client won’t change bands?

• 2.4GHz is heavily loaded; a new client shows up– AP ignores probe requests, attempting to push client to 5GHz– Client persists probing at 2.4GHz

• AP may interpret this as client being temporarily unable to connect at 5GHz (perhaps due to radar avoidance).

– Once a pre-configured probe-request threshold is exceeded, AP allows client to connect at 2.4GHz

2.4GHz

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Enable Load Balancing

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Per WLAN Configuration• Enable at WLAN; set time for client band discovery:

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Per AP Configuration• Enable at the Profile or Device level:

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Viewing Statistics

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Viewing Statistics

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Motorola Public Document Classification, October 2011MOTOROLA, MOTO, MOTOROLA SOLUTIONS and the Stylized M Logo are trademarks or registered trademarks of Motorola Trademark Holdings, LLC and are used under license. All other trademarks are the property of their respective owners. © 2011 Motorola Solutions, Inc. All rights reserved.

You should now be able to:

• Identify Load Balancing Strategies• Describe Smart Band Control• Identify where to enable Load Balancing• Discuss Load Balancing Statistics

MODULE SUMMARY