Dec 30 2013

How Tennessee’s Harpeth Hall School Maximizes Network Performance

A well-considered network optimization strategy begins with these practices.

Nashville, Tenn.’s Harpeth Hall School started a one-to-one notebook computer program more than 15 years ago, when networks were much simpler. Every year since, we have added more devices — and more network traffic.

Before I asked the chief financial officer for more funding to buy additional devices, I wanted to ensure that we were making the most of the technology we already had in place.

Our ultimate goal was to create a lightning-fast network that would effectively support both new and existing hardware. The following optimization best practices transformed our network’s overall performance and can do the same for other schools and districts.

Develop a Strategy

Every technology project, no matter its size or scope, must begin with a detailed plan. Harpeth Hall leaders developed a five-year technology plan to identify the tasks on which we needed to work — and a timetable for completing that work.

We considered all aspects of our IT program, but we focused heavily on our network usage growth and what that might do to our local area network and wide area network infrastructure. Internet bandwidth, wireless throughput and switching capabilities were among the topics addressed in the plan. Every year, we discuss as a team any adjustments that need to be made to that plan.

Trying to predict what technology we’ll be using in five years can be a challenge — particularly because, in the IT world, change is constant. With that in mind, we developed a strategy for handling basic, overarching issues rather than assembling a detailed shopping list. (Examples might include “upgrade wireless infrastructure to current-generation technologies” or “provide 10-gigabyte fiber links to every building or closet.”)

Don’t try to guess which model of equipment you’ll purchase a few years from now; instead, think about what might create a future bottleneck and how to address it.

Embrace Virtual LANs

Every device connected to a wired or wireless network is going to cause some network chatter, in the form of Address Resolution Protocol requests sent to the broadcast address. This isn’t necessarily a problem when a school doesn’t have a large amount of devices connecting to its network.

But for Harpeth Hall, the challenge is magnified because of the diversity and volume of devices that contribute to our network traffic, including servers, wireless projectors, notebooks, desktops, tablets, mobile and desktop phones, security cameras and even door access card readers.

Many simple network devices have a hard time dealing with all of this network chatter, causing them to work intermittently. To circumvent this problem and improve communication, break device broadcast domains into small groups using virtual local area networks. Smaller groups lead to less chatter. As a rule, if 250 or more devices are accessing a network, it’s time to turn to VLANs.

VLANs also allow IT staff to separate networks logically by building or department with different subnets and to isolate traffic for security purposes. Harpeth Hall makes VLAN assignments based on the building in which users are located, the department to which they belong and even grade level.

Trust in QoS

Most network switches work on a best-effort model for delivering data. This model gives all data an equal chance of being delivered. Some types of network traffic are more important, however; quality of service (QoS) allows IT to assign a higher network priority to certain critical applications.

At Harpeth Hall, we figured out which network traffic was most important to us and then assigned QoS to this traffic via our switch and firewall. Phone systems and media- or file-sharing applications are typically the most popular candidates for QoS. Doing this ensures that phone reliability won’t be affected by what other network users are doing on YouTube or Facebook, for example.

Boost Internet Bandwidth with Web Caching

One thing that became obvious on my campus in recent years was the need for more Internet access. Every year, Internet utilization would increase so much that we’d have to invest in a faster connection. Occasionally, I’d hear teachers complain that the Internet was slow on a particular day. After talking with the teacher more, I’d typically discover that she had had all of her students visit a certain website when other teachers were simultaneously doing the same in their classrooms.

To alleviate this problem, I installed a web caching server. Now, instead of 20 students downloading the same thing 20 times, one student downloads it from the Internet and the other 19 download it from the school’s local web cache server. About 40 percent of all Internet traffic that passes through campus now uses the web cache server.

We currently have a 400-megabyte connection, resulting in bandwidth savings of about 120MB and annual Internet bill savings of roughly $6,000.

Capitalize (Selectively) on New Technology

It isn’t necessary to upgrade equipment every time something new comes out, but there are times when doing so can make a measurable difference. Wireless is a great example of this. Every major wireless advancement has brought with it improved speed and performance. But cost is a factor.

Besides paying a premium for the newest technology, IT departments may have to upgrade other components of their network to support those additions. For example, 802.11ac wireless needs Power over Ethernet switches with 1GB connections and 10GB links back to the core to be efficient.

Harpeth Hall also recently upgraded most of its servers to Microsoft Windows Server 2012 to support Hyper-V and clustering, which also resulted in faster network and server traffic and a 50 to 80 percent increase in transfer speeds for large files.

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