DNAC and CSSM On-Prem - Smart licensed devices deregistration

[Sylvain_Che]

Hello,

I'm currently configuring the SSM Connection Mode in DNA Center to be "On-Prem-CSSM".

When I save the configuration, I get the following warning pop-up which scares me:

I've got several hundreds of network devices already in my inventory, some of them using licenses with enforcement (HSEC for example).

What will happen exactly if I click Confirm button?

From DNAC Admin Guide 2.2.2, it says: 

Caution

If there are any smart-enabled devices in your Cisco DNA Center inventory that are already registered with Cisco SSM, those devices are deregistered from Cisco SSM. After deregistration, Cisco DNA Center inventory-managed devices go into Evaluation License mode, and network performance might degrade or an outage might occur until these devices are registered again. Therefore, we recommend that you perform this operation during a maintenance window.

But on DNAC Admin Guide 2.3.5 (release I'm currently running):

1. If there are devices that need to be registered again with the changed SSM, the Need to Re-Register Devices dialog box appears. Click OK in the dialog box.

(Already checked DNAC and On-Prem SSM (CSSM) Server Integration - Cisco Community)

Regards,

Sylvain.

[pieterh]

this is my understanding of this mechanism
without on-prem CSSM devices register to Cisco online CSSM using DNA center as a proxy for this service
so when changing mode to on-prem, the current registration needs to be replaced

when the current registration is terminated, but this does not mean the device loses it's license immediately
it tries to verify the current registration for a month, then start logging it is not compliant
in time logging intervals decrease, but the device remains functional.

when the using re-registration button, DNA center creates a token for a single device in the on-prem-CSSM
and uses this to re-register the device

so you've got plenty of time to rebuild the registration on the on-prem CSSM
you may need to transfer licenses from the online account to the on-prem-cssm account
so monitor your licenses and logging for some time