NXC5500/2500

Version 4.20Edition 2, 02/2015

Copyright © 2015 ZyXEL Communications Corporation

Application Note

Smart Classroom Load Balancing

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Smart Classroom Load BalancingFor wireless access service, the Smart Classroom requirements are far different fromcommon office applications. Inter-action, real-time multimedia content access inhigh density environments e.g. 30~50 students simultaneously access digitaleducation materials is a fundamental requirement in Smart Classroom scenario.ZyXEL’s tailor-made Smart Classroom Load Balancing feature enables fast client loadbalancing between two access points deployed in one classroom, providing a reliableand non-stop wireless access service. This application note illustrates how toconfigure Smart Classroom Load Balancing step by step.

Scenario

To ensure an instant and non-stopping wireless access, two access pointsimplementation in one smart classroom is fundamental and crucial for digitaleducation. While students access the digital materials in class, the smart classroomload balancing feature distributes wireless traffic between 2 APs to relieve loading onthe network, a fast user load balance is achieved between two access points toguarantee smooth multi-media lecturing. On the contrary, while one AP fails toserve, the other AP instantly takes over the access service and ensures a non-stopwireless access experience in smart classroom scenario.

Purpose

The AP would stop sending probe/association/auth response once the “Max. StationNumber” is reached. Also, the AP would disconnect all excessive stations once byRSSI.

Condition

Two APs need to be in the same subnet and use same SSID, security and mode (2.4/5GHz) to utilize the load balancing feature.

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Benefits

§ Fast reach of load balance

· Whenever there is a station that tries to associate, and if the AP is

overloaded, it will check a “neighbor table” to see is there is a

neighbor, if yes, then it will stop sending a probe/association/auth

response, and disconnect over-threshold-stations every 20 sec based

on the most idle/ poor RSSI status stations.

§ Stations assigned to nearest AP

§ All stations in the classroom are guaranteed a connection

· If there is no neighbor or the neighbor is aged, this AP performs as

usual to accept any new station when the AP is in overloaded.

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Topology

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Configuration

Goal: To create SSID, radio and AP group profiles for a third-grade classroom andapply the third-grade AP group profile to the two NWA5123-NI devices.

1. Create radio for 2.4 GHz band via CONFIGURATION > Object > AP Profile >

Radio.

2. Create a radio profile for the 5 GHz band via CONFIGURATION > Object > AP

Profile > Radio. The Channel Selection is set to “Manual” by default.

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3. Create a security profile for the third-grade classroom via CONFIGURATION >

Object > AP Profile > SSID > Security List.

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4. Create an SSID profile for the third-grade classroom via CONFIGURATION >

Object > AP Profile > SSID List.

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5. Create an AP group profile for the third-grade classroom via CONFIGURATION >

Wireless > AP Management > AP Group.

5.1 Choose the configured 2.4 GHz band radio and SSID profile for the third-grade.

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5.2 Choose the configured 5 GHz band radio and SSID profile for the third-grade.

6. Check the Enable Load Balancing box and set the Mode to “By Smart

Classroom”.

Max. Station Number is for each radio and Disassociate station whenoverloaded is enabled by default.

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7. Since the available AP will be assigned to the “default” AP group by default, we

need to move the available NWA5123-NI to the third-grade AP group as

members.

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Verification

1. Check the applied configured on the AP via MONITOR > Wireless > AP

Information > AP List.

2. Check the applied configured on the AP via MONITOR > Wireless > AP

Information > Radio List.

3. Check the connected stations assigned on each AP via MONITOR > Wireless > AP

Information > AP List to see the Wi-Fi load balancing distributed wireless

stations between the 2 APs.

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Load Balancing Differences

Station NumberMode

Traffic LevelMode

SmartClassroom Mode

Connection DelayAssoc/Auth/Prob

DelayAssoc/Auth/Prob

Stop sendingAssoc/Auth/Prob

Kick STA Kick STA one byone mildly by Idletimeout, RSSI

Kick STA one by onemildly by Idletimeout, RSSI

Kick excessiveSTAs instantly byRSSI

§ The disassociation is determined by the followings for Station Number mode and

Traffic Level mode.

• Idle Timeout: STAs that have been idle the longest will be disassociated

first. If no STAs are idle, the priority shifts to Signal Strength.

• Signal Strength: STAs with the weakest signal strength will be

disassociated first.