Migration Best Practises in a 24/7 environment AP + WLC replacement

[JonathanC1]

Hi Everyone,

We are looking at replacing our old APs and WLC in one of our hospitals which is 24/7. We will are building an SD-Access environment in parallel whereby we will stand up new 9100 series APs and 9800 WLC.

There are many APs! I was wondering if I can clarify the approach that I think we should take when we finally get there as we can't do this all in one go.

(1) Stand up SD-Access components - ISE, DNAC, WLC, switches

(2) Migrate Wired

(3) Test 2 APs for one floor registering with the 9800s and working as expected for configured SSIDs.

(4)  Migrate a floor or an area at a time for the 9800s by replacing APs physically

I'm worried about two things will the SSID being the same be a problem - This is difficult to change. Is there a best practice in doing this (e.g. swapping one out at a time.)  I expect sessions to break between different controllers if people did roam and ideally we would do this 1 at a time in hours as there's thousands.

If it is possible is it better to migrate the old APs to the 9800 first to avoid roaming problems.

Thank you in advanced

JC

[Leo Laohoo]

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@JonathanC1 wrote:
(3) Test 2 APs for one floor registering with the 9800s and working as expected for configured SSIDs.

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Test the configuration of the 9800 for how long?  We tested ours for 4 months before we migrated 2k APs to our new 9800.  I only needed 4 minutes and 45 seconds worth of outage.  The migration happened on a Thursday work day, started at 12 noon.

[JonathanC1]

Open to testing for a prolonger period around a month at least we think. So you tested a number of APs in an area of the building for several months - would that mean roaming breaks between them and legacy controller APs with the same SSID?

Thank you

JC

[Leo Laohoo]

We have two buildings, about 15 APs each, that are physically separated from the main medical facility.  Those APs verified our configurations until we were ready to cut over the rest of the campus and satellite offices.  And once the users leave these two building they will get disconnected from the WiFi because the next APs were a distance away.

Most important thing to test were wireless VoIP calls using Spectralink, Ascom i62 and Cisco CP-8821.  

Testing with only two APs is not going to have any value.  Hard to test roaming with just two APs.  I would need two dozen APs sprinkled above and below and around corners and behind walls.  Two APs ain't going to cut it.

Start with 17.9.3.  Do not bother with 17.3.X or 17.6.X.

[eglinsky2012 · Accepted solution]

The roaming between controllers will be fine if you have the old WLC and the new WLC in the same mobility group. I'm doing it now between 9800s on 17.9.3 and 8540s on 8.10.183.0. Follow this guide for software compatibility and configuration information:

https://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/8-8/b_c9800_wireless_controller-aireos_ircm_dg.html

As always, test before cutting over.

[JPavonM]

Another Best Practice is to test the final code you will be moving to, plus the configurations, with all possible devices on the venue, specially those that are critical (IoT, M2M, laptops, assets). Set a minimum required firmware/driver/software/operating system for the tests and then ask IT to upgrade everything to those versions before moving production.

I have found many issues with devices that are supposed to work under specific configurations but then they are not.