Live High-Density Wi-Fi Test At School Demonstrates Large Group of Students Taking Online Exams
In this article, a team of Wi-Fi experts from Aerohive Networks sets out to do a high-density radio test on a school campus located in California’s wine country. As a result of this test, it was shown that a large number of students could simultaneously take standardized online exams in places like school gyms, auditoriums, cafeterias, assembly halls, and other wide-open spaces as described in the deployment Guide for K-12 schools. For these tests, the team used Aerohive AP230 devices and had 25 student volunteers operating 250 iPads to simulate taking an online test.
The Healdsburg Unified School District had implemented Aerohive wireless networks on two of its four campuses and was about to install them on its other two when we asked Chris Moghtaderi, District Technology Coordinator, if he would be willing to let us test the high-density radio profile settings described in our new Aerohive K-12 Education Deployment Guide. He very graciously agreed to let us use one of their campuses where an Aerohive network had not yet been installed, and the date was set for July 24, 2015.
After Chris rounded up a team of student volunteers, a team of Aerohive employees headed north through San Francisco into the California wine country for a day of high-density testing in a delightful setting.
Healdsburg is approximately 65 miles north of the mid-point on the Golden Gate Bridge, and 15 miles north of Santa Rosa. It is the gateway to the Russian River and the Alexander Valley, Napa, and Sonoma wine country. Drive a short distance in any direction and you will see lush vineyards (literally dripping with grape clusters if you visit before the harvest), classic wineries with tempting tasting rooms, resort communities, redwood groves, and dairy farms. You can drive west for 31 miles along the scenic, redwood-lined River Road, through the Russian River resort communities (home of the well-known Bohemian Grove), until you emerge at Jenner by the Sea and its lovely, scenic Pacific beaches.
The Aerohive tests at Healdsburg Junior High school took place in a cafeteria and a gymnasium. The Aerohive team arrived early and, using an electric motorized cherry picker, suspended APs from the overhead beams in the cafeteria, and at strategic locations in the gymnasium (including above the backboard behind the basketball hoop).
No fancy-schmancy mounts here; instead, Aerohive team member Joe Fraher secured devices with that old reliable, duct tape, yellow nylon rope, bungee cords, and in one case lovely blue party ribbon. (He also had a great deal of fun driving the cherry picker).
Joe wrote the location, radio channels, and the last three digits of the serial number for each AP in large black letters on blue masking tape so they could be read from the floor of the rooms, both of which had 20-foot ceilings. The team installed three APs in the gymnasium, and four in the cafeteria. To ensure that there would be only three non-overlapping 2.4 GHz channels, the team disabled one of the 2.4 GHz radios on the 4th AP in the cafeteria (the “NO” on the label shown in the photo). The Aerohive team then configured wireless networks for both locations.
The iPads arrived next, in an impressive parade of portable, wheeled charging carts. Each iPad was turned on, checked for a charge level, initialized, and arranged on tables as 25 testing stations of ten iPads each. (50 of the iPads were running IxChariot.)
While this was happening, the students began to arrive and sign in. They followed a simple set of instructions to log their test-station iPads into the Aerohive network, and soon got to work. Virtually all of the school’s iPads and a few loaner Aerohive iPads were pressed into service for testing. The students earned credits toward their community service hours (required for graduation) for their participation in the testing.
The morning test was a simple mock exam of 100 questions which could be answered in any way, as long as an answer was chosen. Students joked that this was probably the easiest exam they would ever take. The network that supported all of this was composed of four APs using default radio profiles on four 5 GHz radios and three 2.4 GHz radios. The technical team watched carefully for any issues (iPads slowing, or going offline, for example), and in general, even with the extremely heavy burden of 250 exams running simultaneously, the network proved to be resilient and responsive.
To give the students a better understanding of why we were performing these tests, and why they were an important part of the testing (and perhaps to spark a budding interest in Wi-Fi and networking), Aerohive Sr. Product Marketing team member, Metka Dragos, gave an interesting and animated talk about wireless technology.
After the morning testing was completed, we broke for lunch - big, fresh sandwiches delivered by Yuki Fraher, and provided by Big John’s Market, a specialty food and wine fixture in Healdsburg (and for much of the surrounding area). Big John’s deli sandwiches are named after local attractions, such as “The Soda Rock”, “The Russian River”, “The Alexander Valley”, and so on. The students gathered at the picnic tables outside to catch up on their texting and social media tasks, and the Aerohive crew ate in the relative cool of the building interiors.
After lunch, testing moved into the gymnasium, which was festooned with banner slogans such as “California Distinguished School, 2011”, “Team HJH, PUPS: Pride, Unity, Purpose, Success”, “The HJH Way: Behave Respectfully, Behave Responsibly, Behave Safely, Be Ready to Learn!”.
In this room, Joe had affixed the APs to the walls and above the backboard of the basketball hoop, at heights of about 15 feet.
The tables and iPad stations were set up as before, and the students began the testing process using the mock exam that they had used in the morning. During this process, the Aerohive team increased the network load by switching 90 of the iPads to stream a YouTube video of Matthew Gast (an Aerohive Wi-Fi superstar) talking about error vector magnitude. The number of streaming devices was gradually increased to 120, then 150, 180, and finally 200. The team kept careful track of the load balancing data during these increases.
As the number of streaming devices grew, the room was completely overcome by layer upon layer of Matthew’s voice from the videos, giving the entire setting a surreal atmosphere. By this time, the students were extremely entertained and thoroughly behind this new wireless network as a replacement for their current network, which they agreed is very slow, and often unreliable.
At the end of the day, the Aerohive team broke down the network, removed the APs from the ceilings (running the cherry picker out of juice, briefly) and headed for the Healdsburg Grill for supper.
The network gained a considerable level of performance improvement using the high-density settings as recommended in the Aerohive K-12 Education Deployment Guide. High density settings also improved throughput, band steering, load balancing, and CRC error and Tx/Rx retry rates.
For details about the Healdsburg test results, see Part 4 of the Aerohive K-12 Education Deployment Guide:
This guide covers deployment planning, from setting coverage and capacity goals to conducting predictive and manual site surveys. It concludes by introducing the plans for an example high school deployment using AP230, AP130, and SR2148P devices.
In this guide, a network policy with three SSIDs is described. The guide shows how the SSIDs help satisfy the coverage and capacity goals introduced in Part 1.
The configuration of the network policy started in Part 2 continues here. It explains how to configure an SR2148P device template and multiple port types to support various types of Ethernet traffic.
The high-density radio profiles to support administration of large standardized online exams in the school cafeteria and gym are described in detail. These settings were validated through testing at the Healdsburg Unified District Junior High School. A summary of the test results appears at the end of the guide.
Bonjour Gateway enables clients to discover and access services on devices in different subnets/VLANs. This guide explains how to set up Bonjour Gateway so that teachers, staff, and students can access Apple TVs and printers in a different subnet and VLAN from their own.
For details about the Healdsburg test results, see Part 4 in this series.
Read How Real-world Stress Test Of High-density Wi-FI Deployment Worked by Metka to find out the details of how this test was conducted.
All posts in this series: