Router provisioning changes NTP source interface

[Sylvain_Che]

Hello,

I have some routers in my network configured with "ntp source Loopback99". These routers are managed in DNAC via this Lo99 interface. When I provision the routers for the 1st time via DNAC (no specific template applied), DNAC changes the NTP source interface to Loopback0 !

Why DNAC does this?
I cannot find any documentation explaining this.

Note: If I revert the NTP source-interface to its original value (Lo99) via CLI, any subsequent provisioning doesn't change the NTP source interface. Weird...

Sylvain.

[DanielP211]

Hello!

Which version of DNAC do you have? Does the router have loopback0 configured?

BR

[Sylvain_Che]

DNAC 2.3.5.5, and yes routers have a Loopback0 configured.

[Sylvain_Che]

This is actually not strictly related to routers.

In fact, if the network device (router or switch) has a Loopback0 interface configured, during the 1st Provisioning DNAC will push the NTP servers configuration as defined under Design > Network Settings (I'm fine with that), and will change the NTP source interface to be Loopback0.

This is really annoying... The only documentation I found stating such is related to AAA servers settings: Cisco DNA Center User Guide, Release 2.3.5.x - Configure Network Settings [Cisco Catalyst Center] - Cisco.

The source interface used for RADIUS and TACACS servers is determined in the following way:

• If the device has a Loopback0 interface configured, Loopback0 is configured as the source interface.

• Otherwise, the interface that Cisco DNA Center uses as the management IP is configured as the source interface.

I hope the documentation will be updated or the behaviour will change in a future release.

I guess my best option would be to remove the NTP servers from Design > Network Settings, and push the NTP configuration via Templates (at least for switches since routers are not really manageable with templates).

Sylvain.