In an environment with long DHCP release times, its necessary to send DHCP releases on node shutdown. This configuration is available in NetworkManager but seems not to work.     

 OpenShift Container Platform 4.19.16
   

Always

 1. create a MachineConfig that applies the following NetworkManager config:
# cat /etc/NetworkManager/conf.d/99-send-dhcp-release 
[connection] ipv4.dhcp-send-release = true

2. restart NetworkManager and verify that setting did not apply
# nmcli con show br-ex | grep dhcp-send-release
ipv4.dhcp-send-release:                 -1 (default)
ipv6.dhcp-send-release:                 -1 (default)

3. configure send-release direct via nmcli
# sudo nmcli con modify br-ex ipv4.dhcp-send-release yes
# nmcli con show br-ex | grep dhcp-send-release
ipv4.dhcp-send-release:                 1 (true)
ipv6.dhcp-send-release:                 -1 (default)

1. restart the server and observe that no DHCP release messages got sent 
2. verify that the settings manually applied with nmcli con modify are not present anymore 
# nmcli con show br-ex | grep dhcp-send-release 
ipv4.dhcp-send-release: -1 (default) 
ipv6.dhcp-send-release: -1 (default)      
3. Observe that the physical interface is shutdown before the bridge interface, as shown in the additional info section.

The DHCP release message should be sent

The Network Manager stops the physical interface before the bridge interface. 

Oct 30 12:49:29 node01 systemd[1]: Stopping Network Manager...Oct 30 12:49:29 node01 NetworkManager[1445]: <info>  [1761828569.4891] caught SIGTERM, shutting down normally.Oct 30 12:49:29 node01 NetworkManager[1445]: <info>  [1761828569.4912] device (ens192)[Open vSwitch Port]: detaching ovs interface ens192Oct 30 12:49:29 node01 NetworkManager[1445]: <info>  [1761828569.4931] device (br-ex)[Open vSwitch Bridge]: state change: activated -> deactivating (reason 'unmanaged', managed-type: 'full')Oct 30 12:49:29 node01 NetworkManager[1445]: <warn>  [1761828569.4971] dispatcher: (32) failed (after 0.003 sec): Could not activate remote peer.Oct 30 12:49:29 node01 NetworkManager[1445]: <info>  [1761828569.4973] device (br-ex)[Open vSwitch Bridge]: state change: deactivating -> unmanaged (reason 'unmanaged-quitting', managed-type: 'full')Oct 30 12:49:29 node01 NetworkManager[1445]: <info>  [1761828569.4984] device (ens192)[Open vSwitch Port]: state change: activated -> deactivating (reason 'unmanaged', managed-type: 'full')Oct 30 12:49:29 node01 NetworkManager[1445]: <warn>  [1761828569.5036] dispatcher: (34) failed (after 0.005 sec): Could not activate remote peer.Oct 30 12:49:29 node01 NetworkManager[1445]: <info>  [1761828569.5038] device (ens192)[Open vSwitch Port]: state change: deactivating -> unmanaged (reason 'unmanaged-quitting', managed-type: 'full')Oct 30 12:49:29 node01 NetworkManager[1445]: <info>  [1761828569.5049] device (br-ex)[Open vSwitch Port]: state change: activated -> deactivating (reason 'unmanaged', managed-type: 'full')Oct 30 12:49:29 node01 NetworkManager[1445]: <warn>  [1761828569.5085] dispatcher: (36) failed (after 0.003 sec): Could not activate remote peer.Oct 30 12:49:29 node01 NetworkManager[1445]: <info>  [1761828569.5087] device (br-ex)[Open vSwitch Port]: state change: deactivating -> unmanaged (reason 'unmanaged-quitting', managed-type: 'full')Oct 30 12:49:29 node01 NetworkManager[1445]: <info>  [1761828569.5088] device (br-ex)[Open vSwitch Port]: detaching ovs interface br-exOct 30 12:49:29 node01 NetworkManager[1445]: <info>  [1761828569.5096] dhcp4 (br-ex)[Open vSwitch Interface]: canceled DHCP transactionOct 30 12:49:29 node01 NetworkManager[1445]: <info>  [1761828569.5096] dhcp4 (br-ex)[Open vSwitch Interface]: activation: beginning transaction (timeout in 45 seconds)Oct 30 12:49:29 node01 NetworkManager[1445]: <info>  [1761828569.5096] dhcp4 (br-ex)[Open vSwitch Interface]: state changed no leaseOct 30 12:49:29 node01 NetworkManager[1445]: <info>  [1761828569.5114] device (br-ex)[Open vSwitch Interface]: state change: activated -> deactivating (reason 'unmanaged', managed-type: 'full')Oct 30 12:49:29 node01 NetworkManager[1445]: <warn>  [1761828569.5142] dispatcher: (38) failed (after 0.002 sec): Could not activate remote peer.Oct 30 12:49:29 node01 NetworkManager[1445]: <info>  [1761828569.5144] manager: NetworkManager state is now CONNECTED_LOCALOct 30 12:49:29 node01 NetworkManager[1445]: <info>  [1761828569.5146] device (br-ex)[Open vSwitch Interface]: state change: deactivating -> unmanaged (reason 'unmanaged-quitting', managed-type: 'full')Oct 30 12:49:29 node01 NetworkManager[1445]: <info>  [1761828569.5266] exiting (success)Oct 30 12:49:29 node01 systemd[1]: NetworkManager.service: Deactivated successfully.Oct 30 12:49:29 node01 systemd[1]: Stopped Network Manager.Oct 30 12:49:29 node01 systemd[1]: NetworkManager.service: Consumed 4min 58.130s CPU time.