Campus wireless upgrade - project details

Summary

In the summer of 2019, ITC started a major initiative to upgrade all wireless infrastructure on campus. The upgrade progress is documented in a separate KB article.

Brief history

Dartmouth's wireless network started in the late 90s/early 2000s as a convenient overlay service. Wireless networking wasn't available everywhere, and the primary network access method was via wired connections. By 2003, over 500 access points were installed. Shortly thereafter, an effort was made to bring wireless into every building. However, wireless was still treated as an overlay.

In 2011/2012, a major effort was made to introduce wireless coverage into all buildings. Wireless had become more of a primary network access method, with smart phones and tablets unable to access networks via wired connections. The number of wireless access points grew to around 2,300. The design primarily focused on 802.11n at 2.4GHz, and in many cases wiring in existing locations was used to connect the access points. In 2014/2015, additional wireless access points were installed in undergrad housing. These 'hospitality mode' wireless access points were originally designed for hotels, and were aimed at covering the needs of two hotel or dormitory rooms. This increased the total number of access points to 3,500.

2019-2021 upgrade

In 2019, ITC started a major initiative to upgrade all wireless infrastructure on campus. Since the last major re-design in 2011, the total number of concurrently connected devices had increased from 4,000 to 25,000. The vast majority of devices were wireless only. The three usable channels at 2.4GHz are hopelessly congested; channels at 5GHz work significantly better but due to how signal propagates at different frequencies, there were not access points installed to provide sufficient coverage at 5GHz. The overall goal of this upgrade is to install an estimated 6,000 wireless access points over the course of 2 years, starting in summer of 2019. The upgrade process itself for each building consists of three steps:

Active RF survey

Contractors walk the building with access points on tripods that they can set up anywhere. They then use special equipment to measure signal strength. Combined with moving the tripods around, they're able to build a three-dimensional model of the building and determine ideal placement of wireless hardware to provide good coverage at 5GHz everywhere in the building. The software that does the modeling is able to account for different use cases, and designs for parameters such as "150 students each with one laptop and one cell phone, with capacity to do online based exams". Once the model is built, it's also possible to shift proposed access point installation locations around and observe the predicted effect on wireless coverage. This step is somewhat interruptive since the model accuracy increases with the number of measurements taken. The contractors ideally will want to take several data points in every room. Project management staff from ITC works with the occupants of each building to schedule the surveys. 

Wiring AP locations

Wireless network performance is very much tied to where equipment is installed. In the past, existing wiring was often re-used in an effort to utilize existing resources. With this upgrade, the wireless design itself drives the installation location of the equipment in order to maximize performance of the wireless network. While sometimes wiring can be re-used, we're expecting to pull new wiring to more than 90% of the 6,000 access points that are to be installed. This work can be somewhat interruptive depending on the building. Pulling wiring through drop ceilings is relatively easy and quiet, but some buildings require building new pathway (which can go as far as coring through foot thick concrete floors). This step usually takes 1-3 weeks but entirely depends on the size and function of the building (as that directly affects the number of wires that need to be pulled), as well as the general building construction. We pull two wires to each access point location; this allows for future growth where wireless requires multiple uplinks at multi-gigabit speeds, but also allows for a backup connection in case one of the wires fails. Project management staff from ITC works very closely with occupants of each building to schedule the wiring contractors and to minimize interruptions and noise.

Install and activate new wireless hardware

ITC has automated the provisioning of the new wireless hardware to the point that the wiring contractors actually connect the new access points as the very last step of their wiring work. Once all new hardware is installed, ITC will coordinate with buildings occupants to choose a day and time to cut over to the new wireless system. This creates a short outage during which the legacy wireless system is administratively disabled, and the new hardware starts providing services. At that point, the wireless upgrade itself is complete. A few days or weeks after the cutover, contractors or ITC staff will remove the legacy hardware. The removal can also introduce short interruptions as people work on ladders to remove the access points and cover over any remaining wiring paths.

Details

Article ID: 91423
Created
Wed 11/6/19 8:43 AM
Modified
Wed 12/18/19 3:37 PM

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