Happy Friday, everyone!
In high density areas of our campus (library, center of campus
food courts, large lecture halls, etc), we often turn off some 2.4Ghz radios to
help avoid co-channel interference issues.
We think we're seeing behavior where client devices in motion attach to an AP
in 2.4, then stubbornly hang on to that frequency (and sometimes AP), even if
they end up in a location with a much stronger 5 Ghz signal from a closer AP.
And of course, with the messy nature of the 2.4 band, they're even more
susceptible to interference using a weak signal from a distant AP.
We do have Cisco's band steering already in play, but we think it might be of
limited benefit in situations like this. Our general advice is for clients to
prefer 5.0GHz when they can. But we think most users are just letting their
devices do what they want, and we really have no control over that.
We're considering converting our main SSIDs to offer 5 GHz only. And then
creating a new SSID that offers 2.4 service (MainSSID2-4, or Legacy2-4, or
something).
Because we believe we have good 5.0GHz coverage, we think this change would be
invisible to most users who have 5 GHz capable devices. Their devices are
already configured to connect to our main SSID, and they would just do so in
5Ghz from then on. They'd see the 2.4 SSID offered if they looked, of course.
Clients that are 2.4 only would see our SSID disappear, and need
reconfiguration/reattachment, accept the cert...all the usual onboarding stuff.
Because of this, we'd only make this change after an extensive communication
period to include our support teams, campus partners, and customers.
Most of our campuses IOT-kinda-stuff (which tend both to be 2.4 and need more
attention/configuration) are already on a separate SSID that we wouldn't be
touching. So nothing would change for them.
Questions:
1. Have other large campuses done this? We have ~400 buildings and
~7,300 access points. We have upwards of 60,000 peak concurrent WiFi
connections, with maybe 14,000 of those in 2.4. We don't know how to tell how
many of those can ONLY do 2.4, and how many are 5Ghz capable, but just aren't
for some reason.
2. How did it work?
3. What were the lessons learned/gotchas, either from a technical or
non-technical/communication perspective?
Other advice?
Best Regards,
James Seddon
Enterprise Network Operations - Voice and Data
Information Technology Services (ITS)
UC San Diego
858-822-4040
[email protected]<mailto:[email protected]>
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