Adventures In Mac-book Wireless Roaming, Part 1

The Setup

I work for a company where we almost exclusively use mac-books both air and pro. Over the last year I've learned a few things about mac-books and macOS X wireless roaming limitations. It all started simply enough as our company expanded form a few hundred users to now over 4 thousand and still growing. We started to get increasing reports of wireless roaming issues.  Clients getting knocked off and even completely losing connection for minuets at a time after walking from a desk to a conference room.  Not good for a company heavily dependent on G-suite and hangouts.

First Attempts

Our sites are mixed between Cisco and Aerohive wireless. We have been transitioning to Aerohive over the last 6-8 months and the number of Cisco sites is dwindling as most of our sites move every 2 years. This transition is based on a combination of factors including ease of provisioning sites(we stand up an office on average every month and a half), technology/innovation, and price. When reports started to come in we implemented the usual roaming and high density improvements.

1. Turn down power to limit cell sizes

2. Disable low rates, 24M as basic rate and everything below disabled to limit cell sizes.

3. Enable rxsop or weak SNR probe suppression to shrink cell size

4. Enable 802.11k to speed client transition to the best AP

5. Enable 802.11r to reduce auth overhead and speed roaming

6. Enable 802.11v to warn clients they should move before being disassociated

7. Enable opportunistic key caching(on by default on Cisco)

While these actions did greatly improve roaming for our mobile devices and windows laptops things only got worse for the Macs.

Hitting The Books

After getting more reports that the mac problem didn't improve with the rest of the clients we figured it was time to do some research.  It turns out the internet is awash with reports of macs having terrible roaming on enterprise wireless systems some with vague recommendations on what to do but without reasons why they might help, but not a lot of references on what causes the issue or any documentation.  You will even find deployment and best practice guides from Cisco on how to configure your wireless best for apple devices but only covering iOS with a conspicuous lack of recommendations for OS X. 

Finally I found two support docs from Apple that shed a lot of light on the problem.  Wi-Fi network roaming with on iOS  Provided the interesting fact that apple supports not even one of the roaming assistance standards that have been released since 2008 while all were supported on iOS. macOS wireless roaming for enterprise customers Which describes how roaming works in OS X including trigger signal levels and preference order and restates that OS X has no support for aany of the roaming assistance standards.

Next

In the next part of this series I will dissect the observer OS X roaming process and limitations.